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Nucleo virtual com port not working on Mac

JBill.10
Associate

I'm using an ST-Nucleo H743ZI on a Macbook running 10.14.3. The virtual com port basically doesn't work. I can send a few hundred bytes to the MCU at most, and then it stops transmitting.

I'm looking it at with a scope, so my actual MCU firmware is not an issue. The ST com port stops toggling the pin. After that, it won't send anything again until I power cycle the board, and then its the same issue.

I use a ton of other USB serial devices and they all work fine. It's not a bad board, as I've tried all 3 that I have, same results.

My ST-Link firmware is V2J32M22. I've also tried V2J33M25 (newest as far as I know), which not only doesn't fix the virtual com port, but also breaks the debugger so that OpenOCD can't connect to it.

Since Mac's just have a standard driver for USB-CDC devices, and it works fine with a ton of other USB serial devices, it can't be the driver. So that leaves the ST link MCU firmware as the weak link.

Has anyone else had this problem? Are there any workarounds, or is this just a bug that will never get fixed?

My only recourse at this point is to patch in an FTDI or Silabs cable to the UART pins directly. That's annoying, though not the end of the world.

Thanks!

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