Motion controlled light

Question

I'm trying to create an motion controlled light that doesn't turn on unless it's dark.

I want the light to turn on and off slowly with pwm when motion is detected. Right now my code works and does almost everything I want it to.

The problem is that I'm using the delay function to keep the light on after it reaches full brightness. And because of this if motion is detected while the light is on it doesn't reset the timer. Once the delay timer runs out and motion is detected the brightness will go down and then back up.

I would like to have the motion detector reset the timer that keeps the led on but haven't been able to get it working.

I have looked at these:

http://playground.arduino.cc/Code/AvoidDelay

https://www.arduino.cc/en/Tutorial/BlinkWithoutDelay

But because of my somewhat limited understanding of arduino code I haven't been able to get it working. I would really appreciate any help.

SOLVED

The working code below:

const byte MotionPin = 4; // Motionsensor
int LightSensorPin = 2; // Lightsensor
const byte LedPin = 11; // LED

unsigned long MotionDetectedMillis; // When motion was detected
unsigned long ledTurnedOnAt; // when led was turned on
unsigned long turnOnDelay = 50; // wait to turn on LED
unsigned long turnOffDelay = 5000; // turn off LED after this time
bool ledReady = false; // Has motion been detected
bool ledState = false; // Led on or off
int LightSensorState = 0;

int fadeAmount = 5;   // How much to fade in a loop 
byte brightness = 0; 

void setup() {
 pinMode(MotionPin, INPUT);
 pinMode(LightSensorPin, INPUT);
 pinMode(LedPin, OUTPUT);

 digitalWrite(LedPin, LOW);
}

void loop() {
 // get the time at the start of this loop()
 unsigned long currentMillis = millis(); 

 if (digitalRead(MotionPin) == HIGH && digitalRead(LightSensorPin)== HIGH) 
 {
  MotionDetectedMillis = millis();
  ledReady = true;
 }

 if (ledReady) 
 {
   if ((unsigned long)(currentMillis - MotionDetectedMillis) >= turnOnDelay) 
   {
      while (brightness < 255)
      {
        brightness = brightness + fadeAmount;
        analogWrite(LedPin, brightness);
        delay(30); 
      }

     // setup our next "state"
     ledState = true;
     // save when the LED turned on
     ledTurnedOnAt = currentMillis;
     ledReady = false;
   }
 }

 // see if we are watching for the time to turn off LED
 if (ledState) 
 {
   if ((unsigned long)(currentMillis - ledTurnedOnAt) >= turnOffDelay) 
   {    
     while (brightness >0)
      {
        brightness = brightness - fadeAmount;
        analogWrite(LedPin, brightness);
        delay(30); 
      }
     ledState = false;
   }
 }
}

Answer 1

what you want is a state machine; you have to keep track in the loop of which state you currently are and what is the condition to trigger next state; because your loop will execute an action only if something happen to trigger a new state, instead of using delay() you will use a 'waiting for timeout' state (remember to keep a way to know what is the next state).

If this confuses you, imagine each state as step in the instruction manual; turn on led 1, wait x, turn on led 1 a bit more, wait y, etc.. And because you have no more delay, before or after manage the "normal flow" of the state, you can add some special case like "if input 2 is high and current state is X or Y then set current state to Z".