CDC UART nRF52832 Virtual Box Linux Guest not working

[darioclock]

Hello,

I have been trying to communicate via UART with the Nordic nRF52832 DK (10040) in a Linux (Fedora 26) Guest on Virtual Box. The guest is Windows 7.

The JLink drivers seem to work properly for device programming. However, when I connect a serial terminal to ttyACM0 no data is received despite being able to open the port. I tried using minicom and gtkterm with equivalent result.

If I run the same program in the Windows guest and listen with Putty I get the expected data.

JLink Linux = V620c JLink Win = V620d

Any idea on I could tackle the problem and have the UART working in the VM?

[darioclock]

I found out that the problem is related to the EHCI Controller (USB2.0) of virtual box. Using either USB 3.0 or 1.1 controllers allows me to send and receive data to/from the terminal.

I had to run the board through a power cycle to have the in stream from keyboard working again.

Also, apparently, the physical USB port that the board is connected to is also important. Connecting to a port expander (such as the ones that come with SD card readers etc in prefab desktops) won't work for me, I need to use an USB port directly located on the motherboard.