continuous print of button Pushed

Question

When pushing a button I want to read the value...once. If I push(hold) the button I get a continuous print of button1Pushed

 if(button1State == LOW) { 
 Serial.println("button1Pushed");
 }

But if I try to solve it like this, nothing happens, not a single print. What am I missing?

 int button1State = digitalRead(button1);
 int lastButton1State;
 
 if(button1State != lastButton1State){
 if(button1State == LOW){
 Serial.println("button1Pushed");
 }
 }
 lastButton1State = button1State;

Answer 1

lastButton1State is not initialized and therefore has no strictly defined value. In your case, it appears to have a value of 0 (which is random, it's not due to implicit initialization, which is only done for global variables). The condition if(button1State != lastButton1State) becomes true only if the button is released.

You can check that by changing

if(button1State == LOW){
 Serial.println("button1Pushed");
}

to

if(button1State == HIGH){
 Serial.println("button1 released");
}

The following should work:

int last_button_state=HIGH; // initialize to HIGH, so the button does not teigger on very first iteration
void setup () {
 // whatever you want to do here
}
void loop() {
 int button_state=digitalRead(button1);
 if (button_state!=last_button_state && button_state==LOW) {
 Serial.println("button pressed");
 }
 else if (button_state!=last_button_state && button_state==HIGH) {
 Serial.println("button released");
 }
 last_button_state=button_state;
}

• Niles: your suggestion gives me the same result, still an endless repeat of the serial.print
• Sim Son: Did you see the change I made? I forgot to add last_button_state=button_state;... if it still doesn't work, please post the entire code
• Niles: I tried your suggestion in a blank sketch and it works! There is probably something buggy in the rest of my code (its pretty huge..for me..as a amateur)
• Niles: Found it! I put int last_button_state=HIGH; in the loop.....pff..time for bed
• Sim Son: @Niles please see my comment