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6 years, 2 months ago.
K64F USB port failure with shield attached
I'm trying to do development on a K64F with a DFRobot SIM808 GPS/GPRS/GSM Shield attached. The shield requires external power, so I've attached power to Vin. This disables the USB port (I think by design) and the mbed compiler complains that the target board is not attached.
So I tried turning off the external power supply just to load the .bin, but the load operation hangs and eventually the compiler says, "ERROR: Unknown Error: init() should return None, not 'bool'.
It seems I'm only able to load the .bin by completely removing the shield. That's terribly inconvenient, is this really how I must proceed?