HDL
HDL
  • JESD204B/C Link Transmit Peripheral
    • Features
    • Files
    • Block Diagram
    • AXI JESD204 TX Synthesis Configuration Parameters
    • JESD204 TX Synthesis Configuration Parameters
    • AXI JESD204 TX Signal and Interface Pins
    • JESD204 TX Signal and Interface Pins
    • Register Map
    • Theory of Operation
      • Interfaces and Signals
        • Register Map Configuration Interface
        • JESD204B Control Signals
        • Transceiver Interface (TX_PHYn)
        • User Data Interface (TX_DATA)
      • Configuration Interface
        • Peripheral Identification and HDL Synthesis Settings
        • Interrupt Handling
        • Link Control
        • Multi-link Control
        • Link Configuration
        • ILAS Configuration Data
        • SYSREF Handling
        • Link Status
        • Manual Synchronization Request
        • Clock Monitor
      • Interrupts
    • 8B/10B Link
      • 8B/10B Link State Machine
        • Wait Phase (WAIT)
        • Code Group Synchronization Phase (CGS)
        • Initial Lane Alignment Sequence Phase (ILAS)
        • User Data Phase (DATA)
      • 8B/10B Multi-endpoint TX link establishment
      • Diagnostics
    • 64B/66B Link
    • Dual clock operation
    • Software Support
    • Restrictions
    • Supported Devices
      • JESD204B Digital-to-Analog Converters
      • JESD204B RF Transceivers
      • JESD204B/C Mixed-Signal Front Ends
    • Technical Support
    • More Information
HDL
  • User Guide
    • Introduction
    • Git repository
    • Releases
    • Build an HDL project
    • Build the BOOT.BIN
    • Build the Intel Boot Image
    • HDL architecture
    • IP cores
      • Creating a new IP
      • Use ADI IPs into your own project
      • Interfaces
      • Generic AXI ADC
      • Generic AXI DAC
    • Porting HDL projects
    • Customize HDL projects
    • HDL coding guidelines
    • Documentation guidelines
    • Contributing to HDL
    • Third party forks
  • IP Cores
    • I3C Controller
      • Host Interface
      • Core Module
      • Interface
    • JESD204 Interface Framework
      • Generic JESD204 block designs
      • JESD204B/C Link Transmit Peripheral
      • JESD204B/C Link Receive Peripheral
      • ADC JESD204B/C Transport Peripheral
      • DAC JESD204B/C Transport Peripheral
      • Xilinx FPGAs Transceivers Wizard
      • Troubleshooting JESD204 TX links
    • SPI Engine
      • Execution Module
      • AXI Module
      • Offload Module
      • Interconnect Module
      • Control Interface
      • Offload Control Interface
      • SPI Bus Interface
      • Instruction Set Specification
      • Pipeline Delays
      • Tutorial - PulSAR ADC
    • AXI AD35XXR
    • AXI AD408x
    • AXI AD485x
    • AXI AD7405
    • AXI AD7606x
    • AXI AD7616
    • AXI AD7768
    • AXI AD777x
    • AXI AD9265
    • AXI AD9361
    • AXI AD9467
    • AXI AD9783
    • AXI AD9963
    • AXI ADA4355
    • AXI ADAQ8092
    • AXI ADRV9001
    • AXI LTC235X
    • AXI LTC2387
    • Data Offload
    • AXI DMAC
    • AXI HDMI RX
    • AXI HDMI TX
    • AXI ADC Decimate
    • AXI ADC Trigger
    • AXI ADXCVR
    • AXI CLK Generator
    • AXI Clock Monitor
    • AXI DAC Interpolate
    • AXI Fan Control
    • AXI Laser Driver
    • AXI Logic Analyzer
    • AXI PWM Generator
    • AXI System ID
    • AXI TDD
    • CN0363
      • CN0363 DMA Sequencer
      • CN0363 Phase Data Sync
    • AD Direct Digital Synthesis
    • Corundum
    • AXI Stream FIFO
    • Asymmetric AXI Stream FIFO
    • Util Extract
    • Util MII to RMII
    • Channel CPACK Utility
    • Channel UPACK Utility
    • Util RFIFO
    • Util Sigma Delta SPI
    • Util VAR FIFO
    • Util WFIFO
    • AMD Xilinx Specific IPs
      • UTIL_ADXCVR
    • AXI AD9144 (OBSOLETE)
    • AXI AD9371 (OBSOLETE)
    • AXI AD9643 (OBSOLETE)
    • AXI AD9671 (OBSOLETE)
  • Projects
    • AD-GMSL2ETH-SL
    • AD-QUADMXFE1-EBZ
    • AD353XR
    • AD35XXR-EVB
    • AD4052-ARDZ
    • AD408X-FMC-EVB
    • AD4110-SDZ
    • AD411x-AD717x
    • AD4134-FMC
    • AD4170-ASDZ
    • AD4630-FMC
    • AD469X-EVB
    • AD485X-FMCZ
    • AD488X-FMC-EVB
    • AD5758-SDZ
    • AD5766-SDZ
    • AD57XX-ARDZ
    • AD6676EVB
    • AD7124-ASDZ
    • AD7134-FMC
    • AD719X-ASDZ
    • AD738X-FMC
    • AD7405-FMC
    • AD7606X-FMC
    • AD7616-SDZ
    • AD7768-1-EVB
    • AD7768-EVB
    • AD777X-FMCZ
    • AD9081-FMCA-EBZ
    • AD9081-FMCA-EBZ-X-BAND
    • AD9083-EVB
    • AD9084-EBZ
    • AD916x-FMC
    • AD9208-DUAL-EBZ
    • AD9209-FMCA-EBZ
    • AD9213-DUAL-EBZ
    • AD9213-EVB
    • AD9265-FMC
    • AD9434-FMC
    • AD9467-FMC
    • AD9656-FMC
    • AD9694-FMC
    • AD9695-FMC
    • AD9783-EBZ
    • ADA4355-FMC
    • ADAQ7980-SDZ
    • ADAQ8092-FMC
    • ADMX6001-EBZ
    • ADRV9001
    • ADRV9001-DUAL
    • ADRV9009
    • ADRV9009-ZU11EG
    • ADRV9026
    • ADRV904x
    • ADRV9361Z7035
    • ADRV9364Z7020
    • ADRV9371x
    • ADV7511
    • ADV7513
    • ARRADIO
    • CN0363
    • CN0506
    • CN0540
    • CN0561
    • CN0577
    • CN0579
    • CN0585
    • DAC-FMC-EBZ
    • DAQ2
    • DAQ3
    • DC2677A
    • FMCOMMS2/3/4
    • FMCOMMS5
    • FMCOMMS8
    • FMCOMMS11
    • JUPITER-SDR
    • M2K
    • MAX96724
    • PLUTO
    • PULSAR-ADC
    • PULSAR-LVDS-ADC
    • AD9739A-FMC (OBSOLETE)
    • AD-FMCLIDAR1-EBZ (OBSOLETE)
    • FMCADC2 (OBSOLETE)
    • FMCADC5 (OBSOLETE)
    • FMCJESDADC1 (OBSOLETE)
    • IMAGEON (OBSOLETE)
  1. IP Cores
  2. JESD204 Interface Framework

JESD204B/C Link Transmit Peripheral

s_axis_axi_aclks_axi_aresetntx_ilas_configtx_eventtx_statuscore_clkcore_reset_extdevice_clktx_cfgtx_ctrlirqcore_resetdevice_resetaxi_jesd204_tx

The ADI JESD204B/C Link Transmit Peripheral implements the Link layer handling of a JESD204 transmit logic device. Implements the 8B/10B based Link layer defined in JESD204C standard that is similar to the Link layer defined in JESD204B.

This includes handling of the SYSREF and SYNC~ and controlling the link state machine accordingly, as well as performing per lane scrambling and character replacement.

It has been designed for interoperability with ADI JESD204B DAC converter products. It implements the 64B/66B-based Link layer defined in the JESD204C standard. This includes handling of the SYSREF, per lane encoding of sync header, scrambling as per data multi-block CRC generation.

The type of Link layer is selectable during implementation phase through the LINK_MODE synthesis parameter.

To form a complete JESD204 transmit logic device, it has to be combined with a PHY layer and transport layer peripheral.

Features

  • Backwards compatibility with JESD204B;

  • 64B/66B Link layer defined in JESD204C;

  • Subclass 0 and Subclass 1 support;

  • Deterministic Latency (for Subclass 1 operation);

  • Runtime re-configurability through memory-mapped register interface (AXI4);

  • Interrupts for event notification;

  • Diagnostics;

  • Max Lanerate with 8B/10B mode: 15 Gbps;

  • Max Lanerate with 64B/66B mode: 32 Gbps;

  • Low Latency;

  • Independent per lane enable/disable.

Files

Important

To use this wrapper in your project, you need to use the procedure adi_tpl_jesd204_tx_create to instantiate it.

Name

Description

axi_jesd204_tx.v

Verilog source for the peripheral.

axi_jesd204_tx_ip.tcl

TCL script to generate the Vivado IP-integrator project for the peripheral.

Block Diagram

JESD204B/C Tx Link Layer

AXI JESD204 TX Synthesis Configuration Parameters

Name

Description

Default Value

Choices/Range

ID

Instance identification number.

0

NUM_LANES

Maximum number of lanes supported by the peripheral.

1

NUM_LINKS

Maximum number of links supported by the peripheral.

1

LINK_MODE

Decoder selection of the link layer. 1 - 8B/10B mode; 2 - 64B/66B mode.

1

64B66B (2), 8B10B (1)

ENABLE_LINK_STATS

Enable Link Stats.

0

DATA_PATH_WIDTH

Data path width in bytes. Set it 4 in case of 8B/10B, 8 in case of 64B/66B.

4

JESD204 TX Synthesis Configuration Parameters

Name

Description

Default Value

Choices/Range

NUM_LANES

Maximum number of lanes supported by the peripheral.

1

NUM_LINKS

Maximum number of links supported by the peripheral.

1

NUM_OUTPUT_PIPELINE

Num Output Pipeline.

0

LINK_MODE

Decoder selection of the link layer. 1 - 8B/10B mode; 2 - 64B/66B mode.

1

64B66B (2), 8B10B (1)

DATA_PATH_WIDTH

Data path width in bytes. Set it to 4 in case of 8B/10B, 8 in case of 64B/66B.

4

TPL_DATA_PATH_WIDTH

Data path width in bytes towards transport layer. Must be greater or equal to DATA_PATH_WIDTH. Must be a power of 2 integer multiple of the F parameter.

4

ENABLE_CHAR_REPLACE

Enable Char Replace.

'b0

ASYNC_CLK

Set this parameter to 1 if the link clock and the device clocks have different frequencies, or if they have the same frequency but a different source. If set, synchronizing logic and a gearbox of ratio DATA_PATH_WIDTH:TPL_DATA_PATH_WIDTH is inserted to do the rate conversion. If not set, TPL_DATA_PATH_WIDTH must match DATA_PATH_WIDTH, the same clock must be connected to clk and device_clk inputs.

1

SYSREF_IOB

Place SYSREF in IOB.

True

AXI JESD204 TX Signal and Interface Pins

Physical Port

Logical Port

Direction

Dependency

s_axi_awaddr AWADDR

in [13:0]

s_axi_awprot AWPROT

in [2:0]

s_axi_awvalid AWVALID

in

s_axi_awready AWREADY

out

s_axi_wdata WDATA

in [31:0]

s_axi_wstrb WSTRB

in [3:0]

s_axi_wvalid WVALID

in

s_axi_wready WREADY

out

s_axi_bresp BRESP

out [1:0]

s_axi_bvalid BVALID

out

s_axi_bready BREADY

in

s_axi_araddr ARADDR

in [13:0]

s_axi_arprot ARPROT

in [2:0]

s_axi_arvalid ARVALID

in

s_axi_arready ARREADY

out

s_axi_rdata RDATA

out [31:0]

s_axi_rresp RRESP

out [1:0]

s_axi_rvalid RVALID

out

s_axi_rready RREADY

in

Physical Port

Logical Port

Direction

Dependency

s_axi_aclk CLK

in

Physical Port

Logical Port

Direction

Dependency

s_axi_aresetn RST

in

Physical Port

Logical Port

Direction

Dependency

core_cfg_lanes_disable lanes_disable

out [0:0]

core_cfg_links_disable links_disable

out [0:0]

core_cfg_octets_per_multiframe octets_per_multiframe

out [9:0]

core_cfg_octets_per_frame octets_per_frame

out [7:0]

core_cfg_continuous_cgs continuous_cgs

out

core_cfg_continuous_ilas continuous_ilas

out

core_cfg_skip_ilas skip_ilas

out

core_cfg_mframes_per_ilas mframes_per_ilas

out [7:0]

core_cfg_disable_char_replacement disable_char_replacement

out

core_cfg_disable_scrambler disable_scrambler

out

device_cfg_octets_per_multiframe device_octets_per_multiframe

out [9:0]

device_cfg_octets_per_frame device_octets_per_frame

out [7:0]

device_cfg_beats_per_multiframe device_beats_per_multiframe

out [7:0]

device_cfg_lmfc_offset device_lmfc_offset

out [7:0]

device_cfg_sysref_oneshot device_sysref_oneshot

out

device_cfg_sysref_disable device_sysref_disable

out

Physical Port

Logical Port

Direction

Dependency

core_ilas_config_rd rd

in

core_ilas_config_addr addr

in [1:0]

core_ilas_config_data data

out [31:0]

Physical Port

Logical Port

Direction

Dependency

device_event_sysref_alignment_error sysref_alignment_error

in

device_event_sysref_edge sysref_edge

in

Physical Port

Logical Port

Direction

Dependency

core_status_state state

in [1:0]

core_status_sync sync

in [0:0]

status_synth_params0 synth_params0

in [31:0]

status_synth_params1 synth_params1

in [31:0]

status_synth_params2 synth_params2

in [31:0]

Physical Port

Logical Port

Direction

Dependency

core_ctrl_manual_sync_request manual_sync_request

out

Physical Port

Logical Port

Direction

Dependency

irq INTERRUPT

out

Physical Port

Direction

Dependency

Description

core_clk

in

Bus tx_status_tx_event_tx_ilas_config_tx_cfg_tx_ctrl is synchronous to this clock domain.

core_reset_ext

in

core_reset

out

Bus tx_status_tx_event_tx_ilas_config_tx_cfg_tx_ctrl is synchronous to this reset signal.

device_clk

in

Device clock for the JESD204 interface. Its frequency must be link clock * DATA_PATH_WIDTH / TPL_DATA_PATH_WIDTH

device_reset

out

Reset active high synchronous with the Device clock.

JESD204 TX Signal and Interface Pins

Physical Port

Logical Port

Direction

Dependency

tx_valid TVALID

in

tx_ready TREADY

out

tx_data TDATA

in [31:0]

Physical Port

Logical Port

Direction

Dependency

cfg_lanes_disable lanes_disable

in [0:0]

cfg_links_disable links_disable

in [0:0]

cfg_octets_per_multiframe octets_per_multiframe

in [9:0]

cfg_octets_per_frame octets_per_frame

in [7:0]

cfg_continuous_cgs continuous_cgs

in

cfg_continuous_ilas continuous_ilas

in

cfg_skip_ilas skip_ilas

in

cfg_mframes_per_ilas mframes_per_ilas

in [7:0]

cfg_disable_char_replacement disable_char_replacement

in

cfg_disable_scrambler disable_scrambler

in

device_cfg_octets_per_multiframe device_octets_per_multiframe

in [9:0]

device_cfg_octets_per_frame device_octets_per_frame

in [7:0]

device_cfg_beats_per_multiframe device_beats_per_multiframe

in [7:0]

device_cfg_lmfc_offset device_lmfc_offset

in [7:0]

device_cfg_sysref_oneshot device_sysref_oneshot

in

device_cfg_sysref_disable device_sysref_disable

in

Physical Port

Logical Port

Direction

Dependency

ilas_config_rd rd

out

ilas_config_addr addr

out [1:0]

ilas_config_data data

in [31:0]

Physical Port

Logical Port

Direction

Dependency

device_event_sysref_alignment_error sysref_alignment_error

out

device_event_sysref_edge sysref_edge

out

Physical Port

Logical Port

Direction

Dependency

status_state state

out [1:0]

status_sync sync

out [0:0]

status_synth_params0 synth_params0

out [31:0]

status_synth_params1 synth_params1

out [31:0]

status_synth_params2 synth_params2

out [31:0]

Physical Port

Logical Port

Direction

Dependency

ctrl_manual_sync_request manual_sync_request

in

Physical Port

Logical Port

Direction

Dependency

phy_data txdata

out [31:0]

phy_charisk txcharisk

out [3:0]

phy_header txheader

out [1:0]

Physical Port

Direction

Dependency

Description

clk

in

Link clock for the JESD204 interface. Must be line clock/40 for correct operation in 8B/10B mode, line clock/66 in 64B/66B mode. Bus tx_cfg_tx_ilas_config_tx_event_tx_status_tx_ctrl is synchronous to this clock domain.

reset

in

Reset active high synchronous with the Link clock. Bus tx_cfg_tx_ilas_config_tx_event_tx_status_tx_ctrl is synchronous to this reset signal.

device_clk

in

Bus tx_data is synchronous to this clock domain.

device_reset

in

Bus tx_data is synchronous to this reset signal.

sysref

in

JESD204 SYSREF signal.

lmfc_edge

out

lmfc_clk

out

sync

in [0:0]

LINK_MODE = 1

sync[m-1:0] is JESD204B SYNC~ (or SYNC_N) signal, available in 8B/10B mode. (0 <= n < NUM_LINKS)

tx_eof

out [3:0]

tx_sof

out [3:0]

tx_somf

out [3:0]

tx_eomf

out [3:0]

Register Map

DWORD

BYTE

Reg Name

Description

BITS

Field Name

Type

Default Value

Description

0x0 0x0 VERSION

Version of the peripheral. Follows semantic versioning. Current version 1.03.a.

[31:16] VERSION_MAJOR RO 0x0001

[15:8] VERSION_MINOR RO 0x03

[7:0] VERSION_PATCH RO 0x61

0x1 0x4 PERIPHERAL_ID

[31:0] PERIPHERAL_ID RO

Value of the ID configuration parameter.

0x2 0x8 SCRATCH

[31:0] SCRATCH RW 0x00000000

Scratch register useful for debug.

0x3 0xc IDENTIFICATION

[31:0] IDENTIFICATION RO 0x32303454

Peripheral identification (‘2’, ‘0’, ‘4’, ‘T’).

0x4 0x10 SYNTH_NUM_LANES

[31:0] SYNTH_NUM_LANES RO

Number of supported lanes.

0x5 0x14 SYNTH_DATA_PATH_WIDTH

[31:16] RESERVED RO 0x0000

[15:8] TPL_DATA_PATH_WIDTH RO 0x02

Data path width in octets at Transport Layer interface. Available starting from version 1.06.a;

[7:0] SYNTH_DATA_PATH_WIDTH RO 0x02

Log2 of internal data path width in octets. Represents the datapath width towards the physical interface.

0x6 0x18 SYNTH_1

Core description register.

[31:19] RESERVED RO 0x0000

[18] ENABLE_CHAR_REPLACE RO 0x0

This bit reflects the presence of character replacement insertion logic for cases when scrambling is disabled. Available starting from version 1.06.a;

[12] ASYNC_CLK RO ASYNC_​CLK

This bit is set if link clock and device clock are connected to different sources. This is useful for supporting modes where datapath width is not integer multiple of F. Available starting from version 1.06.a;

[9:8] ENCODER RO

Encoder presence: 01 - 8B10B encoder \ 10 - 64B66B encoder

[7:0] NUM_LINKS RO

Maximum supported links. Valid for 8B/10B link.

0x20 0x80 IRQ_ENABLE

[31:0] IRQ_ENABLE RW 0x00000000

Interrupt enable.

0x21 0x84 IRQ_PENDING

[31:0] IRQ_PENDING RW1CV 0x00000000

Pending and enabled interrupts.

0x22 0x88 IRQ_SOURCE

[31:0] IRQ_SOURCE RW1CV 0x00000000

Pending interrupts.

0x30 0xc0 LINK_DISABLE

JESD204B link disable.

[31:1] RESERVED RO 0x00000000

[0] LINK_DISABLE RW 0x1

0 = Enable link, 1 = Disable link.

0x31 0xc4 LINK_STATE

JESD204B link state.

[31:2] RESERVED RO 0x00000000

[1] EXTERNAL_RESET RO

0 = External reset de-asserted, 1 = External reset asserted.

[0] LINK_STATE RO 0x1

0 = Link enabled, 1 = Link disabled.

0x32 0xc8 LINK_CLK_FREQ

[31:0] LINK_CLK_FREQ ROV

Ratio of the link_clk frequency relative to the s_axi_aclk. Format is 16.16.

0x33 0xcc DEVICE_CLK_FREQ

[20:0] DEVICE_CLK_FREQ ROV

Ratio of the device_clk frequency relative to the s_axi_aclk. Format is 16.16. Available starting from version 1.06.a;

0x40 0x100 SYSREF_CONF

SYSREF configuration

[31:2] RESERVED RO 0x00000000

[1] SYSREF_ONESHOT RW 0x0

In oneshot mode only the first occurrence of the SYSREF signal is used for alignment.

[0] SYSREF_DISABLE RW 0x0

Enable/Disable SYSREF handling.

0x41 0x104 SYSREF_LMFC_OFFSET

SYSREF LMFC offset

[31:10] RESERVED RO 0x000000

[9:0] SYSREF_LMFC_OFFSET RW 0x000

Offset between SYSREF event and internal LMFC event in octets.

0x42 0x108 SYSREF_STATUS

SYSREF status

[31:2] RESERVED RO 0x00000000

[1] SYSREF_ALIGNMENT_ERROR RW1CV 0x0

Indicates that an external SYSREF event has been observed that was unaligned to a previously observed event.

[0] SYSREF_DETECTED RW1CV 0x0

Indicates that an external SYSREF event has been observed.

0x80 0x200 LANES_DISABLE

Enabled/Disabled lanes.

[n] LANE_DISABLEn RW 0x0

Enable/Disable n-th lane (0 = enabled, 1 = disabled). Where n is from 0 to 31.

0x84 0x210 LINK_CONF0

JESD204B link configuration.

[31:19] RESERVED RO 0x0000

[18:16] OCTETS_PER_FRAME RW 0x0

Number of octets per frame - 1 (F).

[15:10] RESERVED RO 0x00

[9:0] OCTETS_PER_MULTIFRAME RW 0x003

Number of octets per multi-frame - 1 (K x F). In 64B/66B mode represents the number of octets per extended multiblock.

0x85 0x214 LINK_CONF1

JESD204B link configuration.

[31:2] RESERVED RO 0x00000000

[1] CHAR_REPLACEMENT_DISABLE RW 0x0

Enable/Disable user data alignment character replacement (0 = enabled, 1 = disabled). Valid for 8B/10B link.

[0] SCRAMBLER_DISABLE RW 0x0

Enable/Disable user data descrambling (0 = enabled, 1 = disabled).

0x86 0x218 MULTI_LINK_DISABLE

Enable/Disable links in case of a multi-link architecture. Valid for 8B/10B link.

[n] LINK_DISABLEn RW 0x0

Enable/Disable n-th link (0 = enabled, 1 = disabled). Where n is from 0 to 31.

0x87 0x21c LINK_CONF4

JESD204B link configuration.

[31:8] RESERVED RO 0x000000

[7:0] TPL_BEATS_PER_MULTIFRAME RW 0x00

Number of beats per multi-frame - 1 (K x F / TPL_DATA_PATH_WIDTH) at interface to Transport Layer. In 64B/66B mode represents the number of octets per extended multiblock. Available starting from version 1.06.a;

0x90 0x240 LINK_CONF2

JESD204B link configuration. Valid for 8B/10B link.

[31:3] RESERVED RO 0x00000000

[2] SKIP_ILAS RW 0x0

Skip ILAS sequence during link startup.

[1] CONTINUOUS_ILAS RW 0x0

Continuously transmit ILAS sequence.

[0] CONTINUOUS_CGS RW 0x0

Continuously transmit CGS sequence.

0x91 0x244 LINK_CONF3

JESD204B link configuration. Valid for 8B/10B link.

[31:8] RESERVED RO 0x000000

[7:0] MFRAMES_PER_ILAS RW 0x03

Number of multi-frames in the ILAS sequence - 1.

0x92 0x248 MANUAL_SYNC_REQUEST

Manual synchronization request. Valid for 8B/10B link.

[31:1] RESERVED RO 0x00000000

[0] MANUAL_SYNC_REQUEST W1S 0x0

Trigger manual synchronization request.

0xa0 0x280 LINK_STATUS

JESD204B link status.

[31:12] RESERVED RO 0x00000

[11:4] STATUS_SYNC ROV

Raw state of the external SYNC~ signals. Valid for 8B/10B link.

[3:2] RESERVED RO 0x0

[1:0] STATUS_STATE ROV 0x0

State of the 8B/10B link state machine. (0 = WAIT, 1 = CGS, 2 = ILAS, 3 = DATA); State of the 64B/66B link state machine. (0 = RESET, 3 = DATA)

0xc4 + 0x8*n 0x310 + 0x20*n LANEn_ILAS0

ILAS config data for the n-th lane. Valid for 8B/10B link. Where n is from 0 to 31.

[31:28] RESERVED RO 0x0

[27:24] BID RW 0x0

BID (Bank ID) field of the ILAS config sequence.

[23:16] DID RW 0x00

DID (Device ID) field of the ILAS config sequence.

[15:0] RESERVED RO 0x0000

0xc5 + 0x8*n 0x314 + 0x20*n LANEn_ILAS1

ILAS config data for the n-th lane. Valid for 8B/10B link. Where n is from 0 to 31.

[31:29] RESERVED RO 0x0

[28:24] K RW 0x00

K (Frames per multi-frame) field of the ILAS config sequence - 1.

[23:16] F RW 0x00

F (Octets per frame) field of the ILAS config sequence - 1.

[15] SCR RW 0x0

SCR (Scrambling enabled) field of the ILAS config sequence.

[14:13] RESERVED RO 0x0

[12:8] L RW 0x00

L (Number of lanes) field of the ILAS config sequence - 1.

[7:5] RESERVED RO 0x0

[4:0] LID RW 0x00

LID (Lane ID) field of the ILAS config sequence.

0xc6 + 0x8*n 0x318 + 0x20*n LANEn_ILAS2

ILAS config data for the n-th lane. Valid for 8B/10B link. Where n is from 0 to 31.

[31:29] JESDV RW 0x0

JESDV (JESD204 version) field of the ILAS config sequence.

[28:24] S RW 0x00

S (Samples per frame) field of the ILAS config sequence - 1.

[23:21] SUBCLASSV RW 0x0

SUBCLASSV (JESD204B subclass) field of the ILAS config sequence.

[20:16] NP RW 0x00

N’ (Total number of bits per sample) field of the ILAS config sequence - 1.

[15:14] CS RW 0x0

CS (Control bits per sample) field of the ILAS config sequence.

[13] RESERVED RO 0x0

[12:8] N RW 0x00

N (Converter resolution) field of the ILAS config sequence - 1.

[7:0] M RW 0x00

M (Number of converters) field of the ILAS config sequence - 1.

0xc7 + 0x8*n 0x31c + 0x20*n LANEn_ILAS3

ILAS config data for the n-th lane. Valid for 8B/10B link. Where n is from 0 to 31.

[31:24] FCHK RW 0x00

FCHK (Checksum) field of the ILAS config sequence.

[23:8] RESERVED RO 0x0000

[7] HD RW 0x0

HD (High-density) field of the ILAS config sequence.

[6:5] RESERVED RO 0x0

[4:0] CF RO 0x00

CF (control words per frame) field of the ILAS config sequence

Theory of Operation

The JESD204B/C transmit peripheral consists of two main components: the register map and the link processor.

Both components are fully asynchronous and are clocked by independent clocks. The register map is in the s_axi_aclk clock domain, while the link processor is in the clk and device_clk clock domain.

The register map is used to configure the operational parameters of the link processor as well as to query the current state of the link processor.

The link processor itself is responsible for handling the JESD204 link layer protocol.

Interfaces and Signals

Register Map Configuration Interface

The register map configuration interface can be accessed through the AXI4-Lite S_AXI interface. The interface is synchronous to the s_axi_aclk. The s_axi_aresetn signal is used to reset the peripheral and should be asserted during system startup until the s_axi_aclk is active and stable. De-assertion of the reset signal should by synchronous to s_axi_aclk.

JESD204B Control Signals

The sync and sysref signals corresponds to the SYNC~ and SYSREF signals of the JESD204 specification. These are signals generated externally and need to be connected to the peripheral for correct operation.

In 8B/10B link layer the sysref signal is optional and only required to achieve deterministic latency in subclass 1 mode operation. If the sysref signal is not connected software needs to configure the peripheral accordingly to indicate this. In 64B/66B link layer the sysref signal is mandatory.

When the sysref signal is used, in order to ensure correct operation, it is important that setup and hold of the external signal relative to the device_clk signal are met. Otherwise deterministic latency can not be guaranteed.

Transceiver Interface (TX_PHYn)

For each lane the peripheral has one corresponding TX_PHY interface. These interfaces provide the pre-processed physical layer data. The TX_PHY interfaces should be connected to the down-stream physical layer transceiver peripheral.

The physical layer peripheral receiving data from these interfaces are responsible for performing the final 8b10b mapping as well as serializing the data and transmitting it on the physical CML differential high-speed serial lane.

User Data Interface (TX_DATA)

User data is accepted on the the AXI4-Stream TX_DATA interface. The interface is a reduced AXI4-Stream interface and only features the TREADY flow control signal, but not the TVALID flow control signal. The behavior of the interface is as if the TVALID signal was always asserted. This means as soon as tx_ready is asserted a continuous stream of user data must be provided on tx_data.

../../../_images/wavedrom-14.svg

After reset and during link initialization the tx_ready signal is de-asserted. As soon as the User Data Phase is entered the tx_ready will be asserted to indicate that the peripheral is now accepting and processing the data from the tx_data signal. The tx_ready signal stays asserted until the link is either deactivated or re-initialized.

JESD204B/C Tx link layer octets mapping

Typically the TX_DATA interface is connected to a JESD204B transport layer peripheral that provides framed and lane mapped data. The internal data path width of the peripheral is four, this means that four octets per lane are processed in parallel. When in the user data phase the peripheral expects to receive data for four octets for each lane in each beat.

This means that TX_DATA interface is DATA_PATH_WIDTH * 8 * NUM_LANES bits wide. With each block of consecutive DATA_PATH_WIDTH * 8 bits corresponding to one lane. The lowest DATA_PATH_WIDTH * 8 bits correspond to the first lane, while the highest DATA_PATH_WIDTH * 8 bits correspond to the last lane. E.g. for 8B/10B mode where DATA_PATH_WIDTH=4. Each lane specific 32-bit block corresponds to four octets each 8 bits wide. The temporal ordering of the octets is from LSB to MSB, this means the octet placed in the lowest 8 bits is transmitted first, the octet placed in the highest 8 bits is transmitted last.

Data corresponding to lanes that have been disabled are ignored and their value is don’t care.

Configuration Interface

The peripheral features a register map configuration interface that can be accessed through the AXI4-Lite S_AXI port. The register map can be used to configure the peripherals operational parameters, query the current status of the device and query the features supported by the device.

Peripheral Identification and HDL Synthesis Settings

The peripheral contains multiple registers that allow the identification of the peripheral as well as the discovery of features that were configured at HDL synthesis time. Apart from the SCRATCH register all registers in this section are read-only and write to them will be ignored.

The VERSION (0x000) register contains the version of the peripheral. The version determines the register map layout and general features supported by the peripheral. The version number follows semantic versioning. Increments in the major number indicate backward incompatible changes, increments in the minor number indicate backward compatible changes, patch letter increments indicate a bug fix.

The PERIPHERAL_ID (0x004) register contains the value of the ID HDL configuration parameter that was set during synthesis. Its primary function is to allow to distinguish between multiple instances of the peripheral in the same design.

The SCRATCH (0x008) register is a general purpose 32-bit register that can be set to an arbitrary values. Reading the register will yield the value previously written (The value will be cleared when the peripheral is reset). Its content does not affect the operation of the peripheral. It can be used by software to test whether the register map is accessible or store custom peripheral associated data.

The IDENTIFICATION (0x00c) register contains the value of "204T". This value is unique to this type of peripheral and can be used to ensure that the peripheral exists at the expected location in the memory mapped IO register space.

The SYNTH_NUM_LANES (0x010) register contains the value of the NUM_LANES HDL configuration parameter that was set during synthesis. It corresponds to the maximum of lanes supported by the peripheral. Possible values are between 1 and 32.

The SYNTH_DATA_PATH_WIDTH (0x014) register contains the value of the internal data path width per lane in octets. This is how many octets are processed in parallel on each lane and affects the restrictions of possible values for certain runtime configuration registers. The value is encoded as the log2() of the data path width. Possible values are:

  1. Internal data path width is 2;

  2. Internal data path width is 4;

  3. Internal data path width is 8.

Interrupt Handling

Interrupt processing is handled by three closely related registers. All three registers follow the same layout, each bit in the register corresponds to one particular interrupt.

When an interrupt event occurs it is recorded in the IRQ_SOURCE (0x088) register. For a recorded interrupt event the corresponding bit is set to 1. If an interrupt event occurs while the bit is already set to 1 it will stay set to 1.

The IRQ_ENABLE (0x080) register controls how recorded interrupt events propagate. An interrupt is considered to be enabled if the corresponding bit in the IRQ_ENABLE register is set to 1, it is considered to be disabled if the bit is set to 0.

Disabling an interrupt will not prevent it from being recorded, but only its propagation. This means if an interrupt event was previously recorded while the interrupt was disabled and the interrupt is being enabled the interrupt event will then propagate.

An interrupt event that has been recorded and is enabled propagates to the IRQ_PENDING (0x084) register. The corresponding bit for such an interrupt will read as 1. Disabled or interrupts for which no events have been recorded will read as 0. Also if at least one interrupt has been recorded and is enabled the external irq signal will be asserted to signal the IRQ event to the upstream IRQ controller.

A recorded interrupt event can be cleared (or acknowledged) by writing a 1 to the corresponding bit to either the IRQ_SOURCE or IRQ_PENDING register. It is possible to clear multiple interrupt events at the same time by setting multiple bits in a single write operation.

For more details regarding interrupt operation see the interrupts section of this document.

Link Control

The LINK_DISABLE (0x0c0) register is used to control the link state and switch between enabled and disabled. While the link is disabled its state machine will remain in reset and it will not react to any external event like the SYSREF or SYNC~ signals.

Writing a 0 to the LINK_DISABLE register will enable the link. While the link state is changing from disabled to enabled it will go through a short initialization procedure, which will take a few clock cycles. To check whether the initialization procedure has completed and the link is fully operational the LINK_STATE (0x0c4) register can be checked. This register will contain a 0 when the link is fully enabled and will contain a 1 while it is disabled or going through the initialization procedure.

Writing a 1 to the LINK_DISABLE register will immediately disable the link.

The EXTERNAL_RESET ([1]) bit in the LINK_STATE register indicates whether the external link reset signal is asserted (1) or de-asserted (0). When the external link reset is asserted the link is disabled regardless of the setting of LINK_DISABLE. The external link reset is controlled by the fabric and might be asserted if the link clock is not stable yet.

Multi-link Control

A multi-link is a link where multiple converter devices are connected to a single logic device (FPGA). All links involved in a multi-link are synchronous and established at the same time. For an 8B/10B TX link, this means that the FPGA receives multiple SYNC signals, one for each link.

For a 8B/10B link the MULTI_LINK_DISABLE register allows activating or deactivating each SYNC~ lines independently. This is useful when depending on the use case profile some converter devices are supposed to be disabled.

Link Configuration

The link configuration registers control certain aspects of the runtime behavior of the peripheral. Since the JESD204 standard does now allow changes to link configuration while the link is active the link configuration registers can only be modified while the link is disabled. As soon as it is enabled the configuration registers turn read-only and any writes to them will be ignored.

The LANES_DISABLE (0x200) register allows to disable individual lanes. Each bit in the register corresponds to a particular lane and indicates whether that lane is enabled or disabled. Bit 0 corresponds to the first lane, bit 1 to the second lane and so on. A value of 0 for a specific bit means the corresponding lane is enabled, a value of 1 means the lane is disabled. A disabled lane will not transmit any data when the link is otherwise active. By default, all lanes are enabled.

The LINK_CONF0 register configures the octets-per-frame and frames-per-multi-frame settings of the link. The OCTETS_PER_FRAME ([18:16]) field should be set to the number of octets-per-frame minus 1 (F - 1). The OCTETS_PER_MULTIFRAME ([9:0]) field should be set to the number of octets-per-frame multiplied by the number of frames-per-multi-frame minus 1 (FxK - 1). For correct operation FxK must be a multiple of DATA_PATH_WIDTH. In 64B/66B mode this field matches and also represents the number of octets per extended multiblock (Ex32x8 - 1).

The LINK_CONF1 register controls the optional link level processing stages. The SCRAMBLER_DISABLE ([0]) bit controls whether scrambling of the transmitted user data is enabled or disabled. A value of 0 enables scrambling and a value of 1 disables it. In 64B/66B mode scrambling must be always enabled. The CHAR_REPLACEMENT_DISABLE ([1]) bit controls whether alignment character replacement is performed or not. A value of 0 enables character replacement and a value of 1 disables it. For correct operation, character replacement must be disabled when scrambling is disabled otherwise undefined behavior might occur.

Both the transmitter as well as receiver device on the JESD204 link need to be configured with the same settings for scrambling/descrambling and character replacement for correct operation.

It is recommended to leave both scrambling as well as alignment character replacement enabled during normal operation and only disable it for debugging or testing purposes.

Character replacement is used only in 8B/10B links and completely disregarded in 64B/66B mode.

The LINK_CONF2 (0x240) register contains configuration data that affects the transitions of the link state machine. If the CONTINUOUS_CGS ([0]) bit is set the state machine will remain in the CGS phase indefinitely and send repeated /K/ control character. If the CONTINUOUS_ILAS ([1]) bit is set the state machine will remain in the ILAS phase indefinitely and send repeated ILAS sequences. If the SKIP_ILAS ([2]) bit is set the state machine will directly transition to the DATA phase from the CGS phase without going through the ILAS phase. The LINK_CONFIG2 register is used only in 8B/10B links and completely disregarded in 64B/66B mode.

The LINK_CONF3 (0x244) register configures the duration of the ILAS sequence in number of multi-frames. Its value is equal to the number of multi-frames minus one. In the current iteration of the peripheral, this register is read-only and the ILAS will always last for four multi-frames. The LINK_CONFIG3 register is used only in 8B/10B links and completely disregarded in 64B/66B mode.

ILAS Configuration Data

For 8B/10B link layer the ILAS configuration data registers contain the configuration data that is sent during the ILAS phase. Similar to the link configuration registers, the ILAS configuration data registers can only be modified while the link is disabled and turn read-only as soon as it is enabled.

For each lane there is a set of four registers (LANEn_ILAS0, LANEn_ILAS1, LANEn_ILAS2, LANEn_ILAS3) that allow access to the 14 configuration data octets. Aside from the LID and FCHK fields all fields for each of the lanes map to the same internal storage. This means only the LID and FCHK fields can be configured with per-lane configuration data, all other fields must be set to the same value for all lanes.

SYSREF Handling

The external SYSREF signal is used to align the internal local multiframe clocks (LMFC)/ local-multiblock-clock (LEMC) between multiple devices on the same link.

The SYSREF_CONF (0x100) register controls the behavior of the SYSREF capture circuitry. Setting the SYSREF_DISABLE ([0]) bit to 1 disables the SYSREF handling. All external SYSREF events are ignored and the LMFC/LEMC is generated internally. For Subclass 1 operation SYSREF handling should be enabled and for Subclass 0 operation it should be disabled.

The SYSREF_LMFC_OFFSET (0x104) register allows modifying the offset between the SYSREF rising edge and the rising edge of the LMFC/LEMC. Must be a multiple of DATA_PATH_WIDTH.

For optimal operation, it is recommended that all device on a JESD204 link should be configured in a way so that the total offset between

The value of the SYSREF_LMFC_OFFSET register must be set to a value smaller than the configured number of octets-per-multiframe (OCTETS_PER_MULTIFRAME), otherwise undefined behavior might occur.

The SYSREF_STATUS (0x108) register allows monitoring the status of the SYSREF signals. SYSREF_DETECTED ([0]) bit indicates that the peripheral as observed a SYSREF event. The SYSREF_ALIGNMENT_ERROR ([1]) bit indicates that a SYSREF event has been observed which was unaligned, in regards to the LMFC period, to a previously recorded SYSREF event.

All bits in the SYSREF_STATUS register are write-to-clear. All bits will also be cleared when the link is disabled.

Note that the SYSREF_STATUS register will not record any events if SYSREF operation is disabled or the JESD204 link is disabled.

Link Status

All link status registers are read-only. While the link is disabled some of the link status registers might contain bogus values. Their content should be ignored until the link is fully enabled.

The STATUS_STATE ([1:0]) field of the LINK_STATUS (0x280) register indicates the state of the 8B/10B link state machine or 64B/66B link state machine depending on the selected encoder. Possible values are:

Possible values for a 8B/10B link are:

  • 0: WAIT phase;

  • 1: CGS phase;

  • 2: ILAS phase;

  • 3: DATA phase.

Possible values for a 64B/66B link are:

  • 0: WAIT phase;

  • 3: DATA phase.

The STATUS_SYNC ([4]) field represents the raw state of the external SYNC~ and can be used to monitor whether the JESD204B converter device has requested link synchronization. This is available only for 8B/10B links.

Manual Synchronization Request

For 8B/10B links the MANUAL_SYNC_REQUEST (0x248) register can be used to transition the link state from the WAIT phase to the CGS phase in the absence of an external synchronization request. This is useful for test cases where the peripheral is connected to signal analyzer instead of a JESD204B receiver device.

Writing a 1 to this register will trigger a manual synchronization request. Writing the register while the link is disabled or writing a 0 to the register has no effect. The register is self-clearing and reading it will always return 0.

This feature is useful if the SYNC~ is stuck high from some reason. Setting the MANUAL_SYNC_REQUEST bit will bring out the Tx link peripheral from CGS and will continue with sending ILAS and DATA information. After this, the SYNC_STATUS bit would read high, and LINK_STATE would be DATA.

If the SYNC~ is stuck low, writing the MANUAL_SYNC_REQUEST would not do too much, the link would stay in CGS and wait the de-assertion of SYNC~ which won’t happen. In this case the SYNC_STATUS would stay low and LINK_STATEwould be CGS.

Clock Monitor

The LINK_CLK_FREQ (0x0c8) register allows to determine the clock rate of the link clock (clk) relative to the AXI interface clock (s_axi_aclk). This can be used to verify that the link clock is running at the expected rate.

The DEVICE_CLK_FREQ (0x0cc) register allows to determine the clock rate of the device clock (device_clk) relative to the AXI interface clock (s_axi_aclk). This can be used to verify that the device clock is running at the expected rate.

The number is represented as unsigned 16.16 format. Assuming a 100MHz processor clock this corresponds to a resolution of 1.523kHz per LSB. A raw value of 0 indicates that the link clock is currently not active.

Interrupts

The core does not generate interrupts.

8B/10B Link

../../../_images/axi_jesd204_tx_204c_8b10b.svg

8B/10B Link State Machine

../../../_images/jesd204_tx_state_machine.svg

The peripheral can be in one of four main operating phases: WAIT, CGS, ILAS or DATA. Upon reset the peripheral starts in the WAIT phase. The CGS and ILAS phases are used during the initialization of the JESD204B link. The DATA phase is used during normal operation when user data is transmitted across the JESD204B link.

Wait Phase (WAIT)

The WAIT phase is the default state entered during reset. While disabled the peripheral will stay in the WAIT phase. When enabled, the peripheral will stay in the WAIT phase until a synchronization request is received.

A synchronization request can either be generated manually through the register map configuration interface or by one of the JESD204B receivers by asserting the SYNC~ signal. Once a synchronization request is received the peripheral transitions to the CGS phase.

During the WAIT phase the peripheral will continuously transmit /K/ control character on each of the TX_PHYn interfaces.

If at any point the peripheral is disabled, it will automatically transition back to the WAIT state.

Lanes that have been disabled in the register map configuration interface, will behave as if the link was in the WAIT state regardless of the actual state.

Code Group Synchronization Phase (CGS)

During the CGS phase the peripheral will continuously transmit /K/ control character on each of the TX_PHYn interfaces.

The peripheral will stay in the CGS phase until all of following conditions are satisfied:

  • The synchronization request is de-asserted;

  • The CGS phase has lasted for at least the configured minimum CGS duration (1 frame + 9 octets by default);

  • The end of a multi-frame is reached (This means the next phase will start at the beginning of a multi-frame);

  • The SYSREF signal has been captured and the LMFC is properly aligned.

If the peripheral is configured for continuous CGS operation it will stay in the CGS phase indefinitely regardless of whether the above conditions are met or not.

By default the peripheral will transition to the ILAS phase at the end of the CGS phase. If the core is configured to skip the ILAS phase it will instead directly transition to the DATA phase.

Initial Lane Alignment Sequence Phase (ILAS)

During the ILAS phase the peripheral transmits the initial lane alignment sequence. The transmitted ILAS consists of four multi-frames. The first octet of each multi-frame is the /R/ control character and the last octet of each multi-frame is the /A/ control character.

During the second multi-frame the link configuration data is transmitted from the 3rd to 16th octet. The second octet of the second multi-frame is the /Q/ control character to indicate that this multi-frame carries configuration data. The ILAS configuration data sequence can be programmed through the register map configuration interface.

All other octets of the ILAS sequence will contain the numerical value corresponding to the position of the octet in the ILAS sequence (E.g. the fifth octet of the first multi-frame contains the value 4).

../../../_images/wavedrom-24.svg

By default the ILAS is transmitted for a duration of 4 multi-frames. After the last ILAS multi-frame the peripheral switches to the DATA phase.

If the peripheral is configured for continuous ILAS operation it will instead remain in the ILAS phase indefinitely. In continuous ILAS mode the peripheral will transition back to the first multi-frame of the ILAS sequence after the last multi-frame has been transmitted.

In accordance with the JESD204B standard the data transmitted during the ILAS phase is not scrambled regardless of whether scrambling is enabled or not.

User Data Phase (DATA)

The DATA phase is the main operating mode of the peripheral. In this phase it will receive transport layer data at the TX_DATA port, split it onto the corresponding lanes and perform per-lane processing of the data according to the peripherals configuration. When the peripheral enters the DATA phase the ready signal of the TX_DATA will be asserted to indicate that transport layer data is now accepted.

By default the data transmitted on each lane will be scrambled. Scrambling can optionally be disabled via the register map configuration interface. Scrambling is enabled or disabled for all lanes equally.

Scrambling reduces data-dependent effects, which can affect both the analog performance of the data converter as well as the bit-error rate of JESD204B serial link, therefore it is highly recommended to enable scrambling.

The peripheral also performs per-lane alignment character replacement. Alignment character replacement will replace under certain predictable conditions (i.e. the receiver can recover the replaced character) the last octet in a frame or multi-frame. Replaced characters at the end of a frame, that is also the end of a multi-frame, are replaced by the /A/ character. Replaced characters at the end of a frame, that is not the end of a multi-frame, are replaced by the /F/ character. Alignment characters can be used by the receiver to ensure proper frame and lane alignment.

Alignment character replacement can optionally be disabled via the register map configuration interface. Alignment character replacement is enabled or disabled for all lanes equally. Alignment character replacement is only available when scrambling is enabled and must be disabled when scrambling is disabled, otherwise undefined behavior might occur.

Data on the TX_DATA port corresponding to a disabled lane is ignored.

8B/10B Multi-endpoint TX link establishment

In a multi-endpoint configuration one link transmit peripheral connects to several endpoints/converter devices. In such cases the link is established only when all enabled endpoints reach the DATA phase. For that all endpoints must pass through CGS and ILAS stages.

Depending on the software implementation that controls the converter devices the endpoints can be enabled at different moments. The link transmit peripheral will send CGS characters until all enabled endpoints succeeded character alignment and signalize that through the de-assertion of SYNC~ signal.

In the below example we have a multi-point link of four endpoints (NUM_LINKS = 4):

../../../_images/quadmxfe_linkbringup_204b_dac.svg

Note

The physical layer is not depicted on purpose. JRXn represents the link layer counterpart in the converter device/endpoint n.

The steps of the link bring-up are presented below:

  • 1 - Link transmit peripheral is enabled, will start to send CGS characters on all lanes regardless of the state of the SYNC~ signal;

  • 2,3,4,5 - JESD Receive block of ADC enabled, its corresponding SYNC~ pin is pulled low. The timing depends on the software implementation that controls the ADC;

  • 6 - In Subclass 1 (SC1) SYSREF is captured and LMFC in the FPGA and converter device is adjusted;

  • 7 - Once the CGS characters are received correctly, on the next Frame clock boundary in SC0 or LMFC boundary in SC1 the SYNC~ is de-asserted;

  • 8 - Once all enabled endpoints (not masked by MULTI_LINK_DISABLE) de-assert the SYNC~ signal, on the next Frame clock boundary for SC0 or the next LMFC boundary for SC1, the transmit peripheral will start sending the ILAS sequence, then MFRAMES_PER_ILAS (typically 4) LMFC periods later the actual DATA. In SC1 if SYSREF is not captured the link transmit peripheral will stay in CGS state.

Diagnostics

Troubleshooting JESD204B Tx links

64B/66B Link

../../../_images/axi_jesd204_tx_204c_64b66b.svg

The 64-bit wide datapath of the link layer is fairly simple, the only mandatory part of the 64B66B link layer datapath is the scrambler. This must be active during the operation of the link, however for debug purposes can be bypasses with a control register SCRAMBLER_DISABLE.

The data is accepted from the upstream transport layer core once the local extended multiblock clock (LEMC) is adjusted to the captured SYSREF signal. Once this happened the data will be accepted without interruption until the link is disabled since there is no back-pressure from the physical layer.

If the core does not receives at least one SYSREF pulse it will not pass any data from transport layer to physical layer.

For each multiblock sent on the data interface a CRC is calculated which is sent on the 2-bit sync header stream during the next multiblock period. Beside the CRC the sync header stream contains synchronization information to mark the boundary of the multiblock and extended multiblocks.

Dual clock operation

In case ASYNC_CLK parameter is set, a gearbox with 4:N (204B) or 8:N (204C) ratio is enabled in the link layer peripherals, where N depends on the F parameter of the link. The goal of the gearbox is to have at the transport layer interface a data width that contains an integer number of frames per every device clock cycle (each beat) so an integer number of samples can be delivered/consumed to/from the application layer aligned to SYSREF ensuring deterministic latency in modes where N’=12 or F!=1,2,4.

../../../_images/dual_clock_operation1.svg

The gearbox ratio corresponds with the ratio of the link layer interface data width towards physical layer and transport layer in octets. The interface width towards the physical layer in 8B/10B (204B) mode depends on the DATA_PATH_WIDTH synthesis parameter, and can be either 4 octets (default) or 8 octets. In 204B mode the util_adxcvr supports only data width of 4 octets. In 64b66b (aka 204C) mode the data width towards the physical interface is always 8 octets.

The data path width towards the transport layer is defined by the TPL_DATA_PATH_WIDTH synthesis parameter.

The following rules apply:

  • TPL_DATA_PATH_WIDTH >= DATA_PATH_WIDTH;

  • TPL_DATA_PATH_WIDTH = m x F; where m is a positive integer, power of 2.

The link clock and device clock ratio should be the inverse of the DATA_PATH_WIDTH : TPL_DATA_PATH_WIDTH ratio.

In this context the link clock will be lane rate/40 or lane rate/80 for 204B depending on DATA_PATH_WIDTH and lane rate / 66 for 204C 64B/66B, however the device clock could vary based in the F parameter.

Software Support

Warning

To ensure correct operation it is highly recommended to use the Analog Devices provided JESD204B software packages for interfacing the peripheral. Analog Devices is not able to provide support in case issues arise from using custom low-level software for interfacing the peripheral.

  • JESD204B Transmit Linux Driver Support

Restrictions

During the design of the peripheral the deliberate decision was made to support only a subset of the features mandated by the JESD204B standard for transmitter logic devices.

The reasoning here is that the peripheral has been designed to interface to Analog Devices JESD204B DAC converter devices and features that are either not required or not supported by those converter devices would otherwise lie dormant in peripheral and never be used.

Instead, the decision was made to not implement those unneeded features, even when the JESD204B standard requires them for general purpose JESD204B transmitter logic devices. As Analog Devices DAC converter devices with new requirements are released the peripheral will be adjusted accordingly.

This approach allows for a leaner design using less resources, allowing for lower pipeline latency and a higher maximum device clock frequency.

The following lists where the peripheral deviates from the standard:

  • No subclass 2 support. JESD204B subclass 2 has, due to its implementation details, restricted applicability and is seldom a viable option for a modern high-speed data converter system. To achieve deterministic latency it is recommend to use subclass 1 mode;

  • Reduced number of octets-per-frame settings. The JESD204B standard allows for any value between 1 and 256 to be used for the number of octets-per-frame;

  • The following octets-per-frame values are supported by the peripheral: 1, 2, 4 and 8 (no longer applies starting from 1.06.a);

  • Reduced number of frames-per-multi-frame settings. The following values are supported by the peripheral: 1-32, with the additional requirement that F*K is a multiple of 4. In addition F*K needs to be in the range of 4-256;

  • No support for alignment character replacement when scrambling is disabled (no longer applies starting from 1.06.a).

Supported Devices

JESD204B Digital-to-Analog Converters

  • AD9135: Dual, 11-Bit, high dynamic, 2.8 GSPS, TxDAC+ Digital-to-Analog Converter

  • AD9136: Dual, 16-Bit, 2.8 GSPS, TxDAC+ Digital-to-Analog Converter

  • AD9144: Quad, 16-Bit, 2.8 GSPS, TxDAC+ Digital-to-Analog Converter

  • AD9152: Dual, 16-Bit, 2.25 GSPS, TxDAC+ Digital-to-Analog Converter

  • AD9154: Quad, 16-Bit, 2.4 GSPS, TxDAC+ Digital-to-Analog Converter

  • AD9161: 11-Bit, 12 GSPS, RF Digital-to-Analog Converter

  • AD9162: 16-Bit, 12 GSPS, RF Digital-to-Analog Converter

  • AD9163: 16-Bit, 12 GSPS, RF DAC and Digital Upconverter

  • AD9164: 16-Bit, 12 GSPS, RF DAC and Direct Digital Synthesizer

  • AD9172: Dual, 16-Bit, 12.6 GSPS RF DAC with Channelizers

  • AD9173: Dual, 16-Bit, 12.6 GSPS RF DAC with Channelizers

  • AD9174: Dual, 16-Bit, 12.6 GSPS RF DAC and Direct Digital Synthesizer

  • AD9175: Dual, 11-Bit/16-Bit, 12.6 GSPS RF DAC with Wideband Channelizers

  • AD9176: Dual, 16-Bit, 12.6 GSPS RF DAC with Wideband Channelizers

  • AD9177: Quad, 16-Bit, 12 GSPS RF DAC with Wideband Channelizers

JESD204B RF Transceivers

  • AD9371: SDR Integrated, Dual RF Transceiver with Observation Path

  • AD9375: SDR Integrated, Dual RF Transceiver with Observation Path and DPD

  • ADRV9009: SDR Integrated, Dual RF Transceiver with Observation Path

  • ADRV9008-1: SDR Integrated, Dual RF Receiver

  • ADRV9008-2: SDR Integrated, Dual RF Transmitter with Observation Path

JESD204B/C Mixed-Signal Front Ends

  • AD9081: MxFE Quad, 16-Bit, 12GSPS RFDAC and Quad, 12-Bit, 4GSPS RFADC

  • AD9082: MxFE QUAD, 16-Bit, 12GSPS RFDAC and DUAL, 12-Bit, 6GSPS RFADC

  • AD9986: 4T2R Direct RF Transmitter and Observation Receiver

  • AD9988: 4T4R Direct RF Receiver and Transmitter

Technical Support

Analog Devices will provide limited online support for anyone using the core with Analog Devices components (ADC, DAC, Clock, etc) via the EngineerZone under the GPL license. If you would like deterministic support when using this core with an ADI component, please investigate a commercial license. Using a non-ADI JESD204 device with this core is possible under the GPL, but Analog Devices will not help with issues you may encounter.

More Information

  • JESD204B High-Speed Serial Interface Support

  • Troubleshooting JESD204B TX links

  • HDL User Guide

  Generic JESD204 block designs JESD204B/C Link Receive Peripheral
©2024, Analog Devices, Inc. | Made with Sphinx & Doctools