The code for this exercise is found at http://ardx.org/src/circ/CIRC02-code.txt but I reproduce it here because this is my blog and I know where to find it. So there. (Thanks to the great folks who develop and freely post the Arduino Experimentation Kit Example Code for all the rest of us.
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* | Arduino Experimentation Kit Example Code |
* | CIRC-02 .: 8 LED Fun :. (Multiple LEDs) |
* ---------------------------------------------------------
*
* A few Simple LED animations
*
* For more information on this circuit http://tinyurl.com/d2hrud
*
*/
//LED Pin Variables
int ledPins[] = {2,3,4,5,6,7,8,9}; //An array to hold the pin each LED is connected to
//i.e. LED #0 is connected to pin 2, LED #1, 3 and so on
//to address an array use ledPins[0] this would equal 2
//and ledPins[7] would equal 9
/*
* setup() - this function runs once when you turn your Arduino on
* We the three control pins to outputs
*/
void setup()
{
//Set each pin connected to an LED to output mode (pulling high (on) or low (off)
for(int i = 0; i < 8; i++){ //this is a loop and will repeat eight times
pinMode(ledPins[i],OUTPUT); //we use this to set each LED pin to output
} //the code this replaces is below
/* (commented code will not run)
* these are the lines replaced by the for loop above they do exactly the
* same thing the one above just uses less typing
pinMode(ledPins[0],OUTPUT);
pinMode(ledPins[1],OUTPUT);
pinMode(ledPins[2],OUTPUT);
pinMode(ledPins[3],OUTPUT);
pinMode(ledPins[4],OUTPUT);
pinMode(ledPins[5],OUTPUT);
pinMode(ledPins[6],OUTPUT);
pinMode(ledPins[7],OUTPUT);
(end of commented code)*/
}
/*
* loop() - this function will start after setup finishes and then repeat
* we call a function called oneAfterAnother(). if you would like a different behaviour
* uncomment (delete the two slashes) one of the other lines
*/
void loop() // run over and over again
{
oneAfterAnotherNoLoop(); //this will turn on each LED one by one then turn each off
//oneAfterAnotherLoop(); //does the same as oneAfterAnotherNoLoop but with
//much less typing
//oneOnAtATime(); //this will turn one LED on then turn the next one
//on turning the
//former off (one LED will look like it is scrolling
//along the line
//inAndOut(); //lights the two middle LEDs then moves them out then back
//in again
}
/*
* oneAfterAnotherNoLoop() - Will light one LED then delay for delayTime then light
* the next LED until all LEDs are on it will then turn them off one after another
*
* this does it without using a loop which makes for a lot of typing.
* oneOnAtATimeLoop() does exactly the same thing with less typing
*/
void oneAfterAnotherNoLoop(){
int delayTime = 100; //the time (in milliseconds) to pause between LEDs
//make smaller for quicker switching and larger for slower
digitalWrite(ledPins[0], HIGH); //Turns on LED #0 (connected to pin 2 )
delay(delayTime); //waits delayTime milliseconds
digitalWrite(ledPins[1], HIGH); //Turns on LED #1 (connected to pin 3 )
delay(delayTime); //waits delayTime milliseconds
digitalWrite(ledPins[2], HIGH); //Turns on LED #2 (connected to pin 4 )
delay(delayTime); //waits delayTime milliseconds
digitalWrite(ledPins[3], HIGH); //Turns on LED #3 (connected to pin 5 )
delay(delayTime); //waits delayTime milliseconds
digitalWrite(ledPins[4], HIGH); //Turns on LED #4 (connected to pin 6 )
delay(delayTime); //waits delayTime milliseconds
digitalWrite(ledPins[5], HIGH); //Turns on LED #5 (connected to pin 7 )
delay(delayTime); //waits delayTime milliseconds
digitalWrite(ledPins[6], HIGH); //Turns on LED #6 (connected to pin 8 )
delay(delayTime); //waits delayTime milliseconds
digitalWrite(ledPins[7], HIGH); //Turns on LED #7 (connected to pin 9 )
delay(delayTime); //waits delayTime milliseconds
//Turns Each LED Off
digitalWrite(ledPins[7], LOW); //Turns on LED #0 (connected to pin 2 )
delay(delayTime); //waits delayTime milliseconds
digitalWrite(ledPins[6], LOW); //Turns on LED #1 (connected to pin 3 )
delay(delayTime); //waits delayTime milliseconds
digitalWrite(ledPins[5], LOW); //Turns on LED #2 (connected to pin 4 )
delay(delayTime); //waits delayTime milliseconds
digitalWrite(ledPins[4], LOW); //Turns on LED #3 (connected to pin 5 )
delay(delayTime); //waits delayTime milliseconds
digitalWrite(ledPins[3], LOW); //Turns on LED #4 (connected to pin 6 )
delay(delayTime); //waits delayTime milliseconds
digitalWrite(ledPins[2], LOW); //Turns on LED #5 (connected to pin 7 )
delay(delayTime); //waits delayTime milliseconds
digitalWrite(ledPins[1], LOW); //Turns on LED #6 (connected to pin 8 )
delay(delayTime); //waits delayTime milliseconds
digitalWrite(ledPins[0], LOW); //Turns on LED #7 (connected to pin 9 )
delay(delayTime); //waits delayTime milliseconds
}
/*
* oneAfterAnotherLoop() - Will light one LED then delay for delayTime then light
* the next LED until all LEDs are on it will then turn them off one after another
*
* this does it using a loop which makes for a lot less typing.
* than oneOnAtATimeNoLoop() does exactly the same thing with less typing
*/
void oneAfterAnotherLoop(){
int delayTime = 100; //the time (in milliseconds) to pause between LEDs
//make smaller for quicker switching and larger for slower
//Turn Each LED on one after another
for(int i = 0; i <= 7; i++){
digitalWrite(ledPins[i], HIGH); //Turns on LED #i each time this runs i
delay(delayTime); //gets one added to it so this will repeat
} //8 times the first time i will = 0 the final
//time i will equal 7;
//Turn Each LED off one after another
for(int i = 7; i >= 0; i--){ //same as above but rather than starting at 0 and counting up
//we start at seven and count down
digitalWrite(ledPins[i], LOW); //Turns off LED #i each time this runs i
delay(delayTime); //gets one subtracted from it so this will repeat
} //8 times the first time i will = 7 the final
//time it will equal 0
}
/*
* oneOnAtATime() - Will light one LED then the next turning off all the others
*/
void oneOnAtATime(){
int delayTime = 100; //the time (in milliseconds) to pause between LEDs
//make smaller for quicker switching and larger for slower
for(int i = 0; i <= 7; i++){
int offLED = i - 1; //Calculate which LED was turned on last time through
if(i == 0) { //for i = 1 to 7 this is i minus 1 (i.e. if i = 2 we will
offLED = 7; //turn on LED 2 and off LED 1)
} //however if i = 0 we don't want to turn of led -1 (doesn't exist)
//instead we turn off LED 7, (looping around)
digitalWrite(ledPins[i], HIGH); //turn on LED #i
digitalWrite(ledPins[offLED], LOW); //turn off the LED we turned on last time
delay(delayTime);
}
}
/*
* inAndOut() - This will turn on the two middle LEDs then the next two out
* making an in and out look
*/
void inAndOut(){
int delayTime = 100; //the time (in milliseconds) to pause between LEDs
//make smaller for quicker switching and larger for slower
//runs the LEDs out from the middle
for(int i = 0; i <= 3; i++){
int offLED = i - 1; //Calculate which LED was turned on last time through
if(i == 0) { //for i = 1 to 7 this is i minus 1 (i.e. if i = 2 we will
offLED = 3; //turn on LED 2 and off LED 1)
} //however if i = 0 we don't want to turn of led -1 (doesn't exist)
//instead we turn off LED 7, (looping around)
int onLED1 = 3 - i; //this is the first LED to go on ie. LED #3 when i = 0 and LED
//#0 when i = 3
int onLED2 = 4 + i; //this is the first LED to go on ie. LED #4 when i = 0 and LED
//#7 when i = 3
int offLED1 = 3 - offLED; //turns off the LED we turned on last time
int offLED2 = 4 + offLED; //turns off the LED we turned on last time
digitalWrite(ledPins[onLED1], HIGH);
digitalWrite(ledPins[onLED2], HIGH);
digitalWrite(ledPins[offLED1], LOW);
digitalWrite(ledPins[offLED2], LOW);
delay(delayTime);
}
//runs the LEDs into the middle
for(int i = 3; i >= 0; i--){
int offLED = i + 1; //Calculate which LED was turned on last time through
if(i == 3) { //for i = 1 to 7 this is i minus 1 (i.e. if i = 2 we will
offLED = 0; //turn on LED 2 and off LED 1)
} //however if i = 0 we don't want to turn of led -1 (doesn't exist)
//instead we turn off LED 7, (looping around)
int onLED1 = 3 - i; //this is the first LED to go on ie. LED #3 when i = 0 and LED
//#0 when i = 3
int onLED2 = 4 + i; //this is the first LED to go on ie. LED #4 when i = 0 and LED
//#7 when i = 3
int offLED1 = 3 - offLED; //turns off the LED we turned on last time
int offLED2 = 4 + offLED; //turns off the LED we turned on last time
digitalWrite(ledPins[onLED1], HIGH);
digitalWrite(ledPins[onLED2], HIGH);
digitalWrite(ledPins[offLED1], LOW);
digitalWrite(ledPins[offLED2], LOW);
delay(delayTime);
}
}
This exercise is meant to teach us about for() loops (used when you want to run a piece of code several times)and arrays[], used to make managing variables easier (an array is a group of variables).
I built the board up with the 8 LEDs and 8 resistors using pattern 2, but by mistake I used 10K ohm resitors for all the pins except pin 8, even though the pattern said to use 330 ohm resistors. I wasn't paying attention -- the kit comes with two little bags of resistors, one of them 330 Ohm and the other 10 KOhm. Then I noticed when I compiled the code to the board that all the LEDs were lighting dimly except the one with the 330 ohm resistor which lit at full brightness. Duh.
No matter, it still works. The exercise here is to explore different ways of writing in the loop function.
There are four examples; the first and second do the same thing but the second, "oneAfterAnotherLoop" uses much less writing. The use of "for loops" is the key here.
The manual invites you to comment and uncomment the four different options and see what they do;
It is clear from this example that one can put the definitions of the behaviors (i.e. the code for
oneAfterAnotherNoLoop(); oneAfterAnotherLoop(); oneOnAtATime(); and inAndOut(); ) AFTER the void setup() and void loop () codes.
The manual then invites us to "jump into the inluded code and start changing things. The main point is to turn an LED on use digitalWrite(pinNumber, LOW);. Type away, regardless of what you change you won't break anything."
That is comforting, so I decided to uncomment all 4 routines and see what happens.
What was cool was that when I did that all four behaviors ran in sequence.
So I then felt empowered and decided to put a delay of 5 seconds in between each behavior call to see what would happen (at first I left out the semicolon but the compiler alerted me that it was expecting a ";" so I wentback and added them. The code looks like this:
void loop() // run over and over again
{
oneAfterAnotherNoLoop(); //this will turn on each LED one by one then turn each off
delay(5000);
oneAfterAnotherLoop(); //does the same as oneAfterAnotherNoLoop but with
delay(5000); //much less typing
oneOnAtATime(); //this will turn one LED on then turn the next one
//on turning the
delay(5000); //former off (one LED will look like it is scrolling
//along the line
inAndOut(); //lights the two middle LEDs then moves them out then back
delay(5000); //in again
}
When I compiled it and ran it it did exactly as I predicted. So now I feel like a "code hacker" and that tiny experience with success encourages me to go on. I'm thinking, "maybe this isn't so hard after all."
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