E-Tile XCVR PHY Gearbox 64/66 mode

[LNagy2]

Hello community, 

I would be interested on more details on the "Gearbox 64/66" mode of the E-Tile XCVR PHY IP

https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/ug/ug_etile_xcvr_phy.pdf

1. How is the 80 bits  parallel data interface mapped in this mode ? 

2. "You must use data_valid signals on both the TX and RX directions."     Where are these data_valid  signals mapped on the interface of the core ?

3. It is possible to use the PHY in a 66 ratio serdes mode, meaning we feed 66 bits at the parallel data interface on each clock cycle while using the div66 clock option to drive the core interface?  See attached screenshot.

I would like to use NRZ mode with lane rates <25Gbps.

Thank you,

Laszlo

[Deshi_Intel]

HI,

Pls see my reply below.

1. How is the 80 bits parallel data interface mapped in this mode ? 

• Kindly refer to mapping table (Table 33. 80 Bit Data Native PHY IP Double-width TX/RX Ports, page 63)

2. "You must use data_valid signals on both the TX and RX directions."   Where are these data_valid signals mapped on the interface of the core ?

• valid signal = parallel_data[68]

3. It is possible to use the PHY in a 66 ratio serdes mode, meaning we feed 66 bits at the parallel data interface on each clock cycle while using the div66 clock option to drive the core interface? See attached screenshot.

• Yes. in NativePHY IP, you need to first checked "enable tx pma div66 clock" and "enable rx pma div66 clock" in TX PMA and Rx PMA tab
• Then in NativePHY IP -> core interface tab, Tx clocks option and Rx clock option
• Enable clkout2 port and set the clock source to div66

Thanks.

Regards,

dlim

[LNagy2]

Hello dlim, 

thanks for the quick reply.   I had to set also the tx_clkout/rx_clkout  to half-rate. 

With this setup I got a parallel data interface running at lane rate / 64 , that means I need to deassert valid each 33th cycle. 

Is there a setup where I can have a parallel interface running at lane rate/66 meaning the 'valid' can stay high all the time ? 

Thank you,

Laszlo

[Deshi_Intel]

Hi Laszlo,

Sorry for the late reply.

The parameter setting that you are interested with is called "PMA width" setting in "PMA interface" tab of the E-tile NativePHY IP.

• Unfortunately I don't see 66 option here.
• The only available option is 16, 20, 32, 40 and 64

However, there is very strict and complicated rule check implemented in E-tile NativePHY IP.

• The IP will prompt error in system message console if user selected wrong combination of invalid setting.\
• I highly encourage you to try out your desired setting directly in E-tile NativePHY IP to ensure it's valid combination of allowable setting

Thanks.

Regards,

dlim

[Deshi_Intel]

Hi Laszlo,

I hope I have answered your questions.

For now, I am setting this case to closure.

Feel free to post new forum thread if you still have further enquiry in future.

Thanks.

Regards,

dlim