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Wireshark usb protocol2/16/2023 ![]() ![]() ![]() In my code only the EP0 (Control) is OR-ed with XUD_STATUS_ENABLE. Anyhow, the problem is, that isochronous communications continues and the host always logs the EPROTO error at the response. Presumably, the ESD test causes a bit error. no response packet received within the prescribed bus turn-around time.USB isodesc 0 (4 bytes)Īccording to USB Error codes EPROTO means: URB transfer type: URB_ISOCHRONOUS (0x00)Ĭopy of Transfer Flags: 0x00000204, No transfer DMA map, Dir IN Here is the output of the first erroneous USB frame, that wireshark has logged:įrame 193151: 84 bytes on wire (672 bits), 84 bytes captured (672 bits) on interface usbmon2, id 0 I suspect that I could have found the error at another endpoint as well at first. The first communication error I have found, happens to the endpoint for isochronous stream in. The sound card uses multiple endpoints, including an endpoint for audio streams in and out. I have sniffed the USB communication with Wireshark/USBmon under linux and I was able to identify many communication errors. When I output music and penetrate the sound card with ESDs, the output stops and the mixer doesn't work anymore. The firmware works fine under normal conditions. I have developed an USB sound card with an own firmware implementation (inspired from the XMOS UAC project).
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