USB CDC Virtaul COM between host and device failed

[huishao2]

Hi -

I have a USB host of k20d76m running MQX3.8 and a USB CDC device of k20d50m running MQX4.1. The USB CDC device has no problem talking to a host PC via hyper terminal but there is no communication happens when connecting to the host. That means, when host sends bytes to device, it reads nothing back from the  device. The enumeration is done successfully in this case. But data communication failed, anyone has insights or comments on it?

I traced into USB host source, noticed that when usb_class_cdc_in_data_callback() of usb_host_cdc.c is called, the status is 0x97 which means USBERR_TR_FAILED.

Thanks!

Hui

[soledad]

Hi,

Could you please check the below link???

USB CDC Virtual Com Example

Have a great day,
Sol

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[huishao2]

Hi Sol

Thanks for your help. I think I have worked around the issue that was caused by fact that my CDC device bootup time was longer than my CDC host. The workaround was to delay the Reset Bus Condition to cater for slower CDC device.

Hui

[soledad]

Hi,

Thanks for sharing your solution,

Regards

Sol