LPC MicrocontrollersのトピックCDC sample problem

CDC sample problem

lpcware — Wed, 15 Jun 2016 18:55:36 GMT

Content originally posted in LPCWare by gjdevos on Mon Jan 19 09:55:36 MST 2015
Our LPC4370 based system uses the USB CDC API. Occasionally, the host cannot communicate with the board.
I managed to reproduce the same problem by running usbd_rom_dfu-composite on the Lpc-Link2 board. When
running the attached python script in a loop, the LPC stops echoing the data after many iterations. I have only
seen the problem occur on a linux host. It does not happen on a Windows host using the same communication
script. The usbd_rom_dfu-composite sample includes the artf45032 patch for CDC.

Has anyone seen familiar issues in the CDC ROM implementation? Am I missing a patch? I'm using
LPCOpen V2.12.

Gert-Jan

Original Attachment has been moved to: serial.py_.txt.zip

Re: CDC sample problem

lpcware — Wed, 15 Jun 2016 18:55:37 GMT

Content originally posted in LPCWare by gjdevos on Tue Jan 20 03:18:55 MST 2015
Hi,

Here is some more information on this issue.

When the LPC stops sending answers, it is always after the first message in the script. An external
USB analyzer shows that the LPC no longer sends data in this case while in the debugger we see
that WriteEP is still being called successfully. I assume the CDC initialization somehow triggers a
problem in the LPC USB stack. Indeed the USB analyzer shows a slightly different setup
sequence for a Windows host as compared to the same script running on the Linux host.
When the problem happens, ioctl(USBDEVFS_RESET) makes the communication working OK
again.

Gert-Jan

Re: CDC sample problem

lpcware — Wed, 15 Jun 2016 18:55:37 GMT

Content originally posted in LPCWare by gjdevos on Thu Feb 12 08:02:06 MST 2015
We no longer see this problem after upgrading the linux kernel from 3.12 to 3.13.
The CDC issues appears to be a linux specific problem.

Gert-Jan