Week 01

Assignment 01: LED Counter #

Create a circuit and Arduino code that does the following

Circuit #

• Connect two LEDs to your Arduino using a breadboard
• Connect one switch to your Arduino using a breadboard

Code #

1. Read a momentary switch being pressed
2. When the program starts, both LEDs are off
3. When the switch is pressed once, the first LED turns on
4. When the switch is pressed the second time, the second LED turns on (the first one should also still be on)
5. When the switch is pressed the third time, both LEDs turn off
6. Repeat this same cycle of LEDs turning on and off in sequence (off, one LED, two LEDs, off…)

Document your work on the course website that you created. Deadline: Thursday, October 31, 13:00

Tips #

Check the tutorials on Digital Input from here

Test your code and circuit for bugs. Does it still work if you do the following:

• How fast can you click? Does it respond even if you click very fast?
• Hold the button down for a long time, what happens?

Solutions #

Only check these if you get stuck and cannot solve this on your own. Or compare your solution to these. If you did it differently and it works, that is great! Please document your solution. The aim of this is not to see how well you can copy solutions and follow instructions but rather to help you think how to start solving specific tasks with electronics and code.

int ledPin1 = 10;
int ledPin2 = 9;
int btnPin = 2;
int btnState = 0;
int prevBtnState = 0;
int counter = 0;
void setup() {
  // put your setup code here, to run once:
  pinMode(ledPin1, OUTPUT);
  pinMode(ledPin2, OUTPUT);
  pinMode(btnPin, INPUT);
  Serial.begin(9600);
}

void loop() {
  // check the button
  btnState = digitalRead(btnPin);

  // check if the state is different from the previous loop
  if (btnState != prevBtnState) {
    if (btnState == HIGH) {
      // add one to the counter
      counter++;
      // check if the counter is too large
      if(counter>2){
        counter = 0;
      }
      Serial.println(counter);
    }
  }
  // store the current button state for the next loop
  prevBtnState = btnState;

  switch (counter) {
    case 0:
      digitalWrite(ledPin1, LOW);
      digitalWrite(ledPin2, LOW);
      break;
    case 1:
      digitalWrite(ledPin1, HIGH);
      digitalWrite(ledPin2, LOW);
      break;
    case 2:
      digitalWrite(ledPin1, HIGH);
      digitalWrite(ledPin2, HIGH);
      break;
  }

  // delay helps to prevent noise from the input signal
  // even better way to do this would be to implement debouncing:
  // https://www.arduino.cc/en/Tutorial/BuiltInExamples/Debounce
  delay(10);
}