UncaughtException: EPERM: operation not permitted about onoff

[fivdi]

What type of system is the error occurring on? A Raspberry Pi 0, 1, 2, 3 or 4? A BeagleBone? Something else?

If a Raspberry Pi with a 40-pin GPIO header is being used please ensure that the SPI1 peripheral is not activated for usage as activating SPI1 will reserve GPIO20 for SPI thus making it unusable for other purposes.

Please post a complete (but short) program that can be run and used to reproduce the error rather than snippets of code.

Please post the content of /boot/config.txt

[fivdi]

If GPIO20 is configured as an output and later configured as an input, calling writeSync for GPIO20 will result in an EPERM error. This is to be expected as it's not permitted to call writeSync for a GPIO configured as an input.

For example, running this program:

const Gpio = require('onoff').Gpio;

const relay2 = new Gpio(20, 'out');
const input = new Gpio(20, 'in');

function a() {
  relay2.writeSync(1);
}

a();

results in this EPERM error:

internal/fs/utils.js:259
    throw err;
    ^

Error: EPERM: operation not permitted, write
    at Object.writeSync (fs.js:694:3)
    at Gpio.writeSync (/home/pi/onoff/node_modules/onoff/onoff.js:243:8)
    at a (/home/pi/onoff/t.js:7:10)
    at Object.<anonymous> (/home/pi/onoff/t.js:10:1)
    at Module._compile (internal/modules/cjs/loader.js:1185:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1205:10)
    at Module.load (internal/modules/cjs/loader.js:1034:32)
    at Function.Module._load (internal/modules/cjs/loader.js:923:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)
    at internal/main/run_main_module.js:17:47 {
  errno: -1,
  syscall: 'write',
  code: 'EPERM'
}

Perhaps your program is configuring GPIO20 first as an output, then as an input and the calling writeSync

[fivdi]

@rajanlagah Any news on this one?

[rajanlagah]

I do have
var relay2 = new Gpio(20, 'out'); and then

function enable( ){
    if(stage == 1){
        relay2.writeSync(1);
    }
    if(stage == 2){
        liveD.writeSync(1);
    }
    if(stage == 3){
        relay2.writeSync(0);
    }
    if(stage == 4){
        liveD.writeSync(1);
    }
    if(stage < 4){
        setTimeout(enable(stage+1),500)
    }
}

As you can see i am performing only writeSync

[fivdi]

As mentioned above, please post a complete (but short) program that can be run and used to reproduce the error rather than snippets of code.

I'm afraid I can't provide any help without a complete (but short) program that can be used to reproduce the error.

Edit: This line of code is most likely not doing what you think it is doing:

        setTimeout(enable(stage+1),500)

[rajanlagah]

const LCD = require('lcdi2c');
var Gpio = require('onoff').Gpio; //include onoff to interact with the GPIO
var liveA = new Gpio(21, 'out');
var liveB = new Gpio(26, 'out');
var liveC = new Gpio(19, 'out');
var liveD = new Gpio(13, 'out');
var relay1 = new Gpio(16, 'out');
var relay2 = new Gpio(20, 'out'); 

function enable( ){
    if(stage == 1){
        relay2.writeSync(1);
    }
    if(stage == 2){
        liveD.writeSync(1);
    }
    if(stage == 3){
        relay2.writeSync(0);
    }
    if(stage == 4){
        liveD.writeSync(1);
    }
    if(stage < 4){
        setTimeout(enable(stage+1),500)
    }
}

enable()

This is my short code

[fivdi]

What is the output of that program when you run it?
Were is stage defined?

[rajanlagah]

var blinkInterval = "" // setInterval(blinkLED, 500); //run the blinkLED function every 250ms
var stepNumber = 0;

function blinkLED() { //function to start blinking
  if (stepNumber == 0) {

        relay2.writeSync(1);
    vending = true;
    console.log("Turned off card");
    stepNumber = 1;

  } else if(stepNumber == 1){

    relay2.writeSync(0);
    stepNumber = 2;
    console.log("Turned on card");
    endBlink();
  }
}

function endBlink() { //function to stop blinking

  clearInterval(blinkInterval); // Stop blink intervals

  relay2.writeSync(0);
  console.log("Completed routine");
}

setTimeout(endBlink, 1000*60*5);

function enable( ){
    blinkInterval = setInterval(blinkLED, 500);
}
enable()

Another way of doing that but having same issue

[rajanlagah]

What is the output of that program when you run it?
Were is stage defined?

Yes yes it was a global variable

later we did this
function enable( stage=1){

[fivdi]

What is the output of this program when you run it?

[rajanlagah]

internal/fs/utils.js:259
    throw err;
    ^

Error: EPERM: operation not permitted, write
    at Object.writeSync (fs.js:694:3)
    at Gpio.writeSync (/home/pi/onoff/node_modules/onoff/onoff.js:243:8)
    at a (/home/pi/onoff/t.js:7:10)
    at Object.<anonymous> (/home/pi/onoff/t.js:10:1)
    at Module._compile (internal/modules/cjs/loader.js:1185:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1205:10)
    at Module.load (internal/modules/cjs/loader.js:1034:32)
    at Function.Module._load (internal/modules/cjs/loader.js:923:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)
    at internal/main/run_main_module.js:17:47 {
  errno: -1,
  syscall: 'write',
  code: 'EPERM'
}

THIS

[fivdi]

That is not the output. That was copied that from here. I'm afraid I can't provide any further help, good luck.