atmega328pb USART RX Start Interrupt

[jaka87]

Hi.

If i understand correctly there is a possibility with the atmega328pb to wake up when i receive serial message. What i did is put UCSR0D = 1 << RXCIE1 | 1 << RXSIE | 1 << SFDE; in setup which (according to my understanding) enable RX flag. Then i tried to write ISR like this...

ISR(USART1_RX_vect)
{
// do something
}

which should trigger on new RX on Serial1 but i cannot compile it because i get

/tmp/arduino_build_715208/../arduino_cache_885861/core/core_f3204311d3bdf6a1bbb83a41a5a6f099.a(HardwareSerial1.cpp.o): In function `__vector_28':
/home/jaka87/.arduino15/packages/MiniCore/hardware/avr/2.1.3/cores/MCUdude_corefiles/HardwareSerial1.cpp:48: multiple definition of `__vector_28'
/tmp/arduino_build_715208/sketch/UZH.ino.cpp.o:/home/jaka87/Arduino/UZH/UZH.ino:76: first defined here

I found very little information about this online so im hoping if someone here would know how to get RX wake up working. Help is greatly appreciated. Regards, Jaka

[MCUdude]

If you want to use the ISR directly you can't use Serial1 at all. Replace all your Serial1 related code and it should work.

[jaka87]

Thank you for explanation. If i removed Serial1 it does compile but it doesn't work. I dont know if i should put different flags?

I tried

ISR(USART1_RX_vect)
{
  DEBUGSERIAL.println("interrupt");
}

and i get no response from serial device

[MCUdude]

Well, that's up to you to figure out 😉 For some reason, the ISR isn't firing. You're now running bare metal, so this isn't really MiniCore's fault. Just bear in mind that there are several USART1 registers that need to be initialized before you can use the serial port. Similar to what Serial.begin() does.

[jaka87]

I finally figured it out in case someone else in the future will be having the same problem. For Serial1 register should be set UCSR1D = (1 << RXSIE) | (1 << SFDE)

and then use ISR. In my case i only use it to wake up the device. There is no need to rewrite hardware serial.

ISR(USART1_START_vect){
countWake++;
}

Like MCUdude said its not really MiniCore related.