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sabrina
Newbie
Newbie
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Registered: ‎02-08-2021

Using the same gtx for aurora 64b/66b transmission and 8b/10b reception

Hello,

I am trying to use the same GTX with a different configuration for the TX and the RX. The FPGA device is: xc7vx485tffg1157-2 and I am using the IP core version v3.6 for the 7 series FPGAs Transceivers Wizard

Both the TX and the RX share the same reference clock and work at the same line rate.

The configuration for the TX is the following one:

Line rate :6.4Gbps

refclk:160MHz

PLL selection: QPLL

clock source: refclk1 Q1

--Encoding:

ext data width: 64 bits

encoding: 64b/66b with ext seq ctrl

Internal data width: 32 bits


The configuration for the RX is the following one:

Line rate :6.4Gbps;

refclk: 160MHz

PLL selection: QPLL

clock source: refclk1 Q1

--Encoding:

ext data width:16 bits

encoding: 8b/10b

Internal data width: 20 bits

When I tried to simulate the behavior of the RX, it wasn't correctly working. Then looking into the configuration of the GTXE2_CHANNEL primitive, I noticed the RX gearbox was enabled, and I wasn't able to change this setting from the wizard. I also noticed that if I set the encoding scheme of the TX to NONE, the configuration of the RX is affected, and in particular, the RX gearbox is disabled, as I would expect.

I thought that there could be a bug in the IP core... Then, I imported the source files from the gt IP and edited the two lines regarding the RX gearbox attributes.

The original settings were:

-------------------------RX Gearbox Attributes---------------------------
RXGEARBOX_EN => ("TRUE"),
GEARBOX_MODE => ("001"),

and the values I manually set were:

-------------------------RX Gearbox Attributes---------------------------
RXGEARBOX_EN => ("FALSE"),
GEARBOX_MODE => ("000"),

With these new settings, the simulation was successful.

Then could you confirm that there is a bug, or could you help me in understanding why the project is not working using the original files automatically generated with the wizard?

Thank you,

Sabrina

 

 

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