Feature request: Support Lilygo T-FPGA board with GWU2X USB-to-JTAG bridge

[janschiefer]

Hi,

I just picked up an interesting and cheap FPGA board - Lilygo T-FPGA with an Gowin GW1NSR-LV4CQN48PC6/15 and an ESP-S3 as an IoT solution.

Interestingly this board seems t use the relatively new GWU2X application specific chip as an USB to JTAG-brigde.

Any chance flashing this board over USB will be supported in the future?

Specs: https://www.lilygo.cc/products/t-fpga
GIthub repository: https://github.com/Xinyuan-LilyGO/T-FPGA/tree/main
Board schematic: https://github.com/Xinyuan-LilyGO/T-FPGA/blob/main/schematic/T-FPGA-V1.0%20CORE.pdf
Documentation for the GWU2X USB to JTAG bridge: https://alcom.be/uploads/Gowin-UG1000-1.0E_GWU2X-Datasheet.pdf

[trabucayre]

I have already seen this board, and I think I have to bought one (or ask for free sample ;-) ).
The main issue with gowin's stuff is the totally lake of documentations, most of the time you have partial/incomplete, wrong documentations.

[janschiefer]

Do you speak Mandarin? ... https://cdn.gowinsemi.com.cn/UG1003.pdf

[trabucayre]

Not really, but this doc explain how to use a gowin's library to use this chip no?
My interest isn't to use an external library but implement the protocol ;-)
But I assume wireshark will be my friend.

[trabucayre]

I have received my board today.
After a quick search on gowin website I have found a doc about protocol (instructions to send).
It looks really similar to FTDI's MPSSE.
I think it's not possible to use directly libftdi but this seems not really hard to implement. I will try it ASAP.

[janschiefer]

Very nice!

[zJudGenie]

I also bought this cool board, I'm trying to use it with the toolchain yosis+nextpnr+gowin_pack+openFPGAloader.
The GW1NSR-4C is supported by the apicula project but I'm struggling to flash the bitstream to the FPGA through the Gowin Programmer as it is complaining about a wrong ID CODE and I don't know why.

So I'm waiting that the GWU2X will be supported by openFPGAloader because it is a really cool project, I can help with testing stuff.

Also, I found a little bit of documentation here that should be helpful to add the support.

Thank you.

[trabucayre]

Hi.
Gowin GWU2X and lilygo T-FPGA are now supported.
Is it good to you?

[zJudGenie]

Yes, thank you, I tried flashing to SRAM with -m and it works, when I try to write to flash with -f I get, during the Erase FLASH phase, Write failed with error -7, Failed to program FPGA: std:exception

[trabucayre]

Thanks for your feedback: I will try with a different computer to see if it's an hardware issue.
Could you share your setup ? OS / VM ?
Thnaks

[zJudGenie]

I tried with this example https://github.com/Xinyuan-LilyGO/T-FPGA/tree/main/example/FPGA/led/src.
I synthesized it with the Gowin IDE educational 1.9.9 on Windows and then I used Ubuntu 22.04 on WSL to flash it, using openFPGALoader

[trabucayre]

Thanks for informations. Is it possible to you to test with a native linux? I have seen lot of issues with WSL (and I have to find why).

[zJudGenie]

I noticed this strange behavior, it seems that when I use the verbose flag the IDCODE gets corrupted

[zJudGenie]

And then, trying to detect the FPGA with openFPGALoader --detect --cable gwu2x gives the same error

[zJudGenie]

This is the output I get when, after rebooting the device, I try to flash it with -f -v so in verbose mode

[trabucayre]

This timeout (-7) is fixed: stupid optimisation before pushing: 65356== 0x10000 ie needs 17bits but I have used a 16bits variable...
But now it seems to have a problem with the bitstream: I obtain an error (mismatch between read checksum and computed). Maybe another issue with a variable or a size. But I have to check if the same FPGA and an FTDI I have a similar error or if it's gwu2x related bug.

[zJudGenie]

If you have an FTDI and a 13-pin flat cable you can directly access JTAG lanes using the white connector as you can see here

[trabucayre]

Unfortunately no. I will switch to my tangNano 4k to check before continuing to debug this board.

[trabucayre]

With tangnano4k Flash sequence is working: I have to recheck everything here to see where is issue with gwu2x.