Adafruit feather 32u4 FONA waking up

Projects Programming
1

I can successfully put my Adafruit feather 32u4 FONA to sleep by using the Low-Power library: GitHub - rocketscream/Low-Power: Low Power Library for Arduino with the function: LowPower.powerDown(SLEEP_FOREVER, ADC_OFF, BOD_OFF);

With an external interrupt the FONA wakes up again and is functional EXCEPT that it cannot write to the Serial Monitor. Nothing is output but I can have the FONA blink leds and do whatever else. I call Serial.begin(9600 (or whatever)) to no avail.

Anyone got a clue why the serial monitor is not functional after a sleep?

2

Anyone got a clue why the serial monitor is not functional after a sleep?

The application running on the PC is NOT affected by the feather going to sleep.

3

I suspect that this happens because you loose the serial port on the PC when the 32U4 goes to sleep.

When this happens the file handle that the serial monitor uses is gone but the serial monitor does not realise this. I have similar symptoms with a Leonardo and RealTerm when I disconnect.

Only solution to my knowledge is to close and open serial monitor which destroys the old handle because the serial port is closed and creates a new one when the serial port is opened again.

4

For anyone looking for an answer to this. This thread has a working solution: http://www.rocketscream.com/blog/forums/topic/adafruit-feather-32u4-fona-wakeup-no-serial-print/

5

Thanks for the feedback.