bidouilleelec:
Hello psmelakt"now the code works." : sure, one day or another you will have millis() >= 30000.
Crap. This is in setup, millis starts with zero and counts up, so "one day or another" happens after 30 seconds.
bidouilleelec:
Have you read post #6 ?
which is
Danois90:
You are calling "while(!Serial);" before "Serial.begin()" - that may be an issue.
Why should anyone read that irrelevant superstitious post anyway?