Serial Monitor requires reset to connect

Official Hardware UNO Family UNO R4 Minima
1

Hi,
I have seen various messages around this point, but none really solving my problem.
I create a very basic sketch with Serial.begin and Serial.println("Hello").
After downloading, the Serial Monitor remains empty.

  • Now, if I press the Arduino board hard reset, bingo ! I get my "Hello".
  • Issue is specific to R4 Minima (works fine with older R4)
  • I'm using IDE 2.3.4, and same behaviour if IDE is running on MacOS or Ubuntu...

Not critical (now I found the 'reset trick'), but painful...
Any feedback is welcome !

2

Not sure this is relevant, but it is necessary on some Arduinos, and IIRC, R4 Minima is one of those.
In setup(), after
Serial.begin();
try adding:
while(!Serial);
This will make setup() wait until the Serial instance is valid.

1 Like
3

Noy sure what your problem is. Some boards start with residual data in the Serial buffer, some don't start right away and both benefit from a press of the reset button. Be a Willow tree not a Walnut tree.

4

Yep ! The 'while(!Serial)' seems to solve my problem.
Many thanks !