H-bridge problem

Projects Programming
1

My code does a really basic motor spin clockwise for 3 seconds and then rests for 3 seconds before repeating.

My code was working, and then today(without changing anything) it stopped working. In order to get it working again I had to include a line that sets the H-bridge 'reset' pin to HIGH. (After some research I found the default value should be HIGH)

Why am I now required to set the value to HIGH? Is it ok to keep doing this? And is the fact that the H-bridge is not setting the reset properly a sign of a problem?

Any help is greatly appreciated! Let me know if any other information is needed.

Setup:
Arduino Uno
Pololu md07a H-bridge (Pololu High-Power Motor Driver 18v15)
DC motor

Code:

// Basic motor spin

// Assign Pins
int dir = 1;    
int pwm = 2;     
int reset = 3;
//Variables
int speedOfRotate=255;

void setup() {
  // put your setup code here, to run once:
  pinMode(dir, OUTPUT);  
  pinMode(pwm, OUTPUT);
  pinMode(reset, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
/////////////////////////////////////////////////////////////////////////  
//Code only works with the following line:
  digitalWrite(reset, HIGH); // reset h-bridge
//////////////////////////////////////////////////////////////////////

   //Turn clockwise
    analogWrite(dir, 0);   
    analogWrite(pwm, speedOfRotate);
    
    delay(3000); //waits for 3 seconds
    
    
    // Do nothing  
  analogWrite(dir, 0);
  analogWrite(pwm, 0);
  
  delay(3000); //waits for 3 seconds

}  //End loop
2

If you don't do anything with a pin it is by default an input, that is it is high impedance.
The h-bridge is a very very weak pull up so the input floats high. But this is just on the edge of working and the slightest thing can upset this.
So you have been lucky that it functioned, but it only just.

Saying something is fine just because it functions for you is the source of a lot of stupid circuits you find on the Internet.

3

Thank you very much.