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White Rabbit

Calibration

Last edited by Grzegorz Daniluk
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White Rabbit devices calibration

This page is meant to provide coarse calibration values for the official releases of
WR Switch and WR PTP Core firmware. You can use them as defaults for matching
hardware and gateware version. However, to achieve the best possible synchronization
results you should perform the full calibration procedure for your
WR hardware.

Short introduction about the calibration problem

White Rabbit link established between two devices is characterized with hardware delays
and fiber propagation latencies presented in figure 1.


Figure1: White Rabbit link delay model*

Each WR Master and WR Slave has some constant transmission and reception delays:

  • Δ TXM - transmission delay of WR Master
  • Δ RXM - reception delay of WR Master
  • Δ TXS - transmission delay of WR Slave
  • Δ RXS - reception delay of WR Slave

They are the summed result of SFP transceiver’s, PCB traces’ and electronic components’
delays as well as the delays inside FPGA chip. Additional reception delay is also caused
on both sides by aligning recovered clock signal to the inter-symbol boundaries of data
stream. It is called bitslide value and is marked in figure 1 as:

  • ε M - bitslide of Master's RX path
  • ε S - bitslide of Slave's RX path

Except from hardware delays, packets transmitted in fiber are affected with propagation
latencies in both directions:

  • δ MS - Master-to-Slave fiber latency
  • δ SM - Slave-to-Master fiber latency

Those fiber propagation latencies are not equal since different light wavelengths are used
to communicate simultaneously in both directions using single fiber (Wavelength Division
Multiplexing). For estimating fiber asymmetry White Rabbit uses α parameter, which
is constant for given wavelengths and type of fiber.

WR users should perform the WR Calibration Procedure before deploying WR
hardware to determine correct values of delays and fiber asymmetry factor.

Default calibration values for WR Switch

Below you can find the default calibration values for latest stable releases of the WR Switch.
You should put these values in the dot-config file. Depending on your configuration, you
should either edit the /wr/etc/dot-config file on your switch, or modify it on the central
server, from which the WRS fetches dot-config on boot time. The former requires accessing
the WRS shell either by using the USB-UART management port in the front panel or SSH-ing
through the management Ethernet port. You can edit /wr/etc/dot-config using vi editor.
Please use appropriate values depending on your hardware and firmware version. However, bear
in mind that these numbers are valid only for release binaries you can download from the
ohwr.org. If you re-synthesize the gateware, you have to perform the calibration procedure
to find the new values.

Firmware v5.0 / Hardware v3.4 (7Solutions and Creotech) 

#
# Port Timing Configuration
#
CONFIG_PORT01_PARAMS="name=wri1,proto=raw,tx=223897,rx=226273,role=slave,fiber=0"
CONFIG_PORT02_PARAMS="name=wri2,proto=raw,tx=224037,rx=226377,role=master,fiber=0"
CONFIG_PORT03_PARAMS="name=wri3,proto=raw,tx=224142,rx=226638,role=master,fiber=0"
CONFIG_PORT04_PARAMS="name=wri4,proto=raw,tx=224313,rx=226471,role=master,fiber=0"
CONFIG_PORT05_PARAMS="name=wri5,proto=raw,tx=224455,rx=227679,role=master,fiber=0"
CONFIG_PORT06_PARAMS="name=wri6,proto=raw,tx=224603,rx=227891,role=master,fiber=0"
CONFIG_PORT07_PARAMS="name=wri7,proto=raw,tx=224761,rx=228055,role=master,fiber=0"
CONFIG_PORT08_PARAMS="name=wri8,proto=raw,tx=224898,rx=228178,role=master,fiber=0"
CONFIG_PORT09_PARAMS="name=wri9,proto=raw,tx=225069,rx=228277,role=master,fiber=0"
CONFIG_PORT10_PARAMS="name=wri10,proto=raw,tx=225245,rx=228435,role=master,fiber=0"
CONFIG_PORT11_PARAMS="name=wri11,proto=raw,tx=225463,rx=228963,role=master,fiber=0"
CONFIG_PORT12_PARAMS="name=wri12,proto=raw,tx=225645,rx=229107,role=master,fiber=0"
CONFIG_PORT13_PARAMS="name=wri13,proto=raw,tx=225801,rx=229225,role=master,fiber=0"
CONFIG_PORT14_PARAMS="name=wri14,proto=raw,tx=225983,rx=229463,role=master,fiber=0"
CONFIG_PORT15_PARAMS="name=wri15,proto=raw,tx=226208,rx=229850,role=master,fiber=0"
CONFIG_PORT16_PARAMS="name=wri16,proto=raw,tx=226393,rx=229907,role=master,fiber=0"
CONFIG_PORT17_PARAMS="name=wri17,proto=raw,tx=226594,rx=230106,role=master,fiber=0"
CONFIG_PORT18_PARAMS="name=wri18,proto=raw,tx=226737,rx=230273,role=master,fiber=0"

#
# SFP and Media Timing Configuration
#
CONFIG_SFP00_PARAMS="vn=Axcen Photonics,pn=AXGE-1254-0531,tx=0,rx=0,wl_txrx=1310+1490"
CONFIG_SFP01_PARAMS="vn=Axcen Photonics,pn=AXGE-3454-0531,tx=0,rx=0,wl_txrx=1490+1310"
CONFIG_SFP02_PARAMS="vn=APAC Opto,pn=LS38-C3S-TC-N-B9,tx=761,rx=557,wl_txrx=1310+1490"
CONFIG_SFP03_PARAMS="vn=APAC Opto,pn=LS48-C3S-TC-N-B4,tx=-29,rx=507,wl_txrx=1490+1310"
CONFIG_FIBER00_PARAMS="alpha_1310_1490=2.6787e-04"

Firmware v5.0 / Hardware v3.3 (7Solutions) 

#
# Port Timing Configuration
#
CONFIG_PORT01_PARAMS="name=wri1,proto=raw,tx=224295,rx=225959,role=slave,fiber=0"
CONFIG_PORT02_PARAMS="name=wri2,proto=raw,tx=224500,rx=226090,role=master,fiber=0"
CONFIG_PORT03_PARAMS="name=wri3,proto=raw,tx=224642,rx=226250,role=master,fiber=0"
CONFIG_PORT04_PARAMS="name=wri4,proto=raw,tx=224763,rx=226197,role=master,fiber=0"
CONFIG_PORT05_PARAMS="name=wri5,proto=raw,tx=224879,rx=227321,role=master,fiber=0"
CONFIG_PORT06_PARAMS="name=wri6,proto=raw,tx=225021,rx=227509,role=master,fiber=0"
CONFIG_PORT07_PARAMS="name=wri7,proto=raw,tx=225215,rx=227743,role=master,fiber=0"
CONFIG_PORT08_PARAMS="name=wri8,proto=raw,tx=225355,rx=227833,role=master,fiber=0"
CONFIG_PORT09_PARAMS="name=wri9,proto=raw,tx=225487,rx=227993,role=master,fiber=0"
CONFIG_PORT10_PARAMS="name=wri10,proto=raw,tx=225682,rx=228104,role=master,fiber=0"
CONFIG_PORT11_PARAMS="name=wri11,proto=raw,tx=225968,rx=228600,role=master,fiber=0"
CONFIG_PORT12_PARAMS="name=wri12,proto=raw,tx=226137,rx=228733,role=master,fiber=0"
CONFIG_PORT13_PARAMS="name=wri13,proto=raw,tx=226259,rx=228899,role=master,fiber=0"
CONFIG_PORT14_PARAMS="name=wri14,proto=raw,tx=226426,rx=229102,role=master,fiber=0"
CONFIG_PORT15_PARAMS="name=wri15,proto=raw,tx=226740,rx=229506,role=master,fiber=0"
CONFIG_PORT16_PARAMS="name=wri16,proto=raw,tx=226882,rx=229594,role=master,fiber=0"
CONFIG_PORT17_PARAMS="name=wri17,proto=raw,tx=227016,rx=229740,role=master,fiber=0"
CONFIG_PORT18_PARAMS="name=wri18,proto=raw,tx=227248,rx=229932,role=master,fiber=0"

#
# SFP and Media Timing Configuration
#
CONFIG_SFP00_PARAMS="vn=Axcen Photonics,pn=AXGE-1254-0531,tx=0,rx=0,wl_txrx=1310+1490"
CONFIG_SFP01_PARAMS="vn=Axcen Photonics,pn=AXGE-3454-0531,tx=0,rx=0,wl_txrx=1490+1310"
CONFIG_SFP02_PARAMS="vn=APAC Opto,pn=LS38-C3S-TC-N-B9,tx=761,rx=557,wl_txrx=1310+1490"
CONFIG_SFP03_PARAMS="vn=APAC Opto,pn=LS48-C3S-TC-N-B4,tx=-29,rx=507,wl_txrx=1490+1310"
CONFIG_FIBER00_PARAMS="alpha_1310_1490=2.6787e-04"

If the version you are looking for is not on the least above, please check the default calibration values for old firmware releases.

Default calibration values for White Rabbit PTP Core running on SPEC board

WR PTP Core stores Δ TX, Δ RX and α values in SFP database stored in EEPROM.
To deploy calibration values from table below you have to access WRPC Shell through USB-UART or
VUART (please check the latest WRPC release manual for more information).
First thing to do is clearing existing SFP database:

wrc# sfp erase

Then you can add each SFP with its parameters using sfp add shell command:

wrc# sfp add <SFP part number> <deltaTx> <deltaRx> <alpha>

SFP database for SPEC

The values from the table below can be used with official release binary of WRPC reference design.

WRPC version HW board SFP Δ TX Δ RX α wrc# cmd;
v4.2 SPEC AXGE-1254-0531 180750 148326 72169888 sfp add AXGE-1254-0531 180750 148326 72169888
v4.2 SPEC AXGE-3454-0531 180750 148326 -73685416 sfp add AXGE-3454-0531 180750 148326 -73685416
v4.2 SVEC AXGE-1254-0531 178377 152463 72169888 sfp add AXGE-1254-0531 178377 152463 72169888
v4.2 SVEC AXGE-3454-0531 178377 152463 -73685416 sfp add AXGE-3454-0531 178377 152463 -73685416
v4.2 VFC-HD AXGE-1254-0531 188147 -8681 72169888 sfp add AXGE-1254-0531 188147 -8681 72169888
v4.2 VFC-HD AXGE-3454-0531 188147 -8681 -73685416 sfp add AXGE-3454-0531 188147 -8681 -73685416
v4.1 SPEC v4 AXGE-1254-0531 180774 148774 72169888 sfp add AXGE-1254-0531 180774 148774 72169888
v4.1 SPEC v4 AXGE-3454-0531 180774 148774 -73685416 sfp add AXGE-3454-0531 180774 148774 -73685416
v4.1 SVEC AXGE-1254-0531 176073 149565 72169888 sfp add AXGE-1254-0531 176073 149565 72169888
v4.1 SVEC AXGE-3454-0531 176073 149565 -73685416 sfp add AXGE-3454-0531 176073 149565 -73685416
v4.1 VFC-HD AXGE-1254-0531 189555 -7407 72169888 sfp add AXGE-1254-0531 189555 -7407 72169888
v4.1 VFC-HD AXGE-3454-0531 189555 -7407 -73685416 sfp add AXGE-3454-0531 189555 -7407 -73685416
v4.0 SPEC v4 AXGE-1254-0531 180667 148735 72169888 sfp add AXGE-1254-0531 180667 148735 72169888
v4.0 SPEC v4 AXGE-3454-0531 180667 148735 -73685416 sfp add AXGE-3454-0531 180667 148735 -73685416
v4.0 SVEC AXGE-1254-0531 178446 152666 72169888 sfp add AXGE-1254-0531 178446 152666 72169888
v4.0 SVEC AXGE-3454-0531 178446 152666 -73685416 sfp add AXGE-3454-0531 178446 152666 -73685416
v4.0 VFC-HD AXGE-1254-0531 187792 -8140 72169888 sfp add AXGE-1254-0531 187792 -8140 72169888
v4.0 VFC-HD AXGE-3454-0531 187792 -8140 -73685416 sfp add AXGE-3454-0531 187792 -8140 -73685416
v3.0 SPEC v4 AXGE-1254-0531 180625 148451 72169888 sfp add AXGE-1254-0531 180625 148451 72169888
v3.0 SPEC v4 AXGE-3454-0531 180625 148451 -73685416 sfp add AXGE-3454-0531 180625 148451 -73685416
v2.1 SPEC v4 AXGE-1254-0531 180707 148323 72169888 sfp add AXGE-1254-0531 180707 148323 72169888
v2.1 SPEC v4 AXGE-3454-0531 180707 148323 -73685416 sfp add AXGE-3454-0531 180707 148323 -73685416

If you are using the wr-nic release (included in the WR Starting Kit) please use the value in the table below:

FW version HW board SFP Δ TX Δ RX α wrc# cmd;
wr-nic-v2.0 SPEC v4 AXGE-1254-0531 177648 150988 68930293 sfp add AXGE-1254-0531 177648 150988 68930293
wr-nic-v2.0 SPEC v4 AXGE-3454-0531 181210 154818 -66901714 sfp add AXGE-3454-0531 181210 154818 -66901714

18 December 2017, Grzegorz Daniluk, Benoit Rat

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