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USB CDC-ACM data channel not responding when connected to virtual machine

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Hi,

I am using the sample application from the "an-r11an0171eu0100-synergy-usbx-device-class-cdc-acm-mod-guide", to test a simple USB CDC-ACM communication. My setup is - host Windows 7 64 bit, S5D9-PK development board.

I also have a virtual machine (VM) with Windows 7 64 bit, running on VMWare Workstation 14 Pro.

When I start the sample application, the device is connected to the PC and everything works Ok - from a terminal emulator I can send characters and see the board echoes them back. If I close the terminal emulator, and connect the device to the VM, the device enumerates correctly - I can see it as a COM port in the Device Manager. However, when I open a terminal emulator on the VM, I cannot send or receive anything. Disconnecting from the VM and re-connecting back to the host - device is still in that state - enumerates Ok, but no serial communication is possible. If I power cycle the device (or do a hard RESET) then it is back to normal.

I used USB analyzer to capture some more data. Here (usb-1.png) is what the USB traffic looks like when the device powers ON, connected to the host, and I send some data to it using a terminal emulator:

And here is what the traffic looks like when I disconnect the device from the host and connect it to the VM and try to send data from a terminal emulator on the VM (usb-2.png):

You can see that all OUT transactions are NACK.

I also checked ux_cdc_device0_instance_deactivate() - it is not invoked when the device is detached from the host and attached to the VM.

Any ideas how to resolve this?

Thank you,

D.


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