Cannot connect two EVK boards to single computer

[danf]

I have two development kit boards (MIMXRT1020 EVK Board and MIMXRT1010 EVK Board).

They are connected to each other using SPI.

When I connect one to the computer (Macbook Pro) using a USB C --> MicroUSB cable it shows up and I can run the MCUExpresso debugger. If I then connect the second board using another USB C --> MicroUSB cable, the second device is not seen. I get "LinkServer not found" when looking for probes. Looking in /dev I only see one /dev/cu.usbmodemXXXXX .

If I disconnect both boards and reconnect the second board, it then works fine. It doesn't seem to matter which board is connected first. Also either cable/USB-C port works, it just seems dependent on which one is connected first. The first (either 1020 or 1010) will work and the second one won't.

Both boards do get power. When I pull the cable from the non-working board I get the OSX notification "Eject 'MAINTENANCE' before disconnecting or turning it off". For the working board it says "Eject 'RT1010-EVK' before disconnecting or turning it off". So the board is there, it's just labeled "MAINTENANCE" somehow.

Thoughts?

Thanks for your help!

Dan

[danf · Accepted solution]

Update: I think this has to do with connecting the two boards together. Without the connection I can see both virtual COM ports. I changed how the boards were powered and that partially resolved the problem. However, when I pressed the Power on Reset button, the EVK1010 board was no longer able to be seen and the green power light went off. Please closing this thread until I can determine with more clarity what is happening.