2.1.1 spits out garbage to Serial Monitor then Proper Output

Development Tools IDE 2.x
1

I'm running 2.1.1 on Win10 Pro with a Uno R3 connected via USB.
The code and the Serial Monitor are set to 9600 baud.

When I compile and upload the Serial Monitor displays some garbage...
Then displays the proper out put.

Here is the output...
(note first line is actually a bunch of boxes with H, another box and j at the end)

�H�j
3
ode End
Start Now
5
1.00
1
6
4
Code End

Here is the Code...

void setup() {     
  Serial.begin(9600);
  Serial.println ("\nStart Now");
  Serial.println(constrain(5,1,6));
  Serial.println(sin(1.57));
  randomSeed(analogRead(0));
  for(int i = 0; i < 3; i++){
    Serial.println(random(1,10));
  }
Serial.println("Code End\n");
  }
void loop() {
}

The more code I add the more garbage is sent to the Serial Monitor before the expected output appears on the monitor.
Thanks for any help.

2

Try adding Serial.flush(); as the last command in setup() to force the output of whatever is in the Serial buffer before moving on

You might also consider using a faster baud rate such as 115200

3

Hi @fran_3. The Arduino IDE developers are tracking this bug here:

If you have a GitHub account, you can subscribe to that issue to get notifications of any new developments related to this subject.