No Delay Blink for Multiple L.E.Ds

Blink.c

/* 
 * Author: WORMSS
 * 
 * Blink with no Delay
 * - This allows for multiple LEDs to be used.
 * - This allows for delayed start of sequence.
 * - This allows for different on and off delays.
 * 
 * Instructions:
 * - Change the LENGTH variable below with the amount of LEDs you wish to use.
 * - Within the setup() function play around with the mLights[] settings to change what you wish.
 * - mLights[0] refers to the first light. mLights[1] refers to the second light.
 * - 
 * - mLights[0].pin refers to the pin of the first LED.
 * - mLights[1].onInterval refers to the duration the second LED should stay on for.
 * - mLights[2].offInterval refers to the duration the third LED should stay off for.
 */


/* Amount of Lights to change */
const unsigned char LENGTH = 3;


/* 
 * This is the setup of the LightAction structure.
 * - This will be used to hold all the Lights individual settings
 */
typedef struct LightAction {
	/* The number of the Pin, max value 255 */
	unsigned char pin;
	
	// The state of the Light, either HIGH (on) or LOW (off)
	unsigned char state;
	
	// The time in milliseconds the next time the light needs to change state
	unsigned long nextTime;
	
	// The interval in milliseconds the light should stay off for.
	unsigned long offInterval;
	
	// The interval in milliseconds the light should stay on for.
	unsigned long onInterval;
} LightAction;

/* 
 * This is the array that holds all the of the lights in a second variable 
 * - If you are unfamiliar with arrays, I recommend a quick google search for "Arrays in C"
 */
LightAction mLights[LENGTH];

/* 
 * This will hold the current time for the device
 * - We set the time in this variable to save from calling millis() multiple times.
 */
unsigned long mCurrentTime;

void setup() {
	/* 
	 * This section is setting up each Light
	 * - The number within the brackets increases, This is the number of the light.
	 * - Note: we start with 0
	 * - This section you can add, remove, change these settings for your individual needs.
	 * - use nextTime to delay its start time.
	 */
	mLights[0].pin = 12;
	mLights[0].offInterval = 6000;
	mLights[0].onInterval = 10000;
	mLights[0].nextTime = 5000;

	mLights[1].pin = 7;
	mLights[1].offInterval = 3500;
	mLights[1].onInterval = 1000;

	mLights[2].pin = 2;
	mLights[2].offInterval = 12000;
	mLights[2].onInterval = 10000;
	
	/*
	 * No need to change anything from this point on
	 */
	
	// Loops through the lights and sets the pins to OUTPUT and turn on if state is HIGH
	for (unsigned int i = 0; i < LENGTH; i++) {
		pinMode(mLights[i].pin, OUTPUT);
		if ( mLights[i].state ) {
			digitalWrite(mLights[i].pin, HIGH);
		}
	}
}

// This function tests if the light needs to be changed yet
void processLightAction(LightAction *action) {
	if (mCurrentTime > action->nextTime) {
		/* 
		 * Flip the state from HIGH to LOW, or LOW to HIGH.
		 * This increments the number by 1, but if the number turns to 2 returns it to 0.
		 * The reason this works is because LOW is 0, and HIGH is 1.
		 */
		++action->state %= 2;
		
		/* 
		 * Set the time of when the next action needs to be triggered.
		 * If the state is HIGH increment the time by onInterval,
		 * otherwise increment the time by offInterval.
		 */
		action->nextTime += action->state ? action->onInterval : action->offInterval;
		
		// Set the pin to the state
		digitalWrite(action->pin, action->state);
	}
}

void loop() {
	/*
	 * Set mCurrentTime to the amount of milliseconds the device has been turned on.
	 * mCurrentTime will be used within processLightAction function.
	 */
	mCurrentTime = millis();
	
	// Loop through each Light and pass to the processLightAction function
	for (unsigned int i = 0; i < LENGTH; i++) {
		processLightAction(&mLights[i]);
	}
}