Monday, 7 December 2009

Setting an alarm

My next step was to learn how to control an output based on my real time clock.

Baby steps...

To begin, i used the arduino examples and looked at using a potentiometer (analog input) to control an output; led. i set up this circuit.
This was a good example to follow. I needed to see the values of the potentiometer so i used a code from my real time clock and inserted it into the example;

Serial.begin(9600); //read value from sensor

void loop ()

Serial.pintin(name you have given); //show value in your COM

I could now turn the potentiometer and see the values change in relation to my blinking LED.

I then opened my real time clock file and started making adjustments, doing a 'save as' so not to muck up my original code.

baby step 2...

I opened another arduino example of using 'if else'. This code allows you to set an action to a variable, like my time.

My goal: to set a time for a red led to turn on, otherwise keep green led on.

if(minute == 1) { // == must be used to use an exact value! otherwise will not work!

digitalWrite(redPin, HIGH); //turn on red pin
digitalWrite(greenPin, LOW); //turn off green pin

else { //otherwise turn green led on
digitalWrite(redPin, LOW); //turn off red pin
digitalWrite(greenPin, HIGH); //turn on green pin

This was good but would not let me keep more than one minute on.

Baby step 3...

I removed my 'if, else' with 'case' again using an arduino example.

First thing i needed to do with my real time clock programme, was to define my constants for the red led to be on;

const int nameMin = value; // mine was minuteMin = 1: this sets the min value for red led to be on
const int minuteMax = 2; //sets max value for red led to be on.

in the 'void loop' section of the code, i added;

int range = map(minute, minuteMin, minuteMax, 0,2) //maps sensor range to four options.

switch (range) { //do something different depending on the range value.

case 0: //action when 1 min is reached

digitalWrite(redPin, HIGH); //turn on red pin
digitalWrite(greenPin, LOW); //turn off green pin

this allowed my leds to react to a duration i set.

I had completed my goal of controlling an output based on my time.

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