Library guide NG-MEDIUM/NG-LARGE

Owned by Julia DAUMAL (Unlicensed)
Last updated: 11 Oct, 2022 by Kévin Chopier
84 min read

Table of Content

List of figures

CKS chronograms

Simplified PLL block diagram

PLL block diagram and settings

NG-LARGE CKG block diagram

Simplified NG-LARGE PLL block diagram

WFG diagram

WFG chronograms

NX_WFG_L diagram

WFG chronograms

NX_ADD diagram

NX_LUT diagram

NX_DFF diagram

RFB diagram

DSP simplified block diagram

NX_DSP_L simplified block diagram

RAM diagram

NX_RAM organization (No ECC)

Address and data connections (No ECC)

RAM organization (ECC FAST or SLOW)

Address and data connections (ECC FAST or SLOW)

IOB diagram

IOB_I diagram

IOB_O diagram

SERDES data path simplified diagram

SERDES delay lines control block simplified diagram

FLD activation

FLG activation

Writing and reading delay registers

SER_DES IP Core simplified diagram

NX_DES primitive

NX_SER primitive

Introduction

This document aims at giving guidelines on how to use the provided NX components in VHDL source code for NXmap3. Its purpose is to explain how to correctly instantiate the different supported NX components provided by NanoXplore for NXmap3 synthesis and implementation tools.

 

For each NX component, the reader will find a quick introduction and a description of both the generics and ports. He will also find a diagram of the component with an instantiation example in VHDL.

 

 

 

Clocks distribution and management

 

NX_BD

Description

The NX_BD component describes a Buffer Driver circuit that allows the user to direct the routing of a signal to the general routing or low-skew network.

 

Generics

mode

type string

default value “local_lowskew”

If mode is set to “local_lowskew”, the output signal is routed to local low skew network at TILE level.

If mode is set to “global_lowskew”, the output signal is routed to global low skew network of fabric.

 

Ports

Ports

Direction

Type

Description

I

input

std_logic

Input signal

O

output

std_logic

Output signal

Example

This documentation only provides the instantiation of the component.

 

BD_0 : NX_BD port map ( I => CK_GEN , O => CK_LS );

NX_CKS

Description

The NX_CKS component describes a ClocK Switch circuit that allows glitch free clock generation. It can be used to enable/disable the clock to part of the user’s logic – providing that the output signal will be glitch free – and the delay from the main clock to the generated one is un-significant.

See the following figure for a detailed chronogram.

 

The NX_CKS can be used exclusively by instantiation. The current version of NXmap does not yet support inference for this device.

CKS chronograms

 

The blue internal signals are CMD signal sampled on rising edge (SPL1) and then sampled on falling edge (SPL0). SPL0 is the final enable.

Ports

Ports

Direction

Type

Description

CKI

input

std_logic

Input clock

CMD

input

std_logic

Command

CKO

output

std_logic

Output clock

 

Example

This documentation only provides the instantiation of the component.

 

CKS_0 : NX_CKS port map ( CKI => CK , CMD => ENABLE , CKO => CKG );

 

NX_PLL (NG-MEDIUM)

Description

The NX_PLL component describes a Phase Locked Loop circuit available in NG-MEDIUM. The PLL just as the WaveForm Generators (WFG) is part of the ClocK Generator block (also called CKG). There are 4 CKG blocks, on in each corner of the FPGA die.

Each CKG is composed of one PLL and eight WFG.

Simplified PLL block diagram

 

 

PLL inputs:

  • REF: input reference clock. The input reference clock enters in the REF pin.

  • FBK: The feedback can be external (via clock tree connected to the FBK pin) for phase controlled outputs, or internal to the PLL (no phase control or adjustment of the generated clocks with the REF pin).

If REF pin is connected to a PAD, please declare the pad with Turbo mode enabled.

 

PLL outputs:

  • VCO: the output of the VCO

  • D1, D2 and D3 : three outputs generated by frequency division of the VCO output

  • OSC: Internal 200 MHz oscillator output (used for delays calibration on the PLL feedback path, WFG internal delays and input/output delays). OSC output can also be used as auxiliary clock.

  • RDY: status pin. Goes high when the PLL is locked

 

PLL detailed description and settings:

The next figure shows a more detailed view of the PLL, and the attributes used to configure its functionality.

 

The PLL can generate a set of user’s defined clocks which frequencies are based on the REFerence input clock, with multiply and/or divide factors.

The PLL outputs connect directly with the WaveForm Generators (WFG) of the same ClocK Generator (CKG) for clock buffering and added clock generation flexibility.

 

The REFerence clock can be optionally divided by 2. This divider can be used for example to maintain the VCO input frequency in the allowed range (20 to 100 MHz): Assuming that F(ref) = 150 MHz, setting the divider by 2 allows the VCO to see a 75 MHz frequency.

FeedBacK (FBK pin): The feedback can be internal or external.

 

When external, the feedback must be done by using a clock tree (low skew network). The internally generated clocks can be rising edge aligned with the reference clock input pad (highly recommended to optimize the communications with external components like memories, ADCs, DACs). An optional divider by 2 is included in the external feedback path (user’s selected by setting the “vco_fbkdiv” generic to ‘1’)

 

If internal feedback is chosen, the FBK input pin must be left open. The internal feedback path includes three dividers.

 

  • Divider by 2 (cannot be bypassed)

  • User’s programmable integer divider (nDiv – can divide in the range 2 to 31). See fbk_intdiv generic explanations.

  • Additional optional divider by 2 (user’s selected by setting the “vco_fbkdiv” generic to ‘1’). This divider is also included in the external feedback path.

 

A user’s programmable delay chain allows to delay the feedback to the VCO feedback. This feature can be used to fine tune the rising edge alignment of the generated clocks with the REFerence input pad, when external feedback is used – with clock tree. Each delay step is 159 ps. The user can select 0 to 63 steps.

 

  • VCO (PLL core)

    • The VCO generates a frequency in the range 200 MHz to 1200 MHz.

    • There are 3 frequency ranges, 200 MHz to 425 MHz, 400 MHz to 850 MHz and 800 to 1200 MHz.

    • The VCO range is defined by the “vco_range” attribute. NanoXplore recommends to choose preferably the lowest possible range when the VCO frequency value is in the overlap between two ranges.

  • Divided outputs

    • There are 3 additional outputs (D1, D2 and D3). Each output has a programmable divider by powers of 2, in the range 1 to 128 (1, 2, 4, 8, 16, 32, 64 or 128).

 

  • Internal 200 MHz oscillator (precision and stability over PVT around 10%)

    • Can be used as auxiliary clock

    • In addition, this oscillator is used by NXmap to calibrate the programmable delays available in :

      • PLL feedback path

      • WFG (to delay the clocks)

      • IOs input, output and tri-state command paths (complex IO banks only)

Generics

location

 

type string

default value “” (no location constraint)

 

This generic allows to define the NX_PLL location directly in the source code (instead of with the addPLLLocation method)

 

Example : location => “CKG2.PLL1”,

 

vco_range (1)

 

type integer (range 0 to 2)

default value 0

 

This generic configures the VCO frequency range. The value must be in range 0 to 2 according to the following ranges:

 

vco_range

VCO frequency

Unit

Min

Max

0

200

425

MHz

1

400

850

MHz

2

800

1200

MHz

 

 

ref_div_on (2)

 

type bit

default value ‘0’

 

This generic configures whether the input reference frequency is divided by 2 (vco_refdiv = ‘1’) or not (vco_refdiv = ‘0’).

It can be useful to maintain the input reference clock, and the VCO frequencies into their respective ranges.

ref_div_on

Reference frequency range

Unit

Min

Max

‘0’

20

100

MHz

‘1’

40

200

MHz

 

 

ext_fbk_on (3)

 

type bit

default value ‘0’

 

When ‘0’, the internal feedback path is selected. The nDivider whose value is defined by fbk_intdiv and associated pre-divider by 2 are then used.

When ‘1’, the external feedback path is selected. This can be useful to ensure rising edges alignment of the REFerence input clock pad and internal clock trees for fully synchronous behavior with external source and destination components.

 

 

fbk_div_on (4)

 

type bit

default value ‘0

 

This generic configures whether the VCO feedback frequency is divided by 2 (‘1’) or not (‘0’). See also fbk_intdiv to set the global division factor on the internal feedback path.

 

 

fbk_delay_on (5)

 

type bit

default value ‘0’

 

This generic configures whether the delay of the feedback path is active (‘1’) or not (‘0’).

 

 

fbk_delay (6)

 

type integer (range 0 to 63)

default value 0

 

The number of delay taps on the feedback path (internal or external) can be adjusted to meet the required phase on the VCO outputs. When using external feedback, it can be used to compensate the delay on the reference clock input to the REF pin of the PLL via the semi-dedicated clock input pin and associated direct routing.

The delay can be selected or not (see fbk_delay_on). When selected, it can be adjusted from 340 ps (fbk_delay = 0) to 10 400 ps (fbk_delay = 63) by steps of 160 ps.

 

 

fbk_intdiv (7)

 

type integer (range 1 to 15 or 2 to 31)

default value 0

 

This generic allows to define (together with fbk_div_on) the division factor of the VCO frequency on the internal feedback path.

 

fbk_intdiv (nDivider)

fbk_div_on

Division factor on feedback path

0

‘0’

Not allowed

1

‘0’

Not allowed

2

‘0’

4

3

‘0’

6

...

‘0’

...

30

‘0’

60

31

‘0’

62

 

 

 

0

‘1’

Not allowed

1

‘1’

4

2

‘1’

8

3

‘1’

12

...

‘1’

...

14

‘1’

56

15

‘1’

60

16 to 31

‘1’

Not allowed

 

 

clk_outdiv1 (8)

 

type integer (range 0 to 7)

default value 0

 

This generic allows to define the divider value of the D1 output. There are 8 possible values, 1, 2, 4, 8, 16, 32, 64 and 128 (2**clk_outdiv(1))

 

If clk_outdiv(1) = 0 (default value)

D1_output_frequency = Fvco/(2**0) = Fvco

 

If clk_outdiv(1) = 7

D1_output_frequency = Fvco/(2**7) = Fvco/128

 

 

clk_outdiv2 (9)

 

type integer (range 0 to 7)

default value 0

 

This generic allows to define the divider value of the D2 output. There are 8 possible values, 1, 2, 4, 8, 16, 32, 64 and 128 (2**clk_outdiv(2))

 

If clk_outdiv(2) = 0 (default value)

D2_output_frequency = Fvco/(2**0) = Fvco

 

If clk_outdiv(2) = 7

D2_output_frequency = Fvco/(2**7) = Fvco/128

 

 

clk_outdiv3 (10)

 

type integer (range 0 to 7)

default value 0

 

This generic allows to define the divider value of the D3 output. There are 8 possible values, 1, 2, 4, 8, 16, 32, 64 and 128 (2**clk_outdiv(3))

 

If clk_outdiv(3) = 0 (default value)

D3_output_frequency = Fvco/(2**0) = Fvco

 

If clk_outdiv(3) = 7

D3_output_frequency = Fvco/(2**7) = Fvco/128

 

 

Notes about user’s adjustable delays on NG-MEDIUM:

 

The PLL have a user’s selectable and adjustable (no delay or 0 to 63 x 160 ps +/- 5% delay taps) on the feedback path. A similar delay chain is available in each WFGs. Finally the IO banks have input, output and tri-state command 64-tap delay chains.

All the delay chain taps are calibrated with the same procedure and hardware resources.

 

The procedure is transparent to the user.

 

The delays calibration system uses the PLL 200 MHz oscillator output as reference clock to calibrate all delays: feedback path in the PLL itself, WFG delays in same CKG), and IO delays in the two neighboring complex and simple IO banks:

  • CKG1 oscillator calibrates the delays in CKG1 (PLL + WFGs) and IO banks 0, 12 and 11

  • CKG2 oscillator calibrates the delays in CKG2 (PLL + WFGs) and IO banks 1, 2 and 3

  • CKG3 oscillator calibrates the delays in CKG3 (PLL + WFGs) and IO banks 4, 5, 6 and 7

  • CKG4 oscillator calibrates the delays in CKG4 (PLL + WFGs) and IO banks 8, 9 and 10

 

The calibration procedure takes about 10 µs at startup. No status is available on NG-MEDIUM.

 

Ports

Ports

Direction

Type

Description

 

REF

 

 

In

 

std_logic

Reference clock input

Connectivity: semi-dedicated clock inputs, clock trees (low skew network)

Note: If REF pin is connected to a PAD, please declare the pad with Turbo mode enabled.

 

FBK

 

 

In

 

std_logic

External FeedBack input

Connectivity: semi-dedicated clock inputs, clock trees (low skew network)

 

VCO

 

 

Out

 

std_logic

VCO output : Fvco = fbk_intdiv * 2**(fbk_div_on - ref_div_on + 1) * clk_ref_freq

Connectivity: WFG inputs

 

D1…D3

 

 

Out

 

std_logic

Divided clocks. Fvco frequency divided by 1, 2, 4, 8, 16, 32, 64 or 128

Important note: D1, D2 and D3 outputs are reset while PLL RDY is not asserted.

Connectivity: WFG inputs

 

OSC

 

 

Out

 

std_logic

Internal 200 MHz oscilator

Connectivity :WFG inputs, delay calibration system

 

RDY

 

 

Out

 

std_logic

High when PLL is locked

Connectivity: RDY inputs of WFGs, fabric…

 

Instantiation Example

This documentation only provides the instantiation of the component.

 

-- targetFreq = (refFreq * (2 * fbk_intdiv)) / (2^clk_outdiv1)) -- 12.5 MHz = (25 MHz * (2 * 4) / (2^4)) -- 50 MHz = (25 MHz * (2 * 4) / (2^2)) -- -- Please note that (refFreq * (2 * fbk_intdiv)) must be above 200 MHz and below 1200 MHz PLL_0 : NX_PLL generic map ( location => “CKG1.PLL1” , fbk_intdiv => 4 , clk_outdiv1 => 4 -- Divide by 2**4 = 16 , clk_outdiv2 => 2 -- Divide by 2**2 = 4 ) port map ( REF => ck25MHz , FBK => OPEN , VCO => OPEN, , D1 => ck12_5MHz , D2 => ck50MHz , D3 => OPEN , OSC => OPEN , RDY => OPEN );

Simulation

The NX_PLL VHDL simulation model is included in the NxLibrary (NxPackage.vhd). It allows to simulate any one of the possible NX_PLL configurations.

 

 

NX_PLL_L (NG-LARGE)

Description

The NX_PLL_L component describes a Phase Locked Loop circuit available in NG-LARGE The PLL just as the WaveForm Generators (WFG) is part of the ClocK Generator block (also called CKG). There are 4 CKG blocks, on in each corner of the FPGA die.

Each CKG is composed of one PLL and ten WFG.

 

 

The next figure shows a block diagram of the NX_PLL_L and the user’s settings (in yellow).

 

PLL inputs:

  • REF: input reference clock. The input reference clock enters in the REF pin. (20MHz to 50MHz max)

  • FBK: The feedback can be external (via clock tree connected to the FBK pin) for phase controlled outputs, or internal to the PLL (no phase control or adjustment of the generated clocks with the REF pin).

If REF pin is connected to a PAD, please declare the pad with Turbo mode enabled.

 

PLL outputs:

  • VCO: the output of the VCO

  • DIVP1, DIVP2 and DIVP3 : three outputs generated by frequency division (power of 2) of the VCO output

  • DIVO1 and DIVO2 : two additional outputs generated by frequency division (odd ratio) of the VCO output

  • LDFO : This is the output of the internal feedback divider (divides by (fbk_intdiv + 2) * 2 ). Note that LDFO output can be also directed to WFG for clock generation, and the used as external feedback.

 

OSC: 200 MHz output coming from 400MHz internal oscillator (used for delays calibration on the PLL feedback path, WFG internal delays and input/output delays). OSC output can also be used as auxiliary clock.

 

  • PLL_LOCKED: status pin. Goes high when the PLL is locked

  • CAL_LOCKED : this output goes high when the automatic process of delay calibration has completed (PLL and internal delays as well as neighboring IO banks delay)

Generics

 

location

 

type string

default value “”

 

This generic allows to define the NX_PLL_L location directly in the source code (instead of with the nxpython addPLLLocation method).

 

Example : location => “CKG2.PLL1”

 

cfg_use_pll

 

type bit

default value '1'

 

Set to 1 to enable the PLL. When set to 0, the PLL is bypassed with Fvco = Frefo.

 

ref_intdiv

 

type integer (range 0 to 31)

default value 0

 

The REFerence frequency can be divided by factors ranging from 1 to 32 be fore reaching the VCO input. This allows to give more flexibility of the PLL generated output frequency, and increase the PLL input frequency range.

 

ref_intdiv value

Vco input frequency

REF frequency range

0

Fref

20 to 50 MHz

1

Fref / 2

40 to 100 MHz

2

Fref / 3

60 to 150 MHz

3

Fref / 4

80 to 200 MHz

 

 

 

29

Fref / 30

 

30

Fref / 31

 

31

Fref / 32

 

 

 

ref_osc_on

 

type bit

default value ‘0’

 

This generic configures the source of the PLL reference.

 

If ref_osc_on is set to ‘0’, the input reference of the pll is the REF input pin.

If set to ‘1’, the internal oscillator is used as reference of the PLL.

 

 

ext_fbk_on

 

type bit

default value ‘0’

 

When ‘0’, the internal feedback path is selected. The output of the FBK_INTDIV divider is used as feedback source. The VCO output frequency is divided by (fbk_intdiv + 2) * 2

When ‘1’, the external feedback path is selected. This is particularly useful for “zero delay” clock generation.

 

 

fbk_intdiv

 

type Integer range 0 to 31

default value 2

 

fbk_intdiv

Division factor on internal feedback path

0

4

1

6

2

8

3

10

...

...

30

64

31

66

 

fbk_delay_on

 

type bit

default value ‘0’

 

This generic configures whether the delay of the feedback path is active (‘1’) or not (‘0’).

 

 

fbk_delay

 

type integer (range 0 to 63)

default value 0

 

The number of delay taps on the feedback path (internal or external) can be adjusted to meet the required phase on the VCO outputs. When using external feedback, it can be used to compensate the delay on the reference clock input to the REF pin of the PLL via the semi-dedicated clock input pin and associated direct routing.

The delay can be selected or not (see fbk_delay_on). When selected, it can be adjusted from 340 ps (fbk_delay = 0) to 10 400 ps (fbk_delay = 63) by steps of 160 ps.

 

 

clk_outdivp1 : applies to DIVP1

 

type integer (range 0 to 7)

default value 0

 

This generic allows to define the divider value of the DIVP1 output. There are 8 possible values, 1, 2, 4, 8, 16, 32, 64 and 128 (2**clk_outdivp1)

 

If clk_outdivp1 = 0 (default value)

DIVP1_output_frequency = Fvco/(2**0) = Fvco

 

If clk_outdivp1 = 7

DIVP1_output_frequency = Fvco/(2**7) = Fvco / 128

 

 

clk_outdivp2 : applies to DIVP2

 

type integer (range 0 to 7)

default value 0

 

This generic allows to define the divider value of the DIVP2 output. There are 8 possible values, 2, 4, 8, 16, 32, 64, 128 and 256 (2**(clk_outdivp2 + 1))

 

If clk_outdivp2 = 0 (default value)

DIVP2_output_frequency = Fvco/(2**(0 + 1)) = Fvco / 2

 

If clk_outdivp2 = 7

DIVP2_output_frequency = Fvco/(2**(7 + 1)) = Fvco / 256

 

 

clk_outdivp3o2 : applies to DIVP3 and DIVO2 dividers

 

type integer (range 0 to 7)

default value 0

 

This generic allows to define the divider value of both DIVP3 and DIVO2 outputs. There are 8 possible values for each divider :

 

DIVP3 division ratio = 4, 8, 16, 32, 64, 128, 256 and 512 (2**(clk_outdivp3o2 + 2))

If clk_outdivp3 = 0 (default value)

DIVP3_output_frequency = Fvco/(2**(0 + 2)) = Fvco / 4

If clk_outdivp3 = 7

DIV3_output_frequency = Fvco/(2**(7 + 2)) = Fvco / 512

 

DIVO2 division ratio = 5, 7, 9, 11, 13, 15, 17 and 19 ((2 * clk_outdivp3o2) + 5)

If clk_outdivp3o2 = 0 (default value)

DIVO2_output_frequency = Fvco/((2 * 0) + 5) = Fvco / 5

If clk_outdivp3o2 = 7

DIVO2_output_frequency = Fvco/((2 * 7) + 5) = Fvco / 19

 

 

 

clk_outdivo1 : applies to DIVO1

 

type integer (range 0 to 7)

default value 0

 

This generic allows to define the divider value of the DIVO1 output. There are 8 possible values, 3, 5, 7, 9, 11, 13, 15 and 17 ((2*clk_outdivo1) + 3)

 

If clk_outdivo1 = 0 (default value)

DIVO1_output_frequency = Fvco/((2 * 0) + 3) = Fvco / 3

 

If clk_outdivo1 = 7

DIVO1_output_frequency = Fvco/((2 * 7) + 3) = Fvco / 17

 

 

 

Notes about user’s adjustable delays on NG-LARGE:

 

The PLL have a user’s selectable and adjustable delay line (no delay or 0 to 63 x 160 ps +/- 5% delay taps) on the feedback path. A similar delay chain is available in each WFGs. Finally the IO banks have input, output and tri-state command 64-tap delay chains.

All the delay chain taps are calibrated with the same automatic process and hardware resources.

 

The procedure is transparent to the user.

 

The delays calibration system uses the PLL 200 MHz output coming from oscillator as reference clock to calibrate all delays: feedback path in the PLL itself, WFG delays in same CKG), and IO delays in the two neighboring complex and simple IO banks:

 

  • CKG1 oscillator calibrates the delays in CKG1 (PLL + WFGs)

    • Banks 19 to 23 (complex)

  • CKG2 oscillator calibrates the delays in CKG2 (PLL + WFGs)

    • Banks 0 to 5 (simple)

  • CKG3 oscillator calibrates the delays in CKG3 (PLL + WFGs)

    • Banks 6 to 10 (complex)

  • CKG4 oscillator calibrates the delays in CKG4 (PLL + WFGs)

    • Banks 11 to 18 (simple)

 

 

The calibration procedure takes about 10 µs at startup. The “CAL_LOCKED” output goes high when the delay calibration process is complete. Can be used as status bit.

 

Ports

Ports

Direction

Type

Description

 

REF

 

 

In

 

std_logic

Reference clock input

Connectivity: semi-dedicated clock inputs, clock trees (low skew network)

Note: If REF pin is connected to a PAD, please declare the pad with Turbo mode enabled.

 

FBK

 

 

In

 

std_logic

External FeedBack input

Connectivity: semi-dedicated clock inputs, clock trees (low skew network)

 

R

 

 

In

 

std_logic

Active high Reset input. Must be activated when REF input frequency changes to force a re-locking process of the PLL

 

VCO

 

 

Out

 

std_logic

 

VCO output:

- Internal feedback: Fvco = 2 * (fbk_intdiv + 2) * clk_ref_freq / (ref_intdiv + 1)

- External feedback: Fvco = (pattern_end + 1) / n_sim_pat * clk_ref_freq / (ref_intdiv + 1)

Where n_sim_pat is the number of similar patterns sequence found in pattern_end+1 MSB bits of pattern.

 

REFO

 

Out

 

std_logic

Output of the REFerence divider. The division factor is set by the generic “ref_intdiv”

 

 

LDFO

 

Out

 

std_logic

Output of the FBK_INTDIV divider. The division factor is set by the generic ‘fbk_intdiv”

 

 

DIVP1

 

Out

 

std_logic

This output delivers a divided VCO frequency (by a power of 2). The division factor is set by the generic “clk_divoutp1”

 

 

DIVP2

 

Out

 

std_logic

This output delivers a divided VCO frequency (by a power of 2). The division factor is set by the generic “clk_divoutp2”

 

 

DIVP3

 

Out

 

std_logic

This output delivers a divided VCO frequency (by a power of 2). The division factor is set by the generic “clk_divoutp3o2”

 

 

DIVO1

 

Out

 

std_logic

This output delivers a divided VCO frequency (by an odd factor). The division factor is set by the generic “clk_divouto1”

 

 

DIVO2

 

Out

 

std_logic

This output delivers a divided VCO frequency (by an odd factor). The division factor is set by the generic “clk_divoutp3o2”

 

 

OSC

 

 

Out

 

std_logic

200 MHz coming from 400MHz internal oscilator

Connectivity :WFG inputs, delay calibration engine

 

PLL_LOCKED

 

 

Out

 

std_logic

High when PLL is locked

Connectivity: RDY inputs of WFGs, fabric…

 

CAL_LOCKED

 

 

Out

 

std_logic

High when the automatic calibration procedure of the current FPGA quarte area is complete

Connectivity: fabric

 

 

Instantiation Example

This documentation only provides the instantiation of the component.

 

Simulation

The NX_PLL VHDL simulation model is included in the NxLibrary (NxPackage.vhd). It allows to simulate any one of the possible NX_PLL configurations.

 

 

 

NX_WFG (NG-MEDIUM)

Description

The NX_WFG component is used to access the low skew lines and clock trees. Among the main WFG features:

  • User’s selectable clock inversion

  • Programmable delay line (0 to 64 taps)

  • Waveform generation by using a 2 to 16-tap user’s defined pattern

  • Includes synchronization with other WFG using pattern, in the same ClocK Generator

 

Generics

delay

type integer

default value 0

This generic represents the delay line tap count. The value must be in range [0:63] for a tap count in range [1:64].

 

delay_on

type bit

default value ‘0’

This generic configures whether the generated clock is delayed (‘1’) or not (‘0’).

 

pattern_end

type integer

default value 0

This generic configures the last useful index of the sampling pattern. The value must be in range [0:15]. When set to 1 only the 2 first bits of the pattern are used to sample the input clock.

 

mode

type bit

default value ‘0’

This generic configures whether the generated clock is using the WFG pattern (‘1’) or not (‘0’).

 

pattern

type bit_vector(0 to 15)

default value b”0000000000000000”

This generic configures the sampling pattern. The pattern is temporal which means the first bit considered if left most one.

For example, with a pattern set to b”1000000000000000” and a pattern_end set to 2, only the first 3 bits of the pattern are considered (“100”) and the input and output clocks chronograms are:

 

wfg_edge

type bit

default value ‘0’

This generic configures whether the input clock is inverted (‘1’) or not (‘0’). When sampling the input clock, this generic configures whether the sampling is done on rising edge (‘0’) or falling edge (‘1’).

 

Ports

Ports

Direction

Type

Description

SI

input

std_logic

Synchronization input (connected to the synchronization output of the master WFG)

ZI

input

std_logic

Input clock (connected to PLL VCO or D1, D2 or D3 output)

RDY

input

std_logic

Usually connected to the PLL RDY pin. Must be left unconnected for the WFG that generates the clock feedback for the PLL using external feedback.

RDY input is an active low reset. When low, it disables the WFG behavior. When high or open, the WFG works as specified.

SO

output

std_logic

Synchronization output (Master WFG SO output is connected to all slave WFGs SI inputs)

ZO

output

std_logic

Generated clock (connected to clock tree)

Synchronizing WFG together can be useful if output clocks must be synchronous. It is made by getting the same source clock for Master and Slave WFG and connecting SO from Master WFG to Si of Slave WFG.

Example

This documentation only provides the instantiation of the component.

 

 

 

Simulation

The NX_WFG VHDL simulation model is included in the NxLibrary (NxPackage.vhd). It allows to simulate any one of the possible NX_WFG configurations.

 

NX_WFG_L (NG-LARGE)

Description

The NX_WFG_L component is used to access the low skew lines and clock trees on NG-LARGE. The NX_WFG_L is very similar to the NX_WFG of NG-MEDIUM. The difference is that the NX_WFG_L have an additional active high Reset input.

Among the main WFG features:

  • User’s selectable clock inversion

  • Programmable delay line (0 to 64 taps)

  • Waveform generation by using a 2 to 16-tap user’s defined pattern

  • Includes synchronization with other WFG using pattern, in the same ClocK Generator

Generics

 

location

 

type string

default value “” (no location constraint)

 

This generic allows to define the NX_WFG_L location directly in the source code (with the addWFGLocation method)

 

Example : location => “CKG2.WFG_C2”,

 

delay

type integer

default value 0

This generic represents the delay line tap count. The value must be in range [0:63] for a tap count in range [1:64].

 

delay_on

type bit

default value ‘0’

This generic configures whether the generated clock is delayed (‘1’) or not (‘0’).

 

pattern_end

type integer

default value 0

This generic configures the last useful index of the sampling pattern. The value must be in range [0:15]. When set to 1 only the 2 first bits of the pattern are used to sample the input clock.

 

mode

type bit

default value ‘0’

This generic configures whether the generated clock is using the WFG pattern (‘1’) or not (‘0’).

 

pattern

type bit_vector(0 to 15)

default value b”0000000000000000”

This generic configures the sampling pattern. The pattern is temporal which means the first bit considered if left most one.

For example, with a pattern set to b”1000000000000000” and a pattern_end set to 2, only the first 3 bits of the pattern are considered (“100”) and the input and output clocks chronograms are:

 

wfg_edge

type bit

default value ‘0’

This generic configures whether the input clock is inverted (‘1’) or not (‘0’). When sampling the input clock, this generic configures whether the sampling is done on rising edge (‘0’) or falling edge (‘1’).

 

Ports

Ports

Direction

Type

Description

SI

input

std_logic

Synchronization input (connected to the synchronization output of the master WFG)

ZI

input

std_logic

Input clock (connected to PLL VCO or D1, D2 or D3 output)

RDY

input

std_logic

Usually connected to the PLL RDY pin. Must be left unconnected for the WFG that generates the clock feedback for the PLL using external feedback.

RDY input is an active low reset. When low, it disables the WFG behavior. When high or open, the WFG works as specified.

R

Input

std_logic

Active high Reset. Can be fed by the LOCKED output of the NX_PLL_L.

SO

output

std_logic

Synchronization output (Master WFG SO output is connected to all slave WFGs SI inputs)

ZO

output

std_logic

Generated clock (connected to clock tree)

 

Example

This documentation only provides the instantiation of the component.

 

imulation

The NX_WFG_L VHDL simulation model is included in the NxLibrary (NxPackage.vhd). It allows to simulate any one of the possible NX_WFG_L configurations.

 

 

 

 

Core logic

NX_CY (!)

Description

The NX_ADD component describes a 4-bit adder and carry look ahead circuit. It’s available on the FEs having arithmetic logic capabilities.

The NX_ADD is composed of 4 stages numbered from 1 to 4 where 1 represents the LSB.

 

Generics

add_carry

type integer range 0 to 2

default value 0

This generic represents the way the CI (carry in) port is connected: 0 is for low, 1 for high and 2 for propagate which means it is connected to the previous NX_CY CO (carry out) port.

 

Ports

Ports

Direction

Type

Description

A[1:4]

input

std_logic

A input of each stage

BI[1:4]

input

std_logic

B input of each stage

CI

input

std_logic

Carry input

CO

output

std_logic

Carry output

S[1:4]

output

std_logic

Output of each stage

Example

This documentation only provides the instantiation of the component..

 

 

NX_LUT

Description

The NX_LUT component describes a 4-input LUT as part of a functional element (FE) as shown in the following diagram:

 

Generics

lut_table

type bit_vector(15 downto 0)

default value b“0000000000000000”

This generic represents the truth table of the associated LUT. The string representing the truth table is MSB ordered (“b(15), b(14),...b(1), b(0)”) and b(15) to b(0) are defined as in the following table:

 

I4

1

1

1

1

1

1

1

1

0

0

0

0

0

0

0

0

I3

1

1

1

1

0

0

0

0

1

1

1

1

0

0

0

0

I2

1

1

0

0

1

1

0

0

1

1

0

0

1

1

0

0

I1

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

O

b(15)

b(14)

b(13)

b(12)

b(11)

b(10)

b(9)

b(8)

b(7)

b(6)

b(5)

b(4)

b(3)

b(2)

b(1)

b(0)

 

Lut_table examples for common 4-input functions:

  • I4 and I3 and I2 and I1 => lut_table = b“1000000000000000” (or x”8000”)

  • I4 or I3 or I2 or I1 => lut_table = b“1111111111111110” (or x”FFFE”)

  • (I4 and I3) xor (I2 and I1) => lut_table = x”0111 1000 1000 1000” (or x”7888”)

 

Ports

Ports

Direction

Type

Description

I[1:4]

input

std_logic

LUT inputs

O

output

std_logic

Output

 

Example

This documentation only provides the instantiation of the component.

NX_DFF

Description

The NX_DFF component describes a DFF of the functional elements as shown in the following diagram:

 

Generics

dff_ctxt

type std_logic

default value ‘U’

This generic represents the initial value of the associated DFF. The initial value is set by bitstream. The available values are: ‘U’ for undefined (no value set in bitstream), ‘0’ for low and ‘1’ for high.

 

dff_edge

type bit

default value ‘0’

This generic represents the front polarity of the clock of the associated DFF. ‘0’ is for rising edge and ‘1’ for falling edge.

 

dff_init

type bit

default value ‘0’

This generic represents whether the DFF considers the R (reset) input. ‘0’ is for ignore and ‘1’ for using connected net.

 

dff_load

type bit

default value ‘0’

This generic represents whether the DFF considers the L (load) input. ‘0’ is for ignore and ‘1’ for using connected net.

 

dff_sync

type bit

default value ‘0’

This generic represents whether the DFF reset is synchronous or asynchronous. ‘0’ is for asynchronous and ‘1’ for synchronous.

 

dff_type
type integer
default value 0
This generic represents whether the reset must initialize the DFF to 0 or 1. dff_type is set to ‘0’ for reset initializing the DFF to 0, dff_type is set to ‘1’ for reset initializing the DFF to 1. dff_type can also be set to 2 to configure set/reset on signal.

Ports

Ports

Direction

Type

Description

I

input

std_logic

Input

CK

input

std_logic

Clock

L

input

std_logic

Load

R

input

std_logic

Reset

O

output

std_logic

Output

 

Example

This documentation only provides the instantiation of the component.

 

NX_RFB

Description

The NX_RFB component describes a Register File Block circuit that is a Simple Dual Port memory of 64 words of 16-bit (one is port dedicated to write, the second port is dedicated to read). The circuit includes Error Code Correction (EDAC).

The Register_File block is made of:

  • One 64 x 16-bit Simple Dual Port RAM with user’s transparent EDAC

  • Maximum 32 + 18 FE from the same tile stripe used to route inputs and outputs.

 

Associated FE usage :

 

If the Register_File is not used, all the 32 FE are free to be used to implement user’s logic

 

  • If the Register_File is used, up to 30 inputs will reach the 64 x 16 RAM array by crossing FE, and 2 additional LUTs will be used for internal configuration purpose

    • 1 LUT for Read_Enable (with potential 4-input decoder)

    • 1 LUT for Write_Enable (with potential 4-input decoder)

    • 6 LUTs for Write_Address

    • 6 LUTs for Read_Address

    • 16 LUTs for Data_In

    • 2 additional LUTs for RF internal configuration

 

Using the whole RAM array (64 x 16) requires using 32 FE of the same tile section.

The FE can implement optional customer logic, for example

  • Implement simple decoding functions for Write_Enable or Read_Enable

  • Address/Data multiplexers to implement time multiplexed two write ports and/or two read ports (not yet supported by NXmap)

(see NXmap related notes for more details)

 

  • If the Register_File is used, up to 18 outputs will come from the 64 x 16 RAM array by crossing FE, those registers can be implemented with FE Flip-Flops of the same tile section (16 for Data_out + 2 for ERR and COR outputs)

  • If the Register_File is partially used (for example as 64 x 8 SDP RAM), the remaining 8 FEs will stay free to implement other unrelated logic functions)

 

Generics

mem_ctxt (1)

type string

default value “”

This generic represents the initial value of the RFB. The initial value is set by bitstream. The string contains a list of all complete bit words separated by coma.

When a word size is less than 16 bits or when number of words is less than 64, an error occurs.

When a word size exceeds 16 bits or when the number of words exceeds 64, an error occurs.

 

ren_table (2)

type bit_vector(15 downto 0)

default value b“0000000000000000”

This generic represents the truth table of the LUT associated to RE input.

 

 

rck_edge (3)

type bit

default value ‘0’

This generic represents the front polarity of the RCK clock. ‘0’ is for rising edge and ‘1’ for falling edge.

 

wen_table (4)

type bit_vector(15 downto 0)

default value b“0000000000000000”

This generic represents the truth table of the LUT associated to WE input.

 

wck_edge (3)

type bit

default value ‘0’

This generic represents the front polarity of the WCK clock. ‘0’ is for rising edge and ‘1’ for falling edge.

 

Ports

Ports

Direction

Type

Description

RCK

input

std_logic

Read clock

WCK

input

std_logic

Write clock

I[1:16]

input

std_logic

Data input

COR

output

std_logic

Correction output flag

ERR

output

std_logic

Error output

O1 to O16

output

std_logic

Data output

RA1 to RA6

input

std_logic

Read address

RE1 to RE4

input

std_logic

Read enable

WA1 to WA6

input

std_logic

Write address

WE1 to WE4

input

std_logic

Write enable

 

Instantiation Example

This documentation only provides the instantiation of the component.

 

NX_DSP (NG-MEDIUM)

Description

The NX_DSP component describes a Digital Signal Processor circuit that allows implementation of arithmetic computations such as multiply, add/subtract.

 

Generics

std_mode

type string

default value “”

This generic represents the predefined operating mode of the DSP. When empty the operating mode is defined by the 4 raw_config generics.

The available predefined modes are:

  • “ADD_36” → 36 bits addition

  • “SUB_36” → 36 bits subtraction

  • “SMUL_18” → 18 bits signed multiplication

  • “UMUL_18” → 18 bits unsigned multiplication

  • “SMUL_EXT” → extension for 24 bits signed multiplication

  • “UMUL_EXT” → extension for 24 bits unsigned multiplication

 

When using one of these predefined modes, the 4 raw_config generics are defined as follow:

  • raw_config0

    • ADD_36 b”00000000000010000000”

    • SUB_36 b”00000000000010000000”

    • SMUL_18 b”00000000001000000001”

    • UMUL_18 b”00000000001000000000”

    • SMUL_EXT b”00000000000001100001”

    • UMUL_EXT b”00000000000001100000”

  • raw_config1

    • All modes b“0000000000000000000000”

  • raw_config2

    • All modes b“0000000000000”

  • raw_config3

    • ADD_36 b“0000001”

    • SUB_36 b“0001011 ”

    • SMUL_18 b“0100000”

    • UMUL_18 b“0100000”

    • SMUL_EXT b”0000000”

    • UMUL_EXT b”0000000”



raw_config0

type bit_vector(19 downto 0)

default value b“00000000000000000000”

This generic configures the following fields:

Name

Index

Description

CO_SEL

19

Carry out MUX for CO and CCO outputs

‘0’ : Select CO37

‘1’ : Select CO49

ALU_DYNAMIC_OP

18

ALU Dynamic Operation

‘0’: use raw_config3 as ALU operation

‘1’: use D1…D6 as ALU operation

SATURATION_RANK

17:12

MSB position for saturation and overflow

Signed : “100000” for range -2**31 to (2**31)-1

Unsigned : “100000” for range 0 to (2**32)-1

Max value = “110111” (55)

ENABLE_SATURATION

11

‘0’: disable, ‘1’: enable

Z_FEEDBACK_SHL12

10

Shift of the Z output for feedback

‘0’ : No shift

‘1’ : 12-bit left shift

 

MUX_Z

9

Selection for Z output

‘0’ : ALU

‘1’ : PR_Y

MUX_CI

8

Carry in MUX

‘0’ : CI input

‘1’ : CCI cascade input

MUX_Y

7

Y operand MUX

‘0’ : MULT

‘1’ : Concat (B, A)

MUX_X

6:5

X operand MUX

“00” : C (sign extended to 56-bit)

“01” : CZI

“11” : CZI(43:0] & C(11:0]

“10” : Z (12-bit left shifted or not)

 

 

 

MUX_P

4

Pre-adder/ B MUX (to multiplier)

‘0’ : B (sign extended)

‘1’ : Pre-adder

MUX_B

3

B input MUX

‘0’ : Select B input port

‘1’ : Select CBI input

MUX_A

2

A input MUX.

‘0’ : Select A input port

‘1’ : Select CAI input

PRE_ADDER_OP

1

Pre-adder operation

‘0’ : add (performs B+D)

‘1’ : subtract (performs B-D)

SIGNED_MODE

0

‘0’ : unsigned, ‘1’: signed



raw_config1

type bit_vector(21 downto 0)

default value b“0000000000000000000000”

This generic configures the following fields:

Name

Index

Description

RESERVED

21:19

“000”

PR_OV_MUX

18

ALU overflow pipe register

‘0’ : no pipeline

‘1’ : pipeline

PR_CO_MUX

17

Carry out pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_Z_MUX

16

Z output pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_ALU_MUX

15

ALU out pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_MUL_MUX

14

Multiplier out pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_Y_MUX

13

Y operand pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_X_MUX

12

X operand pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_P_MUX

11

Pre-adder pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_CI_MUX

10

Carry in pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_D_MUX

9

D input pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_C_MUX

8

C input pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_B_CAS_MUX

7:6

Cascaded B input pipe depth

B input pipe depth

Cascaded A input pipe depth

A input pipe depth

“00” : no pipeline

“01” : 1 level pipeline register

“10” : 2 levels pipeline

“11” : 3 levels pipeline

PR_B_MUX

5:4

PR_A_CAS_MUX

3:2

PR_A_MUX

1:0



raw_config2

type bit_vector(12 downto 0)

default value b“0000000000000”

This generic configures the following fields:

Name

Index

Description

PR_OV_RST

12

ALU overflow pipe reset (‘0’ : disable, ‘1’ : enable)

PR_CYO_RST

11

Carry out pipe reset (‘0’ : disable, ‘1’ : enable)

PR_Z_RST

10

Z output pipe reset (‘0’ : disable, ‘1’ : enable)

PR_ALU_RST

9

ALU out pipe reset (‘0’ : disable, ‘1’ : enable)

PR_MUL_RST

8

Multiplier out pipe reset (‘0’ : disable, ‘1’ : enable)

PR_Y_RST

7

Y operand pipe reset (‘0’ : disable, ‘1’ : enable)

PR_X_RST

6

X operand pipe reset (‘0’ : disable, ‘1’ : enable)

PR_P_RST

5

Pre-adder pipe reset (‘0’ : disable, ‘1’ : enable)

PR_CYI_RST

4

Carry in pipe reset (‘0’ : disable, ‘1’ : enable)

PR_D_RST

3

D input pipe reset (‘0’ : disable, ‘1’ : enable)

PR_C_RST

2

C input pipe reset (‘0’ : disable, ‘1’ : enable)

PR_B_RST

1

B input pipe reset (‘0’ : disable, ‘1’ : enable)

PR_A_RST

0

A input pipe reset (‘0’ : disable, ‘1’ : enable)

raw_config3

type bit_vector(6 downto 0)

default value b“0000000”

This generic configures the following fields:

Name

Index

Description

ALU_MUX

6

Swap ALU operand (‘0’ : no swap, ‘1’ : swap)

ALU_OP

5:0

ALU operation (16 valid values over 64 possible combinations)

ALU operation must be set based on the following table:

Operation

Opcode

Equation

Operation

Opcode

Equation

Arithmetic operation

ADD

b”000000”

Z = Y + X

ADDC

b”000001”

 

Z = Y + X + CI

SUB

b”001010”

Z = Y – X

SUBC

b”001011”

Z = Y – X – CI

INCY

b”000101”

Z = Y + CI

DECY

b”000111”

Z = Y – CI

Logic operation

Y

b”100000”

Z = Y

notY

b”110000”

Z = ~Y

AND

b”100001”

Z = Y & X

ANDnotX

b”101001”

Z = Y & ~X

NAND

b”110001”

Z = ~(Y & X)

OR

b”100010”

Z = Y | X

ORnotX

b”101010”

Z = Y | ~X

NOR

b”110010”

Z = ~(Y | X)

XOR

b”100011”

Z = Y ^ X

XNOR

b”110011”

Z = ~(Y ^ X)

INVALID OP

48 other possible values

Z = XXXXXXXXXXXXXX

 

Ports

Ports

Direction

Type

Description

A1 to A24

input

std_logic

24-bit A input

B1 to B18

input

std_logic

18-bit B input

C1 to C36

input

std_logic

36-bit C input

CAI1 to CAI18

input

std_logic

18-bit Cascaded A input

CAO1 to CAO18

output

std_logic

18-bit Cascaded A output

CBI1to CBI18

input

std_logic

18-bit Cascaded B input

CBO1 to CBO18

output

std_logic

18-bit Cascaded B output

CCI

input

std_logic

Cascaded Carry input

CCO

output

std_logic

Cascaded Carry output

CI

input

std_logic

Carry input

CK

input

std_logic

Clock (works on rising edges)

CO

output

std_logic

Carry output

CO37

output

std_logic

Carry output bit 37

CO49

output

std_logic

Carry output bit 49

CZI1 to CZI56

input

std_logic

56-bit Cascaded Z input

CZO1 to CZO56

output

std_logic

56-bit Cascaded Z output

D1 to D18

input

std_logic

18-bit D input

OVF

output

std_logic

Overflow output flag

R

input

std_logic

Reset for pipeline registers except Z output register (active high)

RZ

input

std_logic

Reset for Z output register only(active high)

WE

input

std_logic

Write enable:

‘0’: all DSP internal registers are frozen, ‘1’: normal operation

Z1 to Z56

output

std_logic

56-bit Z output

Instantiation Example

This documentation only provides the instantiation of the component.

 

 

Simulation

The NX_DSP VHDL simulation model is included in the NxLibrary (NxPackage). It allows to simulate any one of the possible NX_DSP configurations.

 

NX_DSP_SPLIT

The NX_DSP_SPLIT is an alternate primitive for using DSP blocks. It can be instantiated as many times as required in your design.

For user’s convenience, the generics are split, and can be modified separately. The input and output busses are grouped.

The following is the declaration of the component NX_DSP_SPLIT_GENERICS, included in the NxPackage.vhd.

 

 

NX_DSP_L (NG-LARGE)

Description

The NX_DSP component describes a Digital Signal Processor circuit that allows implementation of arithmetic computations such as multiply, add/subtract.

The NX_DSP_L is very similar to the NX_DSP available on NG-MEDIUM, with the following two differences :

  • CAO/CAI chain is 24-bit wide instead of 18-bit on NG-MEDIUM

  • CO57 output instead of CO49 on NG-MEDIUM

 

Generics

std_mode

type string

default value “”

This generic represents the predefined operating mode of the DSP. When empty the operating mode is defined by the 4 raw_config generics.

The available predefined modes are:

  • “ADD_36” → 36 bits addition

  • “SUB_36” → 36 bits subtraction

  • “SMUL_18” → 18 bits signed multiplication

  • “UMUL_18” → 18 bits unsigned multiplication

  • “SMUL_EXT” → extension for 24 bits signed multiplication

  • “UMUL_EXT” → extension for 24 bits unsigned multiplication

 

When using one of these predefined modes, the 4 raw_config generics are defined as follow:

  • raw_config0

    • ADD_36 b”00000000000010000000”

    • SUB_36 b”00000000000010000000”

    • SMUL_18 b”00000000001000000001”

    • UMUL_18 b”00000000001000000000”

    • SMUL_EXT b”00000000000001100001”

    • UMUL_EXT b”00000000000001100000”

  • raw_config1

    • All modes b“0000000000000000000000”

  • raw_config2

    • All modes b“0000000000000”

  • raw_config3

    • ADD_36 b“0000001”

    • SUB_36 b“0001011 ”

    • SMUL_18 b“0100000”

    • UMUL_18 b“0100000”

    • SMUL_EXT b”0000000”

    • UMUL_EXT b”0000000”



raw_config0

type bit_vector(19 downto 0)

default value b“00000000000000000000”

This generic configures the following fields:

Name

Index

Description

CO_SEL

19

Carry out MUX for CO and CCO outputs

‘0’ : Select CO37

‘1’ : Select CO49

ALU_DYNAMIC_OP

18

ALU Dynamic Operation

‘0’: use raw_config3 as ALU operation

‘1’: use D1…D6 as ALU operation

SATURATION_RANK

17:12

MSB position for saturation and overflow

Signed : “100000” for range -2**31 to (2**31)-1

Unsigned : “100000” for range 0 to (2**32)-1

Max value = “110111” (55)

ENABLE_SATURATION

11

‘0’: disable, ‘1’: enable

Z_FEEDBACK_SHL12

10

Shift of the Z output for feedback

‘0’ : No shift

‘1’ : 12-bit left shift

 

MUX_Z

9

Selection for Z output

‘0’ : ALU

‘1’ : PR_Y

MUX_CI

8

Carry in MUX

‘0’ : CI input

‘1’ : CCI cascade input

MUX_Y

7

Y operand MUX

‘0’ : MULT

‘1’ : Concat (B, A)

MUX_X

6:5

X operand MUX

“00” : C (sign extended to 56-bit)

“01” : CZI

“11” : CZI(43:0] & C(11:0]

“10” : Z (12-bit left shifted or not)

 

 

 

MUX_P

4

Pre-adder/ B MUX (to multiplier)

‘0’ : B (sign extended)

‘1’ : Pre-adder

MUX_B

3

B input MUX

‘0’ : Select B input port

‘1’ : Select CBI input

MUX_A

2

A input MUX.

‘0’ : Select A input port

‘1’ : Select CAI input

PRE_ADDER_OP

1

Pre-adder operation

‘0’ : add (performs B + D)

‘1’ : subtract (performs B - D)

SIGNED_MODE

0

‘0’ : unsigned, ‘1’: signed



raw_config1

type bit_vector(21 downto 0)

default value b“0000000000000000000000”

This generic configures the following fields:

Name

Index

Description

RESERVED

21:19

“000”

PR_OV_MUX

18

ALU overflow pipe register

‘0’ : no pipeline

‘1’ : pipeline

PR_CO_MUX

17

Carry out pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_Z_MUX

16

Z output pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_ALU_MUX

15

ALU out pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_MUL_MUX

14

Multiplier out pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_Y_MUX

13

Y operand pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_X_MUX

12

X operand pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_P_MUX

11

Pre-adder pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_CI_MUX

10

Carry in pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_D_MUX

9

D input pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_C_MUX

8

C input pipe depth

‘0’ : no pipeline

‘1’ : pipeline

PR_B_CAS_MUX

7:6

Cascaded B input pipe depth

B input pipe depth

Cascaded A input pipe depth

A input pipe depth

“00” : no pipeline

“01” : 1 level pipeline register

“10” : 2 levels pipeline

“11” : 3 levels pipeline

PR_B_MUX

5:4

PR_A_CAS_MUX

3:2

PR_A_MUX

1:0



raw_config2

type bit_vector(12 downto 0)

default value b“0000000000000”

This generic configures the following fields:

Name

Index

Description

PR_OV_RST

12

ALU overflow pipe reset (‘0’ : disable, ‘1’ : enable)

PR_CYO_RST

11

Carry out pipe reset (‘0’ : disable, ‘1’ : enable)

PR_Z_RST

10

Z output pipe reset (‘0’ : disable, ‘1’ : enable)

PR_ALU_RST

9

ALU out pipe reset (‘0’ : disable, ‘1’ : enable)

PR_MUL_RST

8

Multiplier out pipe reset (‘0’ : disable, ‘1’ : enable)

PR_Y_RST

7

Y operand pipe reset (‘0’ : disable, ‘1’ : enable)

PR_X_RST

6

X operand pipe reset (‘0’ : disable, ‘1’ : enable)

PR_P_RST

5

Pre-adder pipe reset (‘0’ : disable, ‘1’ : enable)

PR_CYI_RST

4

Carry in pipe reset (‘0’ : disable, ‘1’ : enable)

PR_D_RST

3

D input pipe reset (‘0’ : disable, ‘1’ : enable)

PR_C_RST

2

C input pipe reset (‘0’ : disable, ‘1’ : enable)

PR_B_RST

1

B input pipe reset (‘0’ : disable, ‘1’ : enable)

PR_A_RST

0

A input pipe reset (‘0’ : disable, ‘1’ : enable)

 

raw_config3

type bit_vector(6 downto 0)

default value b“0000000”

This generic configures the following fields:

Name

Index

Description

ALU_MUX

6

Swap ALU operand (‘0’ : no swap, ‘1’ : swap)

ALU_OP

5:0

ALU operation (16 valid values over 64 possible combinations)

ALU operation must be set based on the following table:

Operation

Opcode

Equation

Operation

Opcode

Equation

Arithmetic operation

ADD

b”000000”

Z = Y+ X

ADDC

b”000001”

 

Z = Y + X + CI

SUB

b”001010”

Z = Y – X

SUBC

b”001011”

Z = Y – X – CI

INCY

b”000101”

Z = Y + CI

DECY

b”000111”

Z = Y – CI

Logic operation

Y

b”100000”

Z = Y

NotY

b”110000”

Z = ~Y

AND

b”100001”

Z = Y & X

ANDnotX

b”101001”

Z = Y & ~X

NAND

b”110001”

Z = ~(Y & X)

OR

b”100010”

Z = Y | X

ORnotX

b”101010”

Z = Y | ~X

NOR

b”110010”

Z = ~(Y | X)

XOR

b”100011”

Z = Y ^ X

XNOR

b”110011”

Z = ~(Y ^ X)

INVALID OP

48 other possible values

Z = XXXXXXXXXXXXXX

 

Ports

Ports

Direction

Type

Description

A1 to A24

input

std_logic

24-bit A input

B1 to B18

input

std_logic

18-bit B input

C1 to C36

input

std_logic

36-bit C input

CAI1 to CAI23

input

std_logic

24-bit Cascaded A input

CAO1 to CAO24

output

std_logic

24-bit Cascaded A output

CBI1to CBI18

input

std_logic

18-bit Cascaded B input

CBO1 to CBO18

output

std_logic

18-bit Cascaded B output

CCI

input

std_logic

Cascaded Carry input

CCO

output

std_logic

Cascaded Carry output

CI

input

std_logic

Carry input

CK

input

std_logic

Clock (works on rising edges)

CO

output

std_logic

Carry output

CO37

output

std_logic

Carry output bit 37

CO57

output

std_logic

Carry output bit 57

CZI1 to CZI56

input

std_logic

56-bit Cascaded Z input

CZO1 to CZO56

output

std_logic

56-bit Cascaded Z output

D1 to D18

input

std_logic

18-bit D input

OVF

output

std_logic

Overflow output flag

R

input

std_logic

Reset for pipeline registers except Z output register (active high)

RZ

input

std_logic

Reset for Z output register only(active high)

WE

input

std_logic

Write enable:

‘0’: all DSP internal registers are frozen, ‘1’: normal operation

Z1 to Z56

output

std_logic

56-bit Z output

 

Instantiation Example

This documentation only provides the instantiation of the component.

 

 

Simulation

The NX_DSP_L VHDL simulation model is included in the NxLibrary (NxPackage). It allows to simulate any one of the possible NX_DSP_L configurations.

 

 

NX_DSP_L_SPLIT

The NX_DSP_L_SPLIT is an alternate primitive for using DSP blocks. It can be instantiated as many times as required in your design.

For user’s convenience, the generics are split, and can be modified separately. The input and output busses are grouped.

The following is the declaration of the component NX_DSP_L_SPLIT, included in the NxPackage.vhd.

 

 

 

NX_ECC

Description

The NX_ECC component describes an Error Code Correction circuit that can be used with memory declaration to add error correction support.

The NX_ECC can be instantiated with inferred memory blocks. The user must connect the LSB of the NX_RAM output data to the CHK input, and then use the COR and ERR flags.

 

Ports

Ports

Direction

Type

Description

CKD

input

std_logic

Input clock

CHK

input

std_logic

Check link

This pin must be connected to the LSB of the output memory block – for each port requiring the ECC function.

COR

output

std_logic

One error found and corrected

ERR

output

std_logic

Errors found and not corrected

Instantiation Example

This documentation only provides the instantiation of the component.

 



NX_RAM (NG-MEDIUM & NG-LARGE)

Description

The NX_RAM component describes a synchronous True Dual Port Random Access Memory circuit of 48 Kbits available in NG-MEDIUM. The circuit supports Error Code Correction (ECC, also called EDAC – Error Detection and Correction).

The 48K-bit memory array can be simultaneously read or written by two access ports (A and B).

 

When used without EDAC, the external RAM block configuration can be set independently for the two access ports. As an example, the port A can be configured for 48Kx1, while the port B can be organized as 4Kx12.

Data inputs, addresses, control signals, clock inputs and data outputs are independent for each ports. The clocks can be synchronous or asynchronous.

 

However, simultaneous write access on both ports at the same physical address, or write access simultaneous with a read access at the same physical address are not allowed.

 

Memory ports configurations

Optional input and output behavior and pipeline registers:

By default, the RAM block do not use pipeline registers. The output delivers a valid data Taccess_time after the clock edge that samples the read address (ACS = ‘1’ and AWE = ‘0’) or BCS = ‘1’ and BWE = ‘0’).

During write cycles (ACS = ‘1’ and AWE = ‘1’) or (BCS = ‘1’ and BWE = ‘1’), the RAM block output remains with the anterior value.

However, to improve the design performance (in terms of clock frequency), the user can optionally insert two levels of pipeline registers.

  • The output pipeline allows to support higher frequencies, and reduces the apparent memory access time, at the cost of one clock cycle delay.

  • The input pipeline register level also improves the supported frequency, and reduces the apparent memory setup delay, at the cost of one additional clock cycle delay.

  • The optional input and output registers can be synchronously reset by activating the AR (A port) and/or BR (B port) inputs (active high).

In addition, the polarity of the block RAM clock as well as the one of the register clocks can be modified by the user (see NX_RAM raw_config0).

 

No ECC modes

The NO_ECC configuration mode is set by generics (raw_config1(15:12) = “0000”.

The memory is internally organized as a 2K x 24-bit array. The memory is True Dual Port. It can be simultaneously access by 2 ports (respectively called port A and port B).

Each port can access the array in several formats. Each port can have an independent configuration (address and data width), with independent data input, addresses, control signals, data output and clock. The two clocks can be synchronous or asynchronous.

The possible configuration ratios on each port can be defined either with the “std_mode” or the “raw_config1 generic. Among the available NX_RAM configurations :

 

“std_mode” values

NG-MEDIUM

“raw_config1” equivalent

NG-LARGE

“raw_config1” equivalent

 

 

 

 

NO ECC

Ports width

NO ECC

Ports width

 

 

 

"NOECC_48kx1"

0000 000 000 000 000

0000 000 000 000 000

"NOECC_24kx2"

0000 001 001 001 001

0000 001 001 001 001

"NOECC_12kx4"

0000 010 010 010 010

0000 010 010 010 010

"NOECC_6kx8"

0000 011 011 011 011

0000 011 011 011 011

"NOECC_4kx12"

0000 100 100 100 100

0000 100 100 100 100

"NOECC_2kx24"

0000 101 101 101 101

0000 101 101 101 101

"NOECC_16kx3"

Not allowed

0000 110 110 110 110

"NOECC_8kx6"

Not allowed

0000 111 111 111 111

 

 

 

In addition, the user can define several different NX_RAM configurations by directly assigning the “raw_config1” generic value, and assign the optional input and output pipeline registers with “raw_config0” generic.

However, it’s strongly recommended to select the same width for input and output data width on a same port. As an example, port A could be configured as NO ECC 2kx24, while port B could be configured as NO ECC 4kx12, with the following “raw_config1” setting :

raw_config1 => “0000” & “100” & “101” & “100” & “101”;

More on input and output data width

The input data width and output data width for both ports A and B can be set by setting generic values if the RAM block is instantiated (raw_config1(11:0)).

The figure 8 shows the physical memory organization and the dada/address lines to be used to access the array contents (output data is shown for port A only).

 

2K x 24 :

Internally, the RAM blocks are physically organized as 2K x 24-bit array. The addresses AA11 .. AA1 (or BA11 .. BA1) are used to access the 24-bit data. AI24 .. AI1 (or BI24 .. BI1) data input lines are used for write operations. A024 .. AO1 (or BO24 .. BO1) are used or data read.

4K x 12 and other organizations : 6K x 8, 12K x4, 24K x 2 and 48K x 1 (16K x 3 and 8K x 6 also supported on NG-LARGE) :

When organized as 4K x 12, the addresses AA11 .. AA1 (or BA11 .. BA1) are used to access the 24-bit data word, an additional address bit (AA12 or BA12) is used to index the lower or higher 12-bit sub words. In addition, during write, the data inputs AI12 .. AI1 (or BI12 .. BI1) are used to write the lower 12 bits, and AI24 .. AI13 (or BI24 .. BI13) are used to write the higher 12 bits. For reading, AO12 .. AO1 (or BO12 .. BO1) are used to read both lower and higher 12 bits.

As a consequence, for data write, the data input bus must be replicated one or more times on the RAM block input data pins. The following figure shows a summary for the 6 possible configurations. Only port A is shown. The rules are obviously the same for port B.

 

Note that a similar scheme can be applied to the configurations 16K x 3 and 8K x 6.

  • In 16K x 3 configuration, the 3-bit data input must be replicated 8 times

  • In 8K x 6 configuration, the 3-bit data input must be replicated 4 times

 

 

ECC modes (NG-MEDIUM & NG-LARGE)

When used with ECC, the user array size is restricted to 2K x 18. The 6 remaining bits of each internal address of 24-bit words are used to store the ECC signature of each 18-bit data.

 

During the write cycles, the ECC encoder generates a 6-bit signature for each 18-bit data to be written. The resulting 24-bit words is then stored into the specified address.

 

During read cycles, the ECC decoder can detect and correct any single bit error, or detect any double bit error.

 

The physical connections of address and input/output data lines is shown in the next figure.

 

ECC data correction in FAST mode

  • If a single bit error is found, it will be automatically detected and corrected at the RAM output port. The flags ACOR or BCOR are set during the read cycle to signal the error detection and correction. However, the internal memory array remains corrupt.

  • If a double bit error is detected, it can’t be corrected, and the flags AERR or BERR are asserted.

ECC data correction in SLOW mode

  • This mode is also called Read Repair Mode (RRM).

  • If a single bit error is found, it will be automatically detected and corrected at the RAM output port, and the memory content is automatically updated with the corrected value. The flags ACOR or BCOR are set during the user’s read cycle to signal the error detection and correction.

  • If a double bit error is detected, it can’t be corrected, but the flags AERR or BERR are asserted.

  • In order to correct a possible error during a read access, the read cycle becomes a read modify write, where the write half cycle is transparent to the user. For this, the NG-MEDIUM RAM blocks use a doubled internal frequency. This internal clock is generated by using an exclusive OR, between the main clock (CKA or CKB) and the 90° shifted clock (ACKD or BCKD) required to support the ECC SLOW mode.

  • Using ACKD and/or BCKD in ECC SLOW mode is mandatory. It must be a 90° phase shifted version of the main clock input (ACK and/or BCK). ACKD and BCKD can each be generated with ACK and BCK by using PLL and WFGs.

  • In this mode, the internal RAM block works a frequency that is double of the user’s clock. The maximum user’s clock frequency is then reduced by a factor of 2, approximately.

 

Generics

mcka_edge

type bit

default value ‘0’

This generic represents the front polarity of the clock associated to the first port of the memory. ‘0’ is for rising edge and ‘1’ for falling edge.

 

mckb_edge

type bit

default value ‘0’

This generic represents the front polarity of the clock associated to the second port of the memory. ‘0’ is for rising edge and ‘1’ for falling edge.

 

pcka_edge

type bit

default value ‘0’

This generic represents the front polarity of the clock associated to the pipeline registers of the first port. ‘0’ is for rising edge and ‘1’ for falling edge.

 

pckb_edge

type bit

default value ‘0’

This generic represents the front polarity of the clock associated to the pipeline registers of the second port. ‘0’ is for rising edge and ‘1’ for falling edge.

pipe_ia

type bit

default value ‘0’

When set to ‘1’, this generic allows to insert a pipeline register at the inputs of the A port (addresses, data inputs, ACS and AWE), when the “std_mode” generic is used. If “std_mode” is not used, the user must use the “raw_config0(3:0)” generic.

 

pipe_ib

type bit

default value ‘0’

When set to ‘1’, this generic allows to insert a pipeline register at the inputs of the B port (addresses, data inputs, BCS and BWE), when the “std_mode” generic is used. If “std_mode” is not used, the user must use the “raw_config0(3:0)” generic.

 

pipe_oa

type bit

default value ‘0’

When set to ‘1’, this generic allows to insert a pipeline register at the outputs of the A port (data outputs), when the “std_mode” generic is used. If “std_mode” is not used, the user must use the “raw_config0(3:0)” generic.

 

pipe_ob

type bit

default value ‘0’

When set to ‘1’, this generic allows to insert a pipeline register at the outputs of the B port (data outputs), when the “std_mode” generic is used. If “std_mode” is not used, the user must use the “raw_config0(3:0)” generic.

 

mem_ctxt

type string

default value “”

This generic represents the initial value of the RAM. The initial value can be optionally set by bitstream. The string contains a list of all complete bit words separated by coma.

When a word size is less than the RAM data size or when number of words is less than RAM word count, an error occurs.

When a word size exceeds RAM data size or when the number of words exceeds the RAM word count, an error occurs.

 

constant MEM_INIT_0 : string := (

"001100001110010000001111,000000000000000000001110,000001001110000000001101,000000001100000000001100," &

"000000000000000000001011,000000000000000000001010,000000000000000000001001,000000000000000000001000," &

" 512 lines of 4 x 24-bit values “ &

"000000000000000000000000,000000000000000000000000,000000000000000000000000,000000000000000000000000," &

"000000000000000000000000,000000000000000000000000,000000000000000000000000,000000000000000000000000," &

"000000111000000110000110,000111100110001110000011,010011011100001010001110,110001110010010001111000"

);

The “MEM_INIT_0” constant has been declared in a user’s package can be assigned to the “mem_ctxt” NX_RAM generic.

 

std_mode

type string

default value “”

This generic represents the predefined operating mode of the RAM. When “std_mode” is assigned, the “raw_config0” and raw_config1” generics are ignored. When empty the operating mode is defined by the 2 raw_config generics.

 

When using one of these predefined modes, the 3 raw_config generics are defined as follow:

  • raw_config0(3 downto 0) → pipe_ia & pipe_ib, pipe_oa, pipe_ob

  • raw_config1

    • FAST_2kx18 ”0011100100100100”

    • SLOW_2kx18 ”1101100100100100”

 

  • NOECC_8kx6 ”0000110110110110” -- NG-LARGE only (*)

  • NOECC_16kx3 ”0000111111111111” -- NG-LARGE only (*)

  • NOECC_2kx24 ”0000101101101101”

  • NOECC_4kx12 ”0000100100100100”

  • NOECC_6kx8 ”0000011011011011”

  • NOECC_12kx4 ”0000010010010010”

  • NOECC_24kx2 ”0000001001001001”

  • NOECC_48kx1 ”0000000000000000”

 

(*) : those configurations are allowed only for NG-LARGE (please set the generic « raw_l_extend » to ‘1’)

 

raw_config0

type bit_vector(3 downto 0)

default value b“0000”

This generic configures the optional pipeline registers on input and outputs of A and B ports:

Name

Index

Description

PB_OUT_PR_MUX

3

Port B output optional pipeline register.

‘0’: no register

‘1’: Pipe register is used

 

PA_OUT_PR_MUX

2

Port A output optional pipeline register.

‘0’: no register

‘1’: Pipe register is used

PB_IN_PR_MUX

1

Port B input optional pipeline register.

‘0’: no register

‘1’: Pipe register is used

PA_IN_PR_MUX

0

Port A input optional pipeline register.

‘0’: no register

‘1’: Pipe register is used

 

raw_config1

type bit_vector(15 downto 0)

default value b“0000000000000000”

This generic configures the following fields:

Name

Index

Description

PB_ECC_RRM

15

ECC Read Repair Mode on port B

PA_ECC_RRM

14

ECC Read Repair Mode on port A

PX_ECC_FAST

13

Fast mode ECC. Must be low if PB_ECC_RRM and PA_ECC_RRM are set to ‘1’

PX_ECC

12

Enable ECC

PB_OUT_WIDTH

11:9

B port output width

PA_OUT_WIDTH

8:6

A port output width

PB_IN_WIDTH

5:3

B port input width

PA_IN_WIDTH

2:0

A port input width

Input / output widths values depend on PX_ECC:

  • PX_ECC = 0 (ECC desactivated)

    • 000: 1-bit width

    • 001: 2-bit width

    • 010: 4-bit width

    • 011: 8-bit width

    • 100: 12-bit width

    • 101: 24-bit width

    • 110: 3-bit width

    • 111: 6-bit width

 

  • Px_ECC = 1 (all ECC modes)

    • 100: width is 18 bits

    • other values are reserved

 

The bits raw_config1(15 downto 12) are used to define the NO_ECC, ECC_FAST or ECC_SLOW modes. The following table shows the possible configuration values.

 

15

14

13

12

Comment

0

0

0

0

Normal mode (NO ECC)

0

0

0

1

Invalid configuration

0

0

1

0

Invalid configuration

0

0

1

1

ECC FAST mode (no read repair)

0

1

0

0

Invalid configuration

0

1

0

1

ECC SLOW (read repair enabled on port A)

0

1

1

0

Invalid configuration

0

1

1

1

Invalid configuration

1

0

0

0

Invalid configuration

1

0

0

1

ECC SLOW (read repair enabled on port B)

1

0

1

0

Invalid configuration

1

0

1

1

Invalid configuration

1

1

0

0

Invalid configuration

1

1

0

1

ECC SLOW (read repair enabled on both ports)

1

1

1

0

Invalid configuration

1

1

1

1

Invalid configuration

 

raw_l_enable

type bit

default value b’0’

This generic defines the FPGA family currently targeted. ‘0’ for NG-MEDIUM, ‘1’ for NG-LARGE (additional configuration modes)

 

raw_l_extend

type bit_vector(3 downto 0)

default value b“0000”

This generic is reserved for future versions.

 

Ports

Ports

Direction

Type

Description

Ports

Direction

Type

Description

ACK

input

std_logic

A port memory main clock

ACKC

input

std_logic

A port memory clock clone. Must be connected to the same clock source as ACK

ACKD

input

std_logic

A port memory 90° shifted clock. ACKD must be used when Read Repair Mode is selected on this port. It allows to internally generate a double frequency for the memory matrix, to allow read modify write during a single user’s clock cycle.

ACKR

input

std_logic

A port register clock. ACKR must be fed by a valid clock (typically ACK), if the optional input or output pipeline registers are used.

BCK

input

std_logic

B port memory main clock.

BCKC

input

std_logic

B port memory clock clone. Same comments as for ACKC

BCKD

input

std_logic

B port memory 90° shifted clock. Just as ACKD, BCKD is used when Read Repair Mode is selected on B port.

BCKR

input

std_logic

B port register clock. BCKR must be fed by a valid clock (typically BCK), if the optional input or output pipeline registers are used.

AI1 to AI24

input

std_logic

A port input data. See notes on data input width for proper operation.

BI1 to BI24

input

std_logic

B port input data. See notes on data input width for proper operation.

ACOR

output

std_logic

Goes high for one clock cycle when an error has been detected and corrected on port A

AERR

output

std_logic

Goes high for one clock cycle when an uncorrectable error has been found on port A

BCOR

output

std_logic

Goes high for one clock cycle when an error has been detected and corrected on port A

BERR

output

std_logic

Goes high for one clock cycle when an uncorrectable error has been found on port A

AO1 to AO24

output

std_logic

A port output data. See notes on data output width for proper operation

BO1 to BO24

output

std_logic

B port output data. See notes on data output width for proper operation

AA1 to AA16

input

std_logic

A port address. See notes on physical and logical addresses for proper operation

ACS

input

std_logic

A port chip select (active high)

AWE

input

std_logic

A port write enable (active high)

AR

input

std_logic

A port registers reset (active high)

BA1 to BA16

input

std_logic

B port address. See notes on physical and logical addresses for proper operation

BCS

input

std_logic

B port chip select (active high)

BWE

input

std_logic

B port write enable (active high)

BR

input

std_logic

B port registers reset (active high)

 

The ACKC port must be connected and is a clone of the memory clock (ACK).

When using one of the SLOW modes, ACKD port must be connected to a clock which is a 90° shifted version of ACK. ACKD can be generated with ACK by using 2 WFGs in the same CKG block.

The ACKR input clock is used only for the optional input and output pipeline registers. AR is the input for synchronous reset of those registers.

The BCKC and BCKD ports must be connected as described for ACKC and ACKD. BR is the synchronous reset of the optional input and output registers on port B.

 

Instantiation Example

 

Simulation

The NX_RAM VHDL simulation model is included in the NxLibrary (NxPackage.vhd). It allows to simulate any one of the possible configurations, including with ECC in FAST or SLOW modes.

NX_RAM_WRAP (NG-MEDIUM & NG-LARGE)

Description

The NX_RAM_WRAP provides an alternate way to instantiate NX_RAM. It uses the same generics as NX_RAM, and the ports are grouped as busses whenever possible.

 

Generics

std_mode : string := "";

mcka_edge : bit := '0';

mckb_edge : bit := '0';

pcka_edge : bit := '0';

pckb_edge : bit := '0';

pipe_ia : bit := '0';

pipe_ib : bit := '0';

pipe_oa : bit := '0';

pipe_ob : bit := '0';

mem_ctxt : string := "";

raw_config0 : bit_vector( 3 downto 0) := B"0000";

raw_config1 : bit_vector(15 downto 0) := B"0000000000000000"

 

Please, refer to the NX_RAM chapter for more detailed information.

 

Ports

 

Ports

Direction

Type

Description

ACK

input

std_logic

A port memory main clock

ACKD

input

std_logic

A port memory 90° shifted clock. ACKD must be used when Read Repair Mode is selected on this port. It allows to internally generate a double frequency for the memory matrix, to allow read modify write during a single user’s clock cycle.

ACKR

input

std_logic

A port register clock. ACKR must be fed by a valid clock (typically ACK), if the optional input or output pipeline registers are used.

BCK

input

std_logic

B port memory main clock.

BCKD

input

std_logic

B port memory 90° shifted clock. Just as ACKD, BCKD is used when Read Repair Mode is selected on B port.

BCKR

input

std_logic

B port register clock. BCKR must be fed by a valid clock (typically BCK), if the optional input or output pipeline registers are used.

AI(23:0)

input

std_logic_vector

A port input data. See notes on data input width for proper operation.

BI(23:0)

input

std_logic_vector

B port input data. See notes on data input width for proper operation.

ACOR

output

std_logic

Goes high for one clock cycle when an error has been detected and corrected on port A

AERR

output

std_logic

Goes high for one clock cycle when an uncorrectable error has been found on port A

BCOR

output

std_logic

Goes high for one clock cycle when an error has been detected and corrected on port A

BERR

output

std_logic

Goes high for one clock cycle when an uncorrectable error has been found on port A

AO(23:0)

output

std_logic_vector

A port output data. See notes on data output width for proper operation

BO(23:0)

output

std_logic_vector

B port output data. See notes on data output width for proper operation

AA(15:0)

input

std_logic_vector

A port address. See notes on physical and logical addresses for proper operation

ACS

input

std_logic

A port chip select (active high)

AWE

input

std_logic

A port write enable (active high)

AR

input

std_logic

A port registers reset (active high)

BA(15:0)

input

std_logic_vector

B port address. See notes on physical and logical addresses for proper operation

BCS

input

std_logic

B port chip select (active high)

BWE

input

std_logic

B port write enable (active high)

BR

input

std_logic

B port registers reset (active high)

 

 

 

Instantiation Example

 

Simulation

The NX_RAM VHDL simulation model is included in the NxLibrary (NxPackage.vhd). It allows to simulate any one of the possible configurations, including with ECC in FAST or SLOW modes.

 

I/O elements

NX_IOB

Description

The NX_IOB component describes a bidirectional port of the design. The behavior is:

 

O <= IO

IO <= I when C = ‘1’

 

Termination is active when T = ‘1’.

 

The NX_IOB can be instantiated anywhere in the design hierarchy. It allows to define buried ports (no signal appears in the ports list).

 

 

 

Generics

Note that the generic assigned to this primitive can be overridden by the addPad or addPads methods in the script file.

 

location

type string

default value Undefined (no default value)

This generic specifies the position of the physical pad in the IO ring. Example :

location => “IOB10_D09N“

 

standard

type string

default value “LCVMOS_2.5V_2mA”

This generic specifies the electrical standard of the IO, including its power supply and output current drive. The list of the possible values is described in the NanoXplore_NXmap_User_Manual. Example :

padType => “LVCMOS_2.5V_8mA“

 

drive

type string

default value “LCVMOS_2.5V_2mA”

This generic specifies the electrical standard of the IO, including its power supply and output current drive. The list of the possible values is described in the NanoXplore_NXmap_User_Manual. Example :

padType => “LVCMOS_2.5V_8mA“

 

differential

type string (“true” or “false”)

default value “false”

This generic specifies if the IO uses a differential standard. Example :

differential => ”true”

 

slewRate

type string (“Slow”, “Medium” or “Fast”)

default value “Medium”

This generic specifies slewrate of the output buffer. Example :

slewRate => ”Fast”

 

termination

type string (value in ohms – range 30 to 80)

default value ”” (no termination)

This generic specifies the value of the input impedance resistors. It’s specified in Ohms, in a range 30 to 80 Ohms. Example :

termination => ”50”

Note: Min and max values depend on the variant and the bank voltage.

 

terminationReference

type string => “floating” or “VT”

default value ”VT”

This generic specifies if the input termination resistors are floating or connected to the VT voltage reference. Can be useful for some differential input cases. Example :

termination => ”floating”

 

turbo

type string => “true” or “false”

default value “false”

This generic specifies if the input buffer is in turbo mode. Example :

turbo => ”true”

 

weakTermination

type string => “None”, “PullUp”, “PullDown” or “Keeper”

default value “None”

This generic specifies if the input pad is using weak termination impedance. Note that only ‘None’ and ‘PullUp’ are allowed in NG-MEDIUM. Example :

weakTermination => ”PullUp”

 

inputDelayOn

type string => “true” or “false”

default value “false”

This generic enables/disables delay when the pad is configured as an input. Example :

inputDelayOn => ”true”

 

inputDelayLine

type string => “0” to “63” (“” – empty string to bypass the delay line)

default value “0”

This generic specifies the number of 160 ps delay taps used on the input path. Example :

inputDelayLine => ”27”

 

outputDelayOn

type string => “true” or “false”

default value “false”

This generic enables/disables delay when the pad is configured as an output. Example :

outputDelayOn => ”true”

 

outputDelayLine

type string => “0” to “63” (“” – empty string to bypass the delay line)

default value “0”

This generic specifies the number of 160 ps delay taps used on the output path. Example :

outputDelayLine => ”35”

 

inputSignalSlope

type string => “decimal value in V/ns” (range 0.5 to 20)

default value “”

This generic has no effect on the implementation process, but it’s used by the timing analyzer. The value must be specified in Volts/ns..Example :

inputSignalSlope => ”8”

 

outputCapacity

type string “integer_value in pF” (range 0 to 40)

default value “0”

This generic has no effect on the implementation process, but it’s used by the timing analyzer. The value must be specified in ps..Example :

outpuCapacity => ”15”

 

locked

type bit => ‘0’ or ‘1’

default value ‘0’

This generic specifies if the “location” and the “termination” on the instantiated NX_IOB are done in the instantiation (locked => ‘1’) or in the Nxpython script fine (locked => ‘0’). Example :

location => ”IOB12_D4P”,

locked => ‘1’,

 

Ports

Ports

Direction

Type

Description

I

Input

std_logic

From FPGA fabric

C

Input

std_logic

Tristate control

‘0’: High impedance

‘1’: Enable output

 

 

T

Input

std_logic

Termination control

‘0’: No calibration

‘1’: calibration activated

O

output

std_logic

To FPGA fabric

IO

inout

std_logic

External pad

 

Example

This documentation only provides the instantiation of the component.

 

 

NX_IOB_I

Description

The NX_IOB_I component describes an input port of the design. The behavior is:

 

O <= IO

 

Termination is active when T = ‘1’.

 

The NX_IOB can be instantiated anywhere in the design hierarchy. It allows to define buried ports (no signal appears in the ports list).

 

 

 

Generics

Note that the generic assigned to this primitive can be overridden by the addPad or addPads methods in the script file.

 

location

type string

default value Undefined (no default value)

This generic specifies the position of the physical pad in the IO ring. Example :

location => “IOB10_D09N“

standard

type string

default value “LCVMOS_2.5V_2mA”

This generic specifies the electrical standard of the IO, including its power supply and output current drive. The list of the possible values is described in the NanoXplore_NXmap_User_Manual. Example :

padType => “LVCMOS_2.5V_8mA“

 

differential

type string => “True” or “False”

default value ”False”

This generic specifies if the IO uses a differential standard. Example :

differential => “True“

 

termination

type string => “value in ohms“ (range 30 to 80)

default value ”” (no termination)

This generic specifies the value of the input impedance resistors. It’s specified in Ohms, in a range 30 to 80 Ohms. Example :

termination => “50“

Note: Min and max values depend on the variant and the bank voltage.

 

terminationReference

type string => “floating” or “VT”

default value ”VT”

This generic specifies if the input termination resistors are floating or connected to the VT voltage reference. Can be useful for some differential input cases. Example :

termination => ”floating”

 

turbo

type string => “true” or “false”

default value “false”

This generic specifies if the input buffer is in turbo mode. Example :

turbo => ”true”

 

weakTermination

type string => “None”, “PullUp”, “PullDown” or “Keeper”

default value “None”

This generic specifies if the input pad is using weak termination impedance. Note that only ‘None’ and ‘PullUp’ are allowed in NG-MEDIUM. Example :

weakTermination => “PullUp“

 

inputDelayOn

type string => “true” or “false”

default value “false”

This generic enables/disables delay when the pad is configured as an input. Example :

inputDelayOn => ”true”

 

inputDelayLine

type string => “0” to “63” (“” – empty string to bypass the delay line)

 

default value “0”

This generic specifies the number of 160 ps delay taps used on the input path. Example :

inputDelayLine => “27“

 

inputSignalSlope

type string => “decimal value in V/ns” (range 0.5 to 20)

default value “”

This generic has no effect on the implementation process, but it’s used by the timing analyzer. The value must be specified in Volts/ns..Example :

inputSignalSlope => ”8”

 

locked

type bit => ‘0’ or ‘1’

default value ‘0’

This generic specifies if the “location” and the “termination” on the instantiated NX_IOB are done in the instatiation (locked => ‘1’) or in the Nxpython script fine (locked => ‘0’). Example :

location => ”IOB12_D4P”,

locked => ‘1’,

 

 

 

Ports

Ports

Direction

Type

Description

C

Input

Std_logic

Not used. Must be left “open” or unconnected

T

Input

std_logic

Termination control

‘0’ : No termination

‘1’ : Input termination activated

O

output

std_logic

From FPGA fabric

IO

Input

std_logic

External pad

 

Example

This documentation only provides the instantiation of the component.

 

 

NX_IOB_O

Description

The NX_IOB_O component describes an output port of the design. The behavior is:

 

IO <= I when C = ‘1’ else ‘Z’

 

Termination is active when T = ‘1’.

 

The NX_IOB can be instantiated anywhere in the design hierarchy. It allows to define buried ports (no signal appears in the ports list).

 

 

 

Generics

Note that the generic assigned to this primitive can be overridden by the addPad or addPads methods in the script file.

 

location

type string

default value Undefined (no default value)

This generic specifies the position of the physical pad in the IO ring. Example :

location => “IOB10_D09N“

standard

type string

default value “LCVMOS_2.5V_2mA”

This generic specifies the electrical standard of the IO, including its power supply and output current drive. The list of the possible values is described in the NanoXplore_NXmap_User_Manual. Example :

padType => “LVCMOS_2.5V_8mA“

 

 

differential

type string => “True” or “False”

default value “False“

This generic specifies if the IO uses a differential standard. Example :

differential => “True“

 

slewRate

type string => “Slow”, “Medium” or “Fast”

default value “Medium”

This generic specifies slewrate of the output buffer. Example :

slewRate => “Fast“

 

weakTermination

type string => “None”, “PullUp”, “PullDown” or “Keeper”

default value “None”

This generic specifies if the input pad is using weak termination impedance. Note that only “None“ and “PullUp“ are allowed in NG-MEDIUM. Example :

weakTermination => “PullUp“

 

outputDelayOn

type string => “true” or “false”

default value “false”

This generic enables/disables delay when the pad is configured as an output. Example :

outputDelayOn => ”true”

 

outputDelayLine

type string => “0” to “63” (“” – empty string to bypass the delay line)

default value “0”

This generic specifies the number of 160 ps delay taps used on the output path. Example :

outputDelayLine => “35”

 

outputCapacity

type string “integer value in pF” (range 0 to 40)

default value “”

This generic has no effect on the implementation process, but it’s used by the timing analyzer. The value must be specified in ps..Example :

outpuCapacity => “15“

 

locked

type bit => ‘0’ or ‘1’

default value ‘0’

This generic specifies if the “location” and the “termination”on the instantiated NX_IOB are done in the instatiation (locked => ‘1’) or in the Nxpython script fine (locked => ‘0’). Example :

location => ”IOB12_D4P”,

locked => ‘1’,

 

 

Ports

Ports

Direction

Type

Description

I

input

std_logic

From FPGA fabric

C

input

std_logic

Tristate control (‘0’ for High Z)

T

input

std_logic

Not used. Must be left “open” or unconnected

IO

output

std_logic

External pad

 

 

 

Example

This documentation only provides the instantiation of the component.

 

 

SERializers and DESerializers

Introduction

The NG-MEDIUM complex I/O banks provide serializers and deserializer features.

Each serializer or deserializer can use a serialization factor of 2, 3, 4 or 5.

In addition in each I/O pair, the serializers/deserializers associated to the “_P” pad can be chained with its neighbor (associated to the “_N” pad) allowing thus serialization/deserialization factors of 6, 7, 8, 9 and 10.

The serializer/deserializer data path requires two clocks: bit clock (Fast clock – FCK) and word clock (Slow clock – SCK).

Serializers include optional output delay lines for both output and tri-state command. Although output delay lines can be dynamically controlled, serializer delays are usually configured in static mode – most often no delay.

Deserializers require a proper data/clock alignment mechanism for safe sampling, as well as word alignment to recover the original words. Data/clock alignment requires a dynamic control of the delay lines to adjust the phase relationship of the sampled data and the fast clock. This procedure is called Dynamic Phase Alignment (DPA). It requires a training sequence.

NG-MEDIUM complex IO banks provide hardware support for DPA. The dynamic control of the delay lines requires an additional clock to read or write into the delay registers. This clock is called DCK. It can be synchronous or asynchronous with the data path clocks SCK and FCK.

 

All I/O related delay lines have 0 to 63 x 160 ps steps delays.

 

SERDES architecture overview

The serializers/deserializers architecture contains two main blocks :

  • Data path

  • Delay control path

 

 

DPA : Dynamic Phase Adjustment

 

NG-MEDIUM architecture provides hardware support for Dynamic Phase Adjustment on NX_DES. The following describes how to implement the adjustment procedure.

In the complex banks, all I/Os include three user’s selectable and adjustable delay lines that can be selected with “DS(1:0)” sub-address input. Those registers can be read and written with a simple microprocessor-like interface.

Each NX_DES or NX_SER include three delay lines, respectively for output (and tri-state control), input path and DPA path delays. The delay value on each one of those three paths (number of 160 ps delay taps) is defined by the value written into the corresponding delay register.

  • The output (and tri-state control) delay register controls the delay inserted on the output data path.

  • The input delay register controls the delay inserted between the input pad and the input register.

  • The DPA delay register controls the delay inserted between the input pad and the DPA input register.

The DPA logic allows to generate flags (FLD and FLG) to inform about the data input and fast clock relative phase :

  • FLD : this flag goes high when a transition on the data line at the output of the DPA delay line, occurs between the falling and the rising edge of the sampling clock (FCK, fast clock).

  • FLG : this flag goes high when a transition on the data line at the output of the DPA delay line, occurs between the rising and the falling edge of the sampling clock (FCK, fast clock).

  • FZ : Active low flags reset

  • By modifying the value of the DPA delay line, data/clock relationship can be analyzed by monitoring the FLD and FLG flags – and then deduce the optimal delay value to be written to the input delay register.

  • The following figures show the FLD and FLG flags behavior versus the transition detection on the DPA delay line output.

 

 

 

Write and read accesses to the delay registers can be easily managed with the following signals :

  • DCK : delay registers clock (can be asynchronous with SCK/FCK). Usually 2 to 20 MHz. Write operations occur on DCK rising edge.

  • DID(4:0) : address identifier of the considered I/O in the complex bank (0 to 29).

  • DRA(4:0) : address of the I/O in the considered complex bank (0 to 29). Note that when DRA = DID, the DRO outputs, as well as FLD and FLG flags outputs of the considered I/O go to low impedance (allowing thus to be read by the fabric).

  • DS(1:0) : allow to select the destination register into the DRA selected I/O. See next table for details.

DS value

Selected delay register

 

 

00

Output (and tri-state control) delay register

01

Input delay register

10

DPA delay register

11

Reserved

 

  • DRI(5:0) :value to be written into the selected register.

  • DRL : active high load (write enable)

 

NanoXplore recommends to use NXcore – customizable IP Core generator - to use deserializers with automatic data/clock phase alignment and word alignment.

The IP Core uses an automatic procedure – launched by the user at any time – to proceed to the input delays calibration and word alignment on all DESerializers of the same group.

The IP Core also generates the required clocks (SCK, FCK and DCK) from a word clock input. It requires using the neighboring ClocK Generator block (CKG1 for I/O complex banks 11 & 12 for example).

Handshake signals with the transmitter and calibration status are provided to the user application. Among the available signals :

  • LAUNCH_CALIB (input) : launches the calibration process (on a rising edge)

  • TRAINING_REQ_OUT (output) : The IP Core requests the transmitter to send the serialized “TrainingValue” to the DESerializer(s).

  • TRAINING_ACK_IN (input) : The transmitter is ready and sends the serialized “TrainingValue”

  • TRAINING_REQ_IN (input) : if the IP Core is used as transmitter, the receiver might require a calibration sequence where the transmitter must send the serialized “TrainingValue”. TRAINING_REQ_IN is the request input of the transmitter.

  • TRAINING_ACK_OUT (output) : When the transmitter receives a request from the receiver, it sends the serialized “TrainingValue” and activates the TRAINING_ACK output to the receiver.

  • CALIB_DONE (output) : goes high to state that the calibration process is done.

  • CALIB_ERROR (output) : Active high status bit to state that the calibration was not successful.

 

NX_DES

Description

The NX_DES is a high performance DESerializer. The complex banks allows to configure the I/Os as DESerializers with deserialization factor from 3 to 5. Higher deserialization factors (6, 7, 8, 9 and 10) can be achieved by combining the two deserializers of a differential IO pair.

 

Generics

data_size

type integer

default value Undefined (no default value)

This generic specifies the deserialization factor. Example :

data_size => 8

 

location

type string

default value Undefined (no default value)

This generic specifies the position of the physical pad in the IO ring. Example :

location => “IOB12_D01P“

 

padType

type string

default value “LCVMOS_2.5V_2mA“

This generic specifies the electrical standard of the IO, including its power supply and output current drive. The list of the possible values is described in the NanoXplore_NXmap_User_Manual. Example :

padType => “LVCMOS_1.5V_8mA“

 

differential

type string => “True” or “False”

default value ”False”

This generic specifies if the IO uses a differential standard. Example :

differential => “True“

 

termination

type string => “value in ohms“ (range 30 to 80)

default value ”” (no termination)

This generic specifies the value of the input impedance resistors. It’s specified in Ohms, in a range 30 to 80 Ohms. Example :

termination => “50“

Note: Min and max values depend on the variant and the bank voltage.

 

terminationReference

type string => “floating” or “VT”

default value ”VT”

This generic specifies if the input termination resistors are floating or connected to the VT voltage reference. Can be useful for some differential input cases. Example :

termination => ”floating”

 

turbo

type string => “true” or “false”

default value “false”

This generic specifies if the input buffer is in turbo mode. Example :

turbo => ”true”

 

weakTermination

type string => “None”, “PullUp”, “PullDown” or “Keeper”

default value “None”

This generic specifies if the input pad is using weak termination impedance. Note that only ‘None’ and ‘PullUp’ are allowed in NG-MEDIUM. Example :

weakTermination => “PullUp“

 

inputDelayLine

type string => “0” to “63” (“” – empty string with no character or space for dynamic

delay)

default value “0” (set to “” (empty string) by NXcore to allow dynamic delay for calibation

process)

This generic specifies the number of 160 ps delay taps used on the input path.

Example for dynamic delay (required for calibration process) :

inputDelayLine => “ “, -- Dynamic input delay (FLD and FLG are available)

 

Example for static delay (no calibration can be carried out) :

inputDelayLine => “27“, -- Static input delay (FLD and FLG are not available)

 

 

 

inputSignalSlope

type string => “decimal value in V/ns” (range 0.5 to 20)

default value “”

This generic has no effect on the implementation process, but it’s used by the timing analyzer. The value must be specified in Volts/ns..Example :

inputSignalSlope => ”8”

 

 

Ports

 

Ports

Direction

Type

Description

FCK

In

Std_logic

Fast clock (bit clock)

SCK

In

Std_logic

Slow clock (word clock)

R

In

Std_logic

 

Active high Reset

IO

In

Std_logic

Input pad

O

Out

Std_logic_vector

(data_size-1 downto 0)

Sampled word to FPGA fabric

 

 

 

 

DCK

In

Std_logic

Delay lines management registers clock

DRL

In

Std_logic

Delay Registers Load

DIG

In

Std_logic

‘0’ for Multicast write (*)

‘1’ for normal operation

DS

In

Std_logic_vector

(1 downto 0)

Delay Select :

00 => out & tri-state regs

01 => input delay register

10 => DPA delay register

11 => RESERVED

 

DRA

In

Std_logic_vector

(4 downto 0)

Delay address (0 to 29)

DRI

In

Std_logic_vector

(5 downto 0)

Data input to delay registers

DRO

Out (with tri-state)

Std_logic_vector

(5 downto 0)

Delay value being read

Active when DRA = DID else high impedance

DID

Out

Std_logic_vector

(4 downto 0)

Pad address identification

FZ

In

Std_logic

Active low Flags Reset

FLD

Out (with tri-state)

Std_logic

Early capture flag Active when DRA = DID else high impedance

FLG

Out (with tri-state)

Std_logic

Late capture flag Active when DRA = DID else high impedance

(*) : When DIG is low, any write cycle will write the same value into all corresponding registers – selected by DS(1:0) - of the 30 I/Os in the current complex I/O bank.

DIG must be high for normal operation, particularly for delay calibration.

 

NX _SER

Description

The NX_SER is a high performance SERializer. The complex banks allows to configure the I/Os as SERializers with serialization factor from 3 to 5. Higher serialization factors (6, 7, 8, 9 and 10) can be achieved by combining the two serializers of a differential IO pair.

 

Generics

 

data_size

type integer

default value Undefined (no default value)

This generic specifies the serialization factor. Example :

data_size => 8

 

location

type string

default value Undefined (no default value)

This generic specifies the position of the physical pad in the IO ring. Example :

location => “IOB10_D09N“

 

padType

type string

default value “LCVMOS_2.5V_2mA“

This generic specifies the electrical standard of the IO, including its power supply and output current drive. The list of the possible values is described in the NanoXplore_NXmap_User_Manual. Example :

padType => “LVCMOS_1.5V_8mA“

 

differential

type string => “True” or “False”

default value “False“

This generic specifies if the IO uses a differential standard. Example :

differential => “True“

 

slewRate

type string => “Slow”, “Medium” or “Fast”

default value “Medium”

This generic specifies slewrate of the output buffer. Example :

slewRate => “Fast“

 

outputDelayLine

type string => “0” to “63” (“” – empty string to bypass the delay line)

default value “0”

This generic specifies the number of 160 ps delay taps used on the output path. Example :

outputDelayLine => “35”

 

outputCapacity

type string “integer value in pF” (range 0 to 40)

default value “”

This generic has no effect on the implementation process, but it’s used by the timing analyzer. The value must be specified in ps..Example :

outpuCapacity => “15“

 

 

Ports

 

Ports

Direction

Type

Description

FCK

In

Std_logic

Fast clock (bit clock)

SCK

In

Std_logic

Slow clock (word clock)

R

In

Std_logic

 

Active high Reset

IO

Out

Std_logic

Input pad

I

In

Std_logic_vector

(data_size-1 downto 0)

Data to be serialized from fabric

 

 

 

 

DCK

In

Std_logic

Delay lines management registers clock

DRL

In

Std_logic

Delay Registers Load

DS

In

Std_logic_vector

(1 downto 0)

Delay Select :

00 => out & tri-state regs

01 => input delay register

10 => DPA delay register

11 => RESERVED

 

DRA

In

Std_logic_vector

(4 downto 0)

Delay address (0 to 29)

DRI

In

Std_logic_vector

(5 downto 0)

Data input to delay registers

DRO

Out (with tri-state)

Std_logic_vector

(5 downto 0)

Delay value being read

Active when DRA = DID, else high-impedance)

DID

Out

Std_logic_vector

(4 downto 0)

Pad address identifier (0 to 29

 

 

 

 

Reserved

There are some other components defined in NX library that are reserved for post synthesis and post place & route simulation. These components cannot be instantiated in pre synthesis VHDL.

 

The reserved components are:

  • NX_BUFFER

  • NX_CSC

  • NX_SCC

 

 

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