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USB / Transition from HS to FS USB
« on: February 23, 2022, 10:33:50 PM »
Hi everyone,
We've been forced by the chip shortage to move from our MK66FN2M0 chip with HS USB to a MK24FN1M0 that only has FS USB. While initial very basic testing looked good (after some advice from Mark), we've hit some serious stability issues. Essentially our app involves sending ~850 bytes at 10Hz to the PC, which should be more than enough for the 12Mbps of FS USB, but we're seeing serious stability issues. I've captured a log of such an instance, opens with USBlyzer, a USB sniffing tool. (https://www.usblyzer.com/download.htm).
I also took a screenshot of when the issue occurs in the log. The odd thing is that this seems to be PC-related. A faster PC is much more unlikely to generate the problem, while slower PCs trigger it almost immediately. The faster PCs are able to keep a stable connection for minutes at an end. I'll be doing further troubleshooting tomorrow, as I'll connect some debug pins and try to see whereabouts in the USB flow the problem appears, but any tips would be greatly appreciated. As with most development projects, this is also running late
Thank you!
We've been forced by the chip shortage to move from our MK66FN2M0 chip with HS USB to a MK24FN1M0 that only has FS USB. While initial very basic testing looked good (after some advice from Mark), we've hit some serious stability issues. Essentially our app involves sending ~850 bytes at 10Hz to the PC, which should be more than enough for the 12Mbps of FS USB, but we're seeing serious stability issues. I've captured a log of such an instance, opens with USBlyzer, a USB sniffing tool. (https://www.usblyzer.com/download.htm).
I also took a screenshot of when the issue occurs in the log. The odd thing is that this seems to be PC-related. A faster PC is much more unlikely to generate the problem, while slower PCs trigger it almost immediately. The faster PCs are able to keep a stable connection for minutes at an end. I'll be doing further troubleshooting tomorrow, as I'll connect some debug pins and try to see whereabouts in the USB flow the problem appears, but any tips would be greatly appreciated. As with most development projects, this is also running late
Thank you!