Guest pipomolo42

FPGA only detected at 1.2V

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Guest pipomolo42

Hello,

My papilio behaves a bit strangely for a few hours, now.

When I plug it in, with the FPGA powered at 3.3V or 2.5V, it doesn't seem to start, and it isn't recognized by the papilio-prog or urjtag tool. papilio-prog -C returns only zeroes, and urjtag also complains about TDO being set to 0.

The F2232 show up correctly in dmesg and lsusb, though.

But when I set the jumper to 1.2V, the FPGA is correctly detected by both papilio-prog and urjtag, which might indicate that there is still hope…

I might also have flashed and erased the SPI flash earlier this evening using the various logic sniffer bitfiles available, but I don't know if or how it could be related.

Do you have any idea of what is happening here, and how I can fix this ?

Best regards,

Alex

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Hello pipomolo42,

It sounds like unfortunately you might have a bad Papilio... Where did you purchase it from? We can work on getting a replacement through whoever you purchased it from, or I can replace it as well.

It sounds like a hardware issue, but if you have access to another computer you might want to give it a quick test on a different computer just to be certain.

If you want to troubleshoot yourself, then it sounds like the problem exists between the FPGA and the FT2232. If the FT2232 is being detected properly then you will want to check for any solder joints on the JTAG pins between the FPGA and FT2232.

Sorry for the hassle, we will get this worked out for you.

Jack.

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Guest pipomolo42

Hi,

It sounds like unfortunately you might have a bad Papilio... Where did you purchase it from? We can work on getting a replacement through whoever you purchased it from, or I can replace it as well.

I ordered it directly through GadgetFactory (#429). But as I said in my previous post, it worked fine (well, I couldn't get the logic sniffer to work, but the FPGA was recognized, and I could program it) earlier  in the evening, so a cause for the failure could simply have been me not handling it properly…

It sounds like a hardware issue, but if you have access to another computer you might want to give it a quick test on a different computer just to be certain.

I tested it on two different computers, running GNU/Linux and Windows, with the same results.

If you want to troubleshoot yourself, then it sounds like the problem exists between the FPGA and the FT2232. If the FT2232 is being detected properly then you will want to check for any solder joints on the JTAG pins between the FPGA and FT2232.

I used a continuity tester to make sure that all the JTAG traces were OK, and found no problem. And as I said, it seems to work at 1.2V, but this voltage is not enough for the SPI flash or the FTDI UART channel to detect a logic "1".

I managed to borrow a Xilinx USB-JTAG cable, I'll make a few more tests to see if it really works, and also check the different voltage pins, but more clues would be helpful.

Alex

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