windows usb device disconnect reconnect

[Keith4DSmith]

I am using a Kinetis Freedom K22F evaluation board. I have a program running that enables a USB CDC VCOM device.

Windows sees the device just fine and communication is not a problem.

The problem I am having is each time I restart the debug session (I am using Segger J-Trace), I have to physically unplug and replug the USB CDC VCOM cable so I can talk to the device again.

I am using either PuTTY and RealTerm to communicate with the device.

Is there some 'reset' register or reset sequence available with the K22F eval board that one can use to 'simulate' the disconnect and reconnection of the USB device?

[victorjimenez]

Hello Keith,

I'm making tests on my side to reproduce this behavior. Could you please tell me which version of Windows are you running? 

Regards,

Victor. 

[Keith4DSmith]

Windows 7 Enterprise Service Pack 1

Details of usbser.sys at attached in jpg

[victorjimenez · Accepted solution]

Hello Keith,

Thanks for providing more information. I was able to reproduce the behavior you mentioned using Windows7, the example dev_cdc_vcom_bm of the SDK v2.41 and Tera Term.

Please refer to the readme file about this behavior:

<MCUXpresso_SDK_Install>/boards/<board>/usb_examples/usb_device_cdc_vcom_lite/<rtos>/readme.pdf

Since there is no dynamic detection between host and device, the COM port must be closed from the terminal tool prior to plug-out/reset the CDC device. Or the CDC device won't get recognized next time you plug-in with the COM port still opened.

Hope it helps!

Victor.

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