nRF52840 Feather Express, USB serial strange behavior

Development Platforms
1

Hello,
I’m having a problem with a Adafruit nRF52840 Feather Express. Sometimes the serial transmission doesn’t seem to work when I run this simple code:

#include <bluefruit.h>
void setup()
{
  Serial.begin(115200);
  while ( !Serial ) delay(10);   // wait for native usb

  Serial.print("Hello world");
}

void loop {}

9 times out of 10, the serial terminal does not display anything, and somethimes it works. When I put the Serial.prinln() in the loop with a delay. The serial message is displayed but the delay is in the middle of the message.

For example: Hel [delay] lo world Hello [delay] world H [delay] ello world

What I tried:

  • Change the “Reopen Serial Monitor Delay” setting
  • Change the baudrate of the bus

Does anyone have any idea where the problem might come from?

Thanks

2

No line ending my be troublesome. Does the problem appear with Serial.println() as well? Does delaying a little bit after the while loop is exited help? Does a Serial.flush(); call after the print help?

3

Yes it changes nothing.

Oh yeah great, it resolve the problem of the cutted messages :+1:

No it doesn’t chage anything.

But I believe I found the solution ! The opening of a new Serial Monitor doesn’t reset the nRF52840. Only the switch on the board can reset the uC. If I press the reset button and then open a new Serial monitor it works ! :slight_smile:

Edit: false alarm
it seemed to work but no, the problem with the serial monitor is always there :frowning: