Increment error help

[colin_coder]

I'm writing a code that is supposed to count how many times a button has been pressed and track it. when I run the code the output produces a large number or a large negative number instead of 1 or 2. what am i doing wrong? code :

unsigned char pb1in = 9;             // for incoming serial data
unsigned char pb1value = 0;
int count = 0;
int count2 = 0;
void setup() {
  Serial.begin(9600);             // opens serial port, sets data rate to 9600 bps
  Serial.print("Start \n");       // let the user know the program is running
  pinMode(pb1in,INPUT);
}

void loop() {
  pb1value = digitalRead(pb1in);   //check status of pb1
  while(pb1value == 1)             //wait until pb1 is pushed, the while argument becomes false when the button is pushed and pb1value is zero
  {
    pb1value = digitalRead(pb1in); //update pb1 status
    count = count - 48;
    count2 = count ++; 
  }
  delay(10);
  Serial.print("PB1 has been pushed \n");
  Serial.print("The button has been pushed "); // printing amount of button pushes
  Serial.print(count2);
  Serial.print(" times \n");

  while(pb1value == 0)             //wait until pb1 is released, the while argument becomes false when the button is not pushed and pb1value is one
  {
    pb1value = digitalRead(pb1in); //update pb1 status
  }
  Serial.print("PB1 has been released \n");
  Serial.print(" \n");
  delay(10);
}

[jremington]

You probably should count when the button BECOMES pressed, rather than count during the entire time it IS pressed.

See the Arduino State Machine Example.

[LarryD]

Suggest you avoid using while( ) in your sketches.

If not used wisely, while( ) can block code execution which is almost always not what you need to do.

[Idahowalker]

@colin_coder

while(pb1value == 1)             //wait until pb1 is pushed, the while argument becomes false when the button is pushed and pb1value is zero
  {
    pb1value = digitalRead(pb1in); //update pb1 status
    count = count - 48;
    count2 = count ++; 
  }

As per the notes this while loop stays doing the things in the while loop till the button IS pressed.

Now looking at those things. One of them is count2 = count ++;. Making the count2 change, rapidly, during the time the button is not pressed. The source for large numbers and even -numbers from overflows.

[johnwasser]

@colin_coder

count = count - 48;

Why???

[SteveMann]

@colin_coder

the output produces a large number or a large negative number instead of 1 or 2

Because there is no debounce in your code and mechanical pushbuttons are very noisy. Loop is normally executed many thousands of times a second unless you have blocking code, like while or delay. If your switch is noisy, you will never get an accurate count without debouncing the button.

[JCA34F]

Which Arduino? Do you have a 10K pulldown resistor between pin 9 and GND?