How to debug FIFO_FULL?

I'm afraid tracking down the FIFO error could be tricky. Basically on STM32 the stuff that puts stuff in the FIFO is:

• USB Serial
  
• Normal Serial ports
  
• setWatch
  
  

And really that's about it. I guess the obvious thing is how much data is AzzyRF sending your board?

To do some debug, you could try clearing the flags with E.getErrorFlags and then check them again after any long-running functions you have - you might be able to find a function that runs so long that it's causing the overflow.

Or... it could be that you have code that is sending a lot of characters on serial? If so, that could be blocking the function that's sending and then causing you issues?

But yeah, you can increase the buffer size up to 256 (which uses 1.2k-ish of RAM) here: https://github.com/espruino/Espruino/blob/master/scripts/build_platform_config.py#L322

That might help? Although if your code is spending all its time busy I guess you might still end up hitting issues.