lpcware

USBCDC - VCOM Failure

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by cmcquaid on Sat Mar 10 12:44:25 MST 2012
If anyone out there is using USBCDC, could you look at D+ or D- and tell me if you see something funny?

I would expect to see traffic in short bursts, once per millisecond, but I see almost constant activity. If I turn on an LED during CDC_BulkIn, I can see it gets called almost continuously. Curiously, other examples based on the same stack are well-behaved.

I have almost given up on getting USBCDC to work on the LPC1343. It does work for me, but only up to a point. I need to report 3 signed bytes at 100Hz and the best solution I have runs for 30 seconds or so, then hangs for a few minutes before repeating the cycle.

I've tried starting from several different examples. I've tried them unmodified. I've used proper buffering, throttling based on SOF, inserting Zero Length Packets. I've also tried using an LPC1769 instead. I've tested on XP and Windows7-64bit.

This is a pro-bono project, so I'm inclined to take the easy way out and use something that 'just works'.

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