This page provides resources for our soldering kit, “theDemonstrator“.


theDemonstrator Arduino Sketch

Here is the Arduino Nano sketch needed for theDemonstrator.
You can also download it from GitHub here.

To obtain the sketch below:

  1. Click “show source”
  2. Move your mouse over the sketch and click the icon with these brackets:”<>”
  3. Select all the text in the new window, you can then select all the text and copy and paste it to your Arduino IDE.
/*theDemonstrator LED sequencer
Intended to use with the Arduino Nano board.

V1.0 11/18/2022
by Brian P. Cox, FutureVision Research
Sketch is under Creative Commmons License Attribution-NonCommercial-ShareAlike 4.0 International
Circuit board design and theDemonstrator name copyright © Brian P. Cox and FutureVision Research, all rights reserved.

/* Declare constants
We declare Arduino pin numbers as constants so we can change them in one spot, instead of making the change throughout our code
const int FIRST_LED_PIN = 3, LAST_LED_PIN = 12; // Specifiy the first and last LED pins
const int MODE_BUTTONPIN = 2; // Specify the pin used for the button that will determine the sequencing mode. NOTE: Since pin 0 is used, do not press the mode button while programming the Arduino Micro via USB.
const int MODE_LED_PIN = 13; // Specify the pin used for the mode LED
const int ANALOG_SPEED_PIN = 0; // Specify the analog pin A0 for the voltage divider that will determine the sequencing speed
const int MIN_SPEED = 10; // Specify the minimum sequence speed in milliseconds
const int MAX_SPEED = 1000; // Specify the maximum sequence speed in milliseconds
const int MAX_MODES = 4; //Set the maximum number of modes we will rotate through (When this is set to zero, there is one mode)

// Declare variables
int voltageDivider = 0; //Used to store the result of the analog read from the voltage divider
int sequenceSpeed = MIN_SPEED; //Used to store the current sequencer interval in milliseconds
int modeButtonState = 0; //Used to store the result of button press. Button has pulldown resistor, so HIGH = button press
int counter; //used to keep track of counts in for loops
int currentMode = 1; //Used to keep track of the current mode for the LED sequencer
unsigned long lastInterruptTime = 0; //Used to keep track of time since the interrupt was last triggered

void setup() { //Setup function runs once
  Serial.begin(9600); //Set serial output to 9600 baud
  // Configure digital pins
  for (counter = FIRST_LED_PIN; counter &lt;= LAST_LED_PIN; counter++) {  //Set all LED pins as outputs
    delay(250); //Provides delay so we can see each pin change from float status to sink, which is the default mode for output
    } //End of counter
  // Configure settings for mode change button
  pinMode (MODE_BUTTONPIN, INPUT_PULLUP); //Set button pin as input and enable built in pull up resistor
  attachInterrupt(digitalPinToInterrupt(MODE_BUTTONPIN), modeChange, LOW); //Creates an Interrupt Service Routine that calles the function modeChange() each time the mode button is pressed.
} //End of setup function

void loop() { //Loop function runs over and over
  digitalWrite(MODE_LED_PIN, LOW); //Set MODE LED low in case there has been a mode change
  switch (currentMode){//Calls proper LED sequencer function based on the current mode
    case 1:
    case 2:
    case 3:
    case 4:
  }//End of switch
 }//End of loop function  

void modeChange(){ //Function called by Interrup Service Routine (ISR) to change the mode of the sequencer
 unsigned long interruptTime = millis(); //Reads the current time so it can be sued to debounce the mode button press
 if (interruptTime - lastInterruptTime &gt; 200) { //Used to debounce the mode button press
  currentMode = ++currentMode; //increase the mode count by 1
    if (currentMode &gt; MAX_MODES) {
      currentMode = 1;     
  digitalWrite(MODE_LED_PIN, HIGH); //Light mode LED to indicate a mode change has occured.
  Serial.print("Changed to mode: ");
  lastInterruptTime = interruptTime; //Keeps track of the last time the interrupt was triggered so it can be used to debounce the mode button press
} //End of modeChange function

void classicSequencer(){ //Lignt one LED at a time from left to right
  for (counter = FIRST_LED_PIN; counter &lt;= LAST_LED_PIN; ++counter) { //counter used to keep track of LED sequence
    digitalWrite(counter, HIGH);
    digitalWrite(counter, LOW);
    }//End of counter
}//End of classicSequencer function
void oneAfterAnother(){ //Light one LED after another then turn each one off
    for(counter = FIRST_LED_PIN; counter &lt;= LAST_LED_PIN; ++counter) { 
      digitalWrite(counter, HIGH);
    for(counter = LAST_LED_PIN; counter &gt;= FIRST_LED_PIN; --counter) {
      digitalWrite(counter, LOW);
}//End of oneAfterAnother function

void pingPong(){
  for(counter = FIRST_LED_PIN; counter &lt;= LAST_LED_PIN; ++counter) {//Light one LED at a time from left to right
    digitalWrite(counter, HIGH);  // turn LED on
    timeDelay(sequenceSpeed);                    // pause to slow down
    digitalWrite(counter, LOW);   // turn LED off

  for(counter = LAST_LED_PIN; counter &gt;= FIRST_LED_PIN; --counter) { //Light one LED at a time from right to left
    digitalWrite(counter, HIGH);  // turn LED on
    timeDelay(sequenceSpeed);                    // pause to slow down
    digitalWrite(counter, LOW);   // turn LED off
}//End of pingPong function

void randomLED(){
  counter = random(FIRST_LED_PIN,LAST_LED_PIN+1);  // pick a LED pin within the proper range
  digitalWrite(counter, HIGH);  // turn LED on
  timeDelay(sequenceSpeed);                    // pause to slow down
  digitalWrite(counter, LOW);   // turn LED off

int getSequenceSpeed(){//This function reads the value of the potentiometer and coverts it to a sequence speed range specified at the beginning of the sketch.
  sequenceSpeed = analogRead(ANALOG_SPEED_PIN); //Reads the value of the voltage divider and assigns it to the variable sequenceSpeed
  sequenceSpeed = map (sequenceSpeed, 0, 1024, MIN_SPEED, MAX_SPEED); //Converts the speed value to the range specified
  return sequenceSpeed;
}//End of getSequenceSpeed function

void timeDelay(int sequenceSpeed){//This function replaces the built-in Arduino function delay(). It provides a delay while still allowing interrupts to be triggered.
  unsigned long startMillis = millis();
  unsigned long currentMillis = millis(); 
  while (currentMillis - startMillis &lt;= sequenceSpeed){
    currentMillis = millis();
}//End of timeDelay function

This video provides full instructions on building theDemonstrator.
Use this video in combination with the printable instructions.