USB Corrupt CRC in packet

allan2 · ‎2012-09-05

Posted on September 05, 2012 at 22:44

I have a situation where the registers appear to be set up correctly, but when I put data into a transmit FIFO, the output on the USB wires is a single byte with a checksum of 0x0000.

Put many bytes into the FIFO

a - One byte comes out

b - The wrong byte comes out

c - The packet has a checksum of 0x0000 and is rejected by the host.

Does anybody have any experiance with this error, or any idea what can cause it?

Thanks

#usb #back-packets #crc-error

Tesla DeLorean · ‎2012-09-05

Posted on September 06, 2012 at 00:40

What part, exactly?

What library, a standard ST USB library, or a register level implementation?

Does the FIFO expect 32-bit words, and not bytes?

Sounds like things haven't been initialized properly, or the USB peripheral is trying to purposefully corrupt the data, perhaps detecting an underflow issue.

Have you built and tested any of the example code?

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