Describe the problem

When a sketch transmits data via the Monitor object, the messages arrive out of order and with incorrectly placed line breaks.

To reproduce

1. Create the following sketch:

   #include <Arduino_RouterBridge.h>
   
   void setup() {
     Monitor.begin();
   }
   
   void loop() {
     Monitor.print("Reading 1: ");
     Monitor.println(1234);
     Monitor.print("Reading 2: ");
     Monitor.println(4567);
     delay(500);
   }

2. Upload the sketch to an UNO Q board.
3. Open Serial Monitor.

🐛 The output from the sketch is not as expected:

Reading 1: 1234Reading 2: 4567
1234Reading 2: 4567
Reading 1: 

Reading 2: 4567Reading 1: 1234

Reading 2: 4567Reading 1: 1234

Reading 2: 45671234Reading 1: 
Reading 2: 4567
1234Reading 1: 1234Reading 2: 
Reading 1: 4567
Reading 1: 

1234Reading 2: 4567
Reading 2: 4567Reading 1: 1234
Reading 1: 
1234Reading 2: 4567

[...]

Expected behavior

Output is received in order:

Reading 1: 1234
Reading 2: 4567
Reading 1: 1234
Reading 2: 4567
Reading 1: 1234
Reading 2: 4567
Reading 1: 1234
Reading 2: 4567

[...]

Arduino_RouterBridge version

0.3.0

Additional context

We are seeing a spike of reports over the course of last few days. This seems to correlate with recent releases

• "Arduino UNO Q Board" platform (arduino:zephyr) version 0.53.0
• Arduino App Bricks version 0.6.4

Originally reported at:
https://forum.arduino.cc/t/why-an-update-messed-up-monitor-print/1427515

Note this:

I had my first simple sketch working then updated with a new patch for the MCU. Now the print formatting using Monitor is all over the place

Additional reports

• https://forum.arduino.cc/t/no-softwareserial-on-uno-q/1425534/8
• https://forum.arduino.cc/t/zephyr-wish-there-was-standard-way-to-speed-up-spi-operations/1426772/3
• https://forum.arduino.cc/t/arduino-uno-q-serial-monitor-broken/1427596
  • They reported the following result from rolling back their arduino:zephyr installation to 0.52.0:

    Working fine in Arduino App Lab

• https://forum.arduino.cc/t/stable-multiprocessing-readme/1427828/53
• https://forum.arduino.cc/t/uno-q-monitor-garbled/1427874

  I uploaded extensive code, monitor worked GREAT. Flawless!!
  Then I downloaded app lab, set up the linux side.
  No apps are running. Yet, monitor is now completely garbled

• https://forum.arduino.cc/t/uno-q-serial-println/1428801/5
• https://forum.arduino.cc/t/uno-q-serial-monitor-strange-output/1429225
• Output sent via Monitor object of Arduino_RouterBridge library arrives out of order and corrupted arduino/ArduinoCore-zephyr#322 (comment)