ISR and variable incrementing

[DaStee]

Hello there,

I have trouble using a simple button connected to a NodeMCU and an ISR to increment a simple variable. Here is the relevant code i use:

#define BTN 5

int selectedEffect = 0;

volatile int flag = 0;
int flagValue = 0;



void setup(void) {
 attachInterrupt (digitalPinToInterrupt (BTN), changeEffect, RISING); // pressed
  
}


void loop(void) {
  noInterrupts();
  flagValue = flag;
  interrupts();
   
if (flagValue == 1) {
      flag = 0;
      flagValue = 0;
      selectedEffect++;
      Serial.println(selectedEffect);
   }
   
  if(selectedEffect>18) { 
    selectedEffect=0;
  } 
  
  switch(selectedEffect) {
// CODE
  }
}

ICACHE_RAM_ATTR void changeEffect() {
  flag = 1;
}

Whenever i push the button the variable gets incremented several times.

Any idea?

[sterretje]

I guess that that is caused by bounce.

Your topic has been moved to a more suitable location on the forum. Installation and Troubleshooting is not for problems with (nor for advice on) your project.

[LarryD]

First off, suggest you wire switches as S3 is wired below.

---

Second, switches being monitored by interrupt logic will be a disaster.

Use poling of your switches (say every 50ms) and look for a switch change in state.

[groundFungus]

My active low state change tutorial may be of interest.

As shown in the tutorial, a 0.1uF ceramic cap across the switch will help to denounce the switch. It the is S3 of the schematic of @LarryD with a cap across the switch.

[DaStee]

Hello,

Thanks for your inputs.

I wired by switched with an external pull down (which i forgot to mention). Now i get this is bad

I'll try using the internal pullup, which i believe can be achived on all inputs but GPIO16 on NodeMCU (GPIO16 is using pulldown). I'll also add a cap and see if thats better.

Thanks

EDIT : i rewired using internal pullup and ceramic cap and modified the code consequently.

When i press the button only one increment, but when i release it i have one or two more increments. Also after a few presses the ESP hangs and resets.

[DaStee]

I finally resigned to using a simple polling in the loop function and it works fine for my need.

Thanks a lot

[groundFungus]

Really, using an interrupt for a human interface is not appropriate, anyway. Properly written non-blocking polling code will not miss button presses.