Tang Nano Problem

[TheFlav]

FYI On my Tang Nano, when I did all of this.

    cd examples
    yosys -p "synth_gowin -json blinky.json" blinky.v
    nextpnr-gowin --json blinky.json \
                  --write pnrblinky.json \
                  --device GW1NR-UV9QN881C6/I5 \
                  --cst tec0117.cst
    gowin_pack -d GW1N-9 -o pack.fs pnrblinky.json
    # gowin_unpack -d GW1N-9 -o unpack.v pack.fs
    # yosys -p "read_verilog -lib +/gowin/cells_sim.v; clean -purge; show" unpack.v
    openFPGALoader -b tangnano pack.fs # Tang Nano

I could not get it to finish loading. I tried a bunch of stuff. I even replaced the firmware of the CH552 chip.

Anyway, after a lot of flailing and reading, I tried some other .fs (from https://github.com/racerxdl/tangnano-yosys-hello) and that worked fine.

After that, in apicula/examples, I did a full make. Then, this one worked openFPGALoader -b tangnano blinky-tangnano.fs

So, maybe "pack.fs" isn't what should be on the main README?

[pepijndevos]

You are passing the wrong device for all the commands. You're not the first, so I GREATLY welcome a PR to the readme that suggests wording that would have made this clear to you.

Or maybe people just skim the readme and we should copy-paste the commands for every supported board. Or put placeholder commands <DEVICE> so that the user is forced to think about the parameters.

Every reference to a device family GW1N-9, a specific device GW1NR-UV9QN881C6/I5 and a specific board tec0117.cst, tangnano needs to match. Note that you can pass GW1NR-UV9QN881C6/I5 to gowin_pack as well for uniformity.

[trabucayre]

ASAP I add check to don't flash a bitstream when it's fs IDCode didn't match FPGA IDCode.

[TheFlav]

As a bit of background, I was trying to understand the toolchain. I just received the Tang Nano, and I wanted to try to use it on my Mac without needing the official tools and Windows.

The commands I did

            cd examples
            yosys -p "synth_gowin -json blinky.json" blinky.v
            nextpnr-gowin --json blinky.json \
                          --write pnrblinky.json \
                          --device GW1NR-UV9QN881C6/I5 \
                          --cst tec0117.cst
            gowin_pack -d GW1N-9 -o pack.fs pnrblinky.json
            openFPGALoader -b tangnano pack.fs # Tang Nano

were directly copy/paste from the readme.md. I didn't even consider that I needed to edit the device until you just mentioned it here. I now see that the readme mentions the supported boards and their devices, but I would not have realized that it was the problem here at all. I think maybe the readme.md could be updated to specifically tell the reader that they need to add in the based on their board.

I assume this issue also applies to the cst file, right?

As trabucayre mentioned, adding that check during the flash process would be very helpful, but that'd be in openFPGALoader, right?

I also think, if we're talking about editing the readme.md, that it's worth pointing out that it is already all set up properly in the Makefile.

If you just do

    make blinky-tangnano-prog

it will run all the commands properly.

    yosys -p "synth_gowin -json blinky.json" blinky.v
    nextpnr-gowin --json blinky.json --write blinky-tangnano.json --device GW1N-LV1QN48C6/I5 --cst tangnano.cst
    gowin_pack -d GW1N-1 -o blinky-tangnano.fs blinky-tangnano.json
    openFPGALoader -b tangnano blinky-tangnano.fs

so, MAYBE, the readme should just say

"From there, compile a blinky with one of these commands"

    make blinky-tangnano
    make blinky-runber
    make blinky-tec0117

and upload it with one of these commands

    make blinky-tangnano-prog
    make blinky-runber-prog
    make blinky-tec0117-prog

Because, I figured it out once I understood what was going on, but I didn't really need to understand it at this point in the exercise. I just wanted to see if all the tools were working properly. Since the process failed at openFPGALoader, I assumed there was a problem with it or with my CH552.

[trabucayre]

I've updated openFPGALoader to check coherence. Now this type of issue will not happens anymore.

[pepijndevos]

Actually #30 aims to change the readme in pretty much this way, but wasn't merged because it states in very uncertain terms things that should be unambiguous. Does that look good to you? Feel free to chime in with improvements. Maybe I should just merge it and fix it up myself.

[TheFlav]

I like this addition, "The example below is for the Trenz TEC0117. For other devices, use the device IDs listed above, and replace tec0117 with runber or tangnano accordingly."

I also see that he changed the 3 openFPGALoader commands to just one, BUT he should have added a better comment there.

One thing that tripped me up with the readme was that it says "compile a blinky" and then it shows the steps to do that. It was obvious to me that there were 3 options for the openFPGALoader command, and that made me choose one of them (for my board). BUT there weren't options for the previous commands.

So, I think maybe something like this is better.

The example below is for the Trenz TEC0117. For other devices, use the device IDs listed above, and replace tec0117 with runber or tangnano accordingly.

    cd examples
    make make blinky-tec0117-prog # or blinky-runber-prog or blinky-tangnano-prog

or

    cd examples
    yosys -p "synth_gowin -json blinky.json" blinky.v
    nextpnr-gowin --json blinky.json \
                  --write pnrblinky.json \
                  --device GW1NR-UV9QN881C6/I5 \  #set this to your device like GW1NR-UV9QN881C6/I5, GW1N-LV1QN48C6/I5, GW1N-UV4LQ144C6/I5, etc
                  --cst tec0117.cst  #choose the cst file for your board
    gowin_pack -d GW1N-9 -o pack.fs pnrblinky.json # You may need to change GW1N-9, runber uses GW1N-4 and tangnano uses GW1N-1
    # gowin_unpack -d GW1N-9 -o unpack.v pack.fs
    # yosys -p "read_verilog -lib +/gowin/cells_sim.v; clean -purge; show" unpack.v
    openFPGALoader -b tec0117 pack.fs  #select tec0117, runber, or tangnano

[pepijndevos]

Ok I updated the readme. I hope this makes it clearer.