Connecting arduino to vehicle mirrors

Other Hardware Motors, Mechanics, Power and CNC
1

I am programming the Arduino Uno Rev3 to wait for a 12v signal from my vehicle when it goes into reverse. Then power the motor to control my passenger side mirror to move down for 3 seconds, then when it is taken out of reverse, power it back up . I have found a signal source for the reverse gear and the 12v power source for up and a different source for down. I am having difficulty figuring out the coding. This is what I have so far.

setup(){
pinmode(2,INPUT);//reverse gear
pinmode(3,OUTPUT);//mirror down
pinmode(4,OUTPUT);//mirror up
}

loop(){
if ((2) == HIGH){
  digitalWrite(3,HIGH);//control the mirror down for 3 seconds
  delay(3000);
  digitalWrite(3,LOW);
}
  
//having difficulty here
digitalWrite(4,HIGH);

I believe I have figured out how to put the mirror down, but I want the arduino to wait for the signal to power off again and then power pin 4 for 3 seconds to put the mirror back up.

Thanks for any help.
-Michael

2

You need to detect not the state of the input pin, you need to detect
a change in the state of the pin. Otherwise you'll continue to move
the mirror forever.

There are 3 relevant conditions: pin hasn't changed since you last looked,
pin has gone LOW->HIGH, pin has gone HIGH->LOW.

Two of those mean you do something with the mirror for 3 seconds,
the first means you don't do anything with the mirror.

So you need to remember what the pin was last time - a global variable
will do that.

3

Thank you, that definitely gave me a place to start

const int inputPin = 2;
const int outputDown = 3;
const int outputUp = 4;

int inputPinState = LOW;
int lastInputPinState = LOW;

void setup (){
  
  pinMode(inputPin, INPUT);
  pinMode(outputDown, OUTPUT);
  pinMode(outputUp, OUTPUT);
}


void loop(){
  inputPinState = digitalRead(inputPin);
  if (inputPinState != lastInputPinState){
    if (inputPinState == HIGH){
      //make outputDown HIGH for 3 seconds
      digitalWrite(outputDown, HIGH);
      delay(3000);
      digitalWrite(outputDown, LOW);
    }
    else {
      //make outputUP HIGH for 3 seconds
      digitalWrite(outputUp, HIGH);
      delay(3000);
      digitalWrite(outputUp, LOW);
    }
    lastInputPinState = inputPinState;
  }
}