Qwiic Pro Micro - USB-C slow serial startup

Development Boards Arduino
1

This is more to document this for other users than a “cry for help”, but I noticed something about my Qwiic Pro Micro - USB-C (OK, I’m actually using that limited-distribution “Boogie Board” from a few months ago).

In the “setup()” function, when I follow a Serial.begin(9600); (and same result using 115200) with a Serial.println( “some text” );, it does NOT display “some text” on the Serial Monitor. If I put a delay(1000); between the Serial.begin(); and the Serial.println( “some text” );

This is a bit of a problem when you need to print diagnostic messages (e.g., “xxx not found - freezing”, as in a lot of the examples).

FWIW I’ve tried shorter delays, and sometimes one as short as 774 work, but 1000 seems to be reliable.

At first I thought I’d zapped my Boogie Board, expecially after I’d tried some ill-advised combos (programming a 5V board as a 3.3V board) but then came across the instructions of what to do to “un-brick” it.

I’m using a MacBook Pro with OSX 10.13.6 (“High Sierra”), and Arduino 1.8.13.

2

This is a known limitation of using the ATMega32U4 microprocessor with the Arduino IDE. I always add the following code to my programs that output using serial():

  Serial.begin(115200);
  #if defined(__AVR_ATmega32U4__)
  delay(2000);
  #endif
3

Check the post over at the link below, I think that might be helpful for your situation with the Pro Micro or any Arduino board that connects directly to USB.

https://arduino.stackexchange.com/quest … ile-serial

4

Thanks Guys!

I’ll probably go with SV-Zanshin’s idea, as the one suggested by TS-Chris will likely have problems on projects that are not always connected to a USB link.

But, again, my thanks for both ideas!