Terminate screen monitoring serial port

It's not corrupted. What's happening is that the cat command is getting some of the bytes, and your application is getting some of them. So when you run cat, any bytes read by it are missed by the app, and both cat and the app will see (different) partial streams that appear corrupted.

If you have a closer look at the broadcom datasheet specs of some iOT chipsets, you will see there white in black, that the serial communication services implementation in ARM iOT are partial emulations of the common 16550 serial chipsets you find commonly in the PC world. As far as I remember, they write explicitly the emulation only suports a small subset of the 16550 services.

So they provide only a good enough subset of the services "full blown UARTs" provide.

Bottom line, do not count on it supporting all the usual functionalities at 100%.