Serial Monitor

If the board is not printing or not echoing typed characters, unplug and replug the board. Confirm that it mounts the USB drive.

Debugger

Most common issue is debugger breaking after stepping over a thread_sleep_for() without setting up the debug mode properly. Make sure your code always starts with:

#if defined(MBED_DEBUG) && DEVICE_SLEEP
HAL_DBGMCU_EnableDBGSleepMode();
#endif

• If debugger will not connect (due to above reasons or others), try:
  • running debugger again
  • clean build
  • unplugging the board (you might need to wait a while before you plug in again)
  • restarting mbed studio
  • restarting computer

It is a bit of a pain but it should work again eventually if you wait.

Coding

Floats not printing: make sure you have enabled floats to print in mbed_app.json in your root directory: "platform.minimal-printf-enable-floating-point": true,

Fault error: make sure the code has a while(1); at the end or is in a while(1) loop so it doesn’t crash.

Target board

If board won't configure automatically, try unplugging the board and plugging it back in again.

Mbed Studio

If it says it is offline, just close and restart it (it needs to be online to compile and sometimes it gets stuck).