I decided to make my own example code for writing functions as it should be one of the basic examples in Arduino. Yes, there is documentation on using a function, but one has to visit the Arduino website to try to use context and they don’t expand on their examples very well. I will split up this post with the starting code for an example without any functions, convert the same program using a function, show an extended example of what one can do with functions, and compare to a version of that code without functions to show that fewer lines of code can make it easier to use. Note that this example assumes that some of the fundamental Arduino examples are already known.
Starting Code With No Functions
/*
* This code is the starting code for my functionExample, I want to turn pins 13, 12, 11 high; wait for half a second; turn all the pins off; wait for half a second;
* and turn pins 13 and 11 on while keeping 12 off and wait for another half second.
*/
void setup() {
pinMode(13, OUTPUT);
pinMode(12, OUTPUT);
pinMode(11, OUTPUT);
}
boolean writePin = HIGH; //set a global variable to make it easier to turn things on and off in the function, use !writePin for LOW
void loop() {
//first, let's see how cumbersome writing code can be when trying to run several LEDs
//write all output pins high:
digitalWrite(13, writePin);
digitalWrite(12, writePin);
digitalWrite(11, writePin);
delay(500); //delay half a second
//write all pins low
digitalWrite(13, !writePin);
digitalWrite(12, !writePin);
digitalWrite(11, !writePin);
delay(500); //delay half a second
//write 13 and 11 high, keep 12 low
digitalWrite(13, writePin);
digitalWrite(12, !writePin);
digitalWrite(11, writePin);
delay(500);//delay half a second
//doing that sequence alone takes 12 lines of code to accomplish something that could probably be done in less
}
// 20 lines of code not including commentsI typically count significant lines of code that include the {}, but not the comments because the comments are ignored in the compiler anyway. This code feels clunky and there are a lot of repeated lines and you have to change several lines if a different action is desired. This is not a very efficient process when troubleshooting or making more complicated programs.
Starting Code Re-Made With a Function
/*
The Arduino home page does
try to explain funcitons using a math example and reading an analog pin, which is cool, but there are more things one can
do with functions. The anatomy of a function in Arduino is as follows:
dataType variableName(dataType parameterVariable1, dataType parameterVariable2, ...){}
All functions have to have a valid Arduino dataType at the beginning of the line of code because we use a variable to reference the entire code that will be run between the {}
If you want numbers or some sort of result with measurable values, you will have to use a data type that can store those values; examples are
int, double, unsigned long, long, boolean, float (and all the other types that can store data)
The only thing to mention is that functions with these dataTypes must have a return statement; Example:
int addTwoNumb(int one, int two){
int result = one + two;
return result;
}
The function above returns the calculation of one and two and can be stored in a new variable when called/used in the main loop.
The values inside the () are called parameters, functions don't always require parameters (most do though), so the () can be empty.
Parameters are placeholder variables with any data type valid in Arduino. These variables do not have to be assigned values until the function is used/called in the main loop, values are passed as soon as they are called. Any number of new variables can be added into a function and any amount of code can be added to a function, even functions can call other functions! (gets a little confusing at that point)
*/
void setup() {
pinMode(13, OUTPUT);
pinMode(12, OUTPUT);
pinMode(11, OUTPUT);
}
boolean writePin = HIGH; //set a global variable to make it easier to turn things on and off in the function, use !writePin for LOW
void loop() {
sequenceLights(13, 12, 11, writePin, writePin, writePin, 500); //call/use sequence lights on pins 13, 12, 11; use the default value for writePin (HIGH), delay for half a second (500 mS)
sequenceLights(13, 12, 11, !writePin, !writePin, !writePin, 500);
sequenceLights(13, 12, 11, writePin, !writePin, writePin, 500);
}
/* Functions are typically defined or written below the loop statement for clarity*/
//notice that the function below uses the exact same code but uses different variables and that we don't use a datatype (void), we aren't calculating anything, so there doesn't need to be a datatype
//the function takes 3 integers to begin with: pin13, pin12, pin11; these represent the values for the pins we want to control
//then the next three values are writeFunc1, writeFunc2, writeFunc3 which are boolean values used to control the pins (HIGH or LOW), we want to be able to use unique instructions per light as that is how the original sequence worked
//finaly delayPeriod is used in place of 500, because what if we want to change the timing, why not?
void sequenceLights(int pin13, int pin12, int pin11, boolean writeFunc1, boolean writeFunc2, boolean writeFunc3, int delayPeriod){
digitalWrite(pin13, writeFunc1);
digitalWrite(pin12, writeFunc2);
digitalWrite(pin11, writeFunc3);
delay(delayPeriod);
}
//17 lines of code not including commentsEven though the whole code was only reduced by 3 lines, this makes it easier to quickly adjust values if one desires to experiment with values for delay and whether a pin goes HIGH or LOW. If there wasn’t a function, this would have to be manually added with four lines of code each time.
Initial Code Wiring Diagram
Expanded Code Using Functions
void setup() {
//Serial.begin(9600); //I often use the serial monitor to debug my program or to do some testing, I then comment the line of code to increase some runtime speed (counted this line of commented code as it was essential to my process)
pinMode(13, OUTPUT);
pinMode(12, OUTPUT);
pinMode(11, OUTPUT);
pinMode(10, OUTPUT);
pinMode(9, OUTPUT);
pinMode(8, OUTPUT);
}
int countRndSeq = 0; //set initial variable for counting variable for the random sequence to "reset"
int randPin = random(8, 14); //set the random Pin variable to a random number between 8 and 13 (14 for including 13 as a choice); we only need 8-13 as those are the pins I use
void loop() {
randSequenceLightSlow(5, 125, 1200); //run function for a random sequence, set counting interval at 5, set minimum delay at 125, set the max delay to 1200 (1.2 seconds) (I decided to move the randMode into the function because it was easier to accomplish)
countRndSeq = 0; //reset the counter for the next sequence
delay(3000); //wait three seconds then turn off all the lights (made a function for that)
allPinsWrite(13, 12, 11, 10, 9, 8 , LOW);
randSequenceLightSlow(7, 125, 1450); //run function for random sequence using counting interval at 7, minimum delay at 125, set max delay to 1450 (1.450 seconds)
countRndSeq = 0; //reset counter for next sequence
delay(3000); //wait three seconds and turn off all the lights
allPinsWrite(13, 12, 11, 10, 9, 8, LOW);
}
/*
* The following uses a while loop for control, it does random lights and slows down delay by a set interval between steps (larger interval will make it count and slow down much quicker)
* As long as that counting number (countRndSeq) is less than the max delay (maxDel), it will do the following in order:
* 1. chose a random pin 8-13 and set it equal to a variable
* 2. Pick the random Mode value each time the while loop runs again (increases chance to get modes 0-2)
* 2. turn off the pin associated to that number using the delay amount of the same number that countrRndSeq is currently at
* 3. Increase countRndSeq by the interval amount set by calling the function (can be any integer)
* 4. Check if the current count is greater than the minimum delay and then check which mode (remember I set it to random above); there are 3 modes 0, 1, 2
* NOTE: For #4, 0 has a high chance of adding less to countRndSeq, 1 has a medium chance of adding a bit more to countRndSeq, 2 has a low chance of adding quite a bit to countRndSeq
* 5. Set the final pin after the sequence has finished to high to simulate that is the final pin the program landed on
* See calcThreshChance for an explanation of how I made weighted random events for the chance for the lights to slow faster
*/
void randSequenceLightSlow(int interval, int minDel, int maxDel){
while(countRndSeq < maxDel){
randPin = random(8, 14);
int mode = random(0, 3);
digitalWrite(randPin, HIGH);
delay(countRndSeq);
digitalWrite(randPin, LOW);
delay(countRndSeq);
countRndSeq += interval;
if(countRndSeq > minDel && mode == 0){
countRndSeq += calcThreshChance(mode, interval);
} else if(countRndSeq > minDel && mode == 1){
countRndSeq += calcThreshChance(mode, interval);
} else if(countRndSeq > minDel && mode == 2){
countRndSeq += calcThreshChance(mode, interval);
}
}
digitalWrite(randPin, HIGH);
}
/*
* Simple function that uses integers 8-13 and a boolean value to turn on or off all the LEDs at once
*/
void allPinsWrite(int p1, int p2, int p3, int p4, int p5, int p6, boolean writeInst){
digitalWrite(p1, writeInst);
digitalWrite(p2, writeInst);
digitalWrite(p3, writeInst);
digitalWrite(p4, writeInst);
digitalWrite(p5, writeInst);
digitalWrite(p6, writeInst);
}
/*
* The following function takes an integer 0-2 and calculates the chance for it to add more to the number countRndSeq
* First it sets up three variables local to the function (chance for around 50, a chance for around 200, and a chance for around 300)
* Then the following first check is made: check which mode is selected, 0, 1, or 2 (if someone entered something else or not calculated it will return 0 and count by the regular interval in the randomSequence)
* If it is mode 0, use a relatively short random range from 45 to 69 and check if that random number falls between 50 and 60 which is a pretty high chance based on the short range, so it will more than likely add 1000 plus that random number to countRndSeq
* If it is mode 1, use a larger range from 200 to 299 and check if that random number lies between 250 and 255, which is a medium chance, so it may or may not use that random number + 2000
* If it is mode 2, use a much larger range from 300 to 599 and check if that random number lies between 320 and 324, which is a low chance, so it has less likelihood of using that random number and adding 3000
* All other cases it will just add the regular interval
*/
int calcThreshChance(int mode, int interval){
int randCh50 = 0;
int randCh200 = 0;
int randCh300 = 0;
if(mode == 0){
randCh50 = random(45, 70);
if(randCh50 >= 50 && randCh50 <= 60){
return randCh50 + 1000;
} else {
return interval;
}
} else if (mode == 1){
randCh200 = random(200, 300);
if(randCh200 >= 250 && randCh200 <= 255){
return randCh200 + 2000;
} else {
return interval;
}
} else if (mode == 2){
randCh300 = random(300, 600);
if(randCh300 >= 320 && randCh300 <= 324){
return randCh300 + 3000;
} else {
return interval;
}
} else {
return interval;
}
}
//77 lines of code not including commentsThe idea of the code is to somewhat simulate a roll of a six-sided dice that rolls itself by starting fast and gradually slowing down to a final light. The code uses the built-in random function which uses a starting number (included in the generation) and an ending number that is excluded in the generation. Not only does it randomize the pins (8-13), but it also randomizes the chance for it to slow down significantly as some dice rolls do. I accomplished this with three “modes” of chance: A high chance to add less to the counting variable, a medium chance to add a little more to the counting variable, and a low chance to add a lot to the counting variable (see comments in the code for full context). There are three custom functions that I built to make this idea easier to understand and experiment with.
Expanded Code Without Custom Functions
void setup() {
pinMode(13, OUTPUT);
pinMode(12, OUTPUT);
pinMode(11, OUTPUT);
pinMode(10, OUTPUT);
pinMode(9, OUTPUT);
pinMode(8, OUTPUT);
}
int countRndSeq = 0;
int randPin = random(8,14);
int minDel1 = 125;
int maxDel1 = 1200;
int interval1 = 5;
int minDel2 = 125;
int maxDel2 = 1450;
int interval2 = 7;
int randCh50 = 0;
int randCh200 = 0;
int randCh300 = 0;
void loop() {
while(countRndSeq < maxDel1){
randPin = random(8, 14);
int randMode = random(0, 3);
digitalWrite(randPin, HIGH);
delay(countRndSeq);
digitalWrite(randPin, LOW);
delay(countRndSeq);
countRndSeq += interval1;
if(countRndSeq > minDel1 && randMode == 0){
randCh50 = random(45, 70);
if(randCh50 >= 50 && randCh50 <= 60){
countRndSeq += randCh50 + 1000;
} else {
countRndSeq += interval1;
}
} else if(countRndSeq > minDel1 && randMode == 1){
randCh200 = random(200, 300);
if(randCh200 >= 250 && randCh200 <= 255){
countRndSeq += randCh200 + 2000;
} else {
countRndSeq += interval1;
}
} else if(countRndSeq > minDel1 && randMode == 2){
randCh200 = random(300, 600);
if(randCh200 >= 320 && randCh200 <= 324){
countRndSeq += randCh200 + 3000;
} else {
countRndSeq += interval1;
}
} else {
countRndSeq += interval1;
}
}
digitalWrite(randPin, HIGH);
countRndSeq = 0;
delay(3000);
digitalWrite(13, LOW);
digitalWrite(12, LOW);
digitalWrite(11, LOW);
digitalWrite(10, LOW);
digitalWrite(9, LOW);
digitalWrite(8, LOW);
while(countRndSeq < maxDel2){
randPin = random(8, 14);
int randMode = random(0, 3);
digitalWrite(randPin, HIGH);
delay(countRndSeq);
digitalWrite(randPin, LOW);
delay(countRndSeq);
countRndSeq += interval2;
if(countRndSeq > minDel2 && randMode == 0){
randCh50 = random(45, 70);
if(randCh50 >= 50 && randCh50 <= 60){
countRndSeq += randCh50 + 1000;
} else {
countRndSeq += interval2;
}
} else if(countRndSeq > minDel2 && randMode == 1){
randCh200 = random(200, 300);
if(randCh200 >= 250 && randCh200 <= 255){
countRndSeq += randCh200 + 2000;
} else {
countRndSeq += interval2;
}
} else if(countRndSeq > minDel2 && randMode == 2){
randCh200 = random(300, 600);
if(randCh200 >= 320 && randCh200 <= 324){
countRndSeq += randCh200 + 3000;
} else {
countRndSeq += interval2;
}
} else {
countRndSeq += interval2;
}
}
digitalWrite(randPin, HIGH);
countRndSeq = 0;
delay(3000);
digitalWrite(13, LOW);
digitalWrite(12, LOW);
digitalWrite(11, LOW);
digitalWrite(10, LOW);
digitalWrite(9, LOW);
digitalWrite(8, LOW);
}
//105 lines of code not including commentsNotice this is significantly more lines to do the same thing (the function version has 28 lines less, which is significant when building larger programs). Not only is it less lines, but the way I used the functions made it significantly easier to experiment with different values. The handcoded version requires several variables to change on lines for experimentation. Imagine if one wanted to change the code for each desired action if there were more experiments to be done: a function allows one block of code to be edited to test out functionality quicker.
Expanded Code Wiring Diagram
Bill of Materials
Here is the link for the full cart of all the parts I used.
https://www.digikey.com/short/p8nzdq