Getting constant PWM value based on user input from serial monitor

Question

I am trying to get a constant PWM value from the PWM pin based on the user input. For example: the user hits 1, the output PWM value is 100, if it is 2 the output would be 200. This will continue till the user enters a new number. The issue I am having with my code is when I enter a number, the output of the PWM goes to that value for about a second and then goes back to 0. Can you please let me know what I am missing?

// Sketch: Blinking two LEDs by user
int test_pin=2; // declare pin10 as ledpin
int PWMvalue; // variable to store the number of blinks
void setup()
{
 Serial.begin(9600);
}
void loop()
{
 Serial.println("What is the new speed?"); //Prompt User for Input
 while (Serial.available() == 0) {
 // Wait for User to Input Data
 }
 PWMvalue = Serial.parseInt(); //Read the data the user has input
 
 if (PWMvalue==0)
 {
 analogWrite(test_pin,0);
 }
 else if (PWMvalue==1)
 {
 analogWrite(test_pin,100);
 }
 else if (PWMvalue==2)
 {
 analogWrite(test_pin,200);
 }
 else if (PWMvalue==3)
 {
 analogWrite(test_pin,300);
 }
 else if (PWMvalue==4)
 {
 analogWrite(test_pin,400);
 }
 else if (PWMvalue==5)
 {
 analogWrite(test_pin,500);
 }
 else if (PWMvalue==6)
 {
 analogWrite(test_pin,600);
 }
 else if (PWMvalue==7)
 {
 analogWrite(test_pin,700);
 }
 else if (PWMvalue==8)
 {
 analogWrite(test_pin,800);
 }
 else if (PWMvalue==9)
 {
 analogWrite(test_pin,900);
 }
 else 
 {
 analogWrite(test_pin,1023);
 }
 
 Serial.print("The user has choosen the number:");
 Serial.println(PWMvalue);
 Serial.println(" ");
}
```

• Dave: I am using Arduino MKR NB 1500. I am using PWM pin 2
• Juraj: set Line ends to none in Serial Monitor. line ending counts into available(). readInt waits one second for number, then it returns 0.
• Dave: setting the line ends to none worked. Thanks Juraj!
• jsotola: why have you not included the serial console printout?

Answer 1

You wait for user input with a while (Serial.available() == 0), the you read the input with Serial.parseInt(). parseInt will wait a second for digits. It will end on a non digit character or timeout and return the number corresponding to received digits. If no digits were received a 0 is returned.

Serial Monitor has Line end setting. If there is some line ending selected, it will send line ending character(s).

Your waiting loop while (Serial.available() == 0) will end on line ending character which followed the number processed in previous loop. parseInt will not find a digit so it times out after a second and returns a 0, which causes setting the PWM to 0.