could not convert 'digitalWrite(8u, 1u)' from 'void' to 'bool'

Question

I am trying to make some LED lights to turn on when i flick a switch on my RC crontroller. I will connect the signal wire from RC controller to pin 8. The plan is: if i flick the swich, the LED's (pin 12,11,10,9) will turn on, and if i don't flick the swich the LED's wont turn on. This is a Arduino nano what will be connected on a drone.I found another question HERE, but there was no real answers. I get a error that say:

exit status 1 could not convert 'digitalWrite(8u, 1u)' from 'void' to 'bool'

How can i fix this? Should i write the code another way?

Arduino Code:

    void setup() {

  pinMode(4, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(11, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(8, INPUT);



}


void loop() {

  if (digitalWrite(8, HIGH));
    digitalWrite(12, HIGH);
    digitalWrite(11, HIGH);
    digitalWrite(10, HIGH);
    digitalWrite(9, HIGH); 
  else 
    digitalWrite(12, LOW);
    digitalWrite(11, LOW);
    digitalWrite(10, LOW);
    digitalWrite(9, LOW);

  digitalWrite(4,HIGH);
  delay(1500);
  digitalWrite(4,LOW);
}

Answer 1

You should be using digitalRead(8) instead of digitalWrite(8, HIGH). Your sketch is also missing some curly brackets.

void setup(){
  pinMode(4, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(11, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(8, INPUT);
}

void loop(){
  if(digitalRead(8) == HIGH){
    digitalWrite(12, HIGH);
    digitalWrite(11, HIGH);
    digitalWrite(10, HIGH);
    digitalWrite(9, HIGH);
  } 
  else{
    digitalWrite(12, LOW);
    digitalWrite(11, LOW);
    digitalWrite(10, LOW);
    digitalWrite(9, LOW);
  }
  digitalWrite(4,HIGH);
  delay(1500);
  digitalWrite(4,LOW);
}

The use of delay() will block the sketch from doing anything else, and should be replaced with a millis() timer. Have a look at the BlinkWithoutDelay example in the IDE.

Answer 2

This line of code is the source of your problem.

void loop() {

  if (digitalWrite(8, HIGH));

If expressions expect a boolean (true/false), but if you check the documentation for digitalWrite(), you’ll see it returns “Nothing” (i.e. void).

You need to use digitalRead() to check the current state of the pin.