Your design problem for this lab exercise consists of two parts. The first part

Question

Your design problem for this lab exercise consists of two parts. The first part involves the creation of three functions pinMode(), digitalWrite(), and digitalRead(). These functions are normally provided by the Arduino IDE. Your task is to write your own version of these functions that targets the Arduino UNO specifically. You can check the Arduino Language Reference to get an insight on what arguments these functions take and what they do. The second part of the design problem is to de-bounce a push button through software. Code has been provided for a non-de-bouncing solution. You must refer to the flowchart provided in the video lecture to implement two de-bouncing solutions. The first solution will use the _delay_ms() function, the second solution will use the millis() function. Finally, you will modify the circuit and the code in the second solution to use the pin’s internal pullup resistor. Check the provided Atmel Studio Project for more details

Explanation / Answer

2nd PART:

const int buttonPin = 2;   // the number of the pushbutton pin
const int ledPin = 13;   // the number of the LED pin

// Variables will change:
int ledState = HIGH;     // the current state of the output pin
int buttonState;     // the current reading from the input pin
int lastButtonState = LOW;   // the previous reading from the input pin

long lastDebounceTime = 0;  // the last time the output pin was toggled
long debounceDelay = 50;   // the debounce time; increase if the output flickers

void setup()

{
  pinMode(buttonPin, INPUT);
  pinMode(ledPin, OUTPUT);

  // set initial LED state
  digitalWrite(ledPin, ledState);
}

void loop() {
  // read the state of the switch into a local variable:
  int reading = digitalRead(buttonPin);

  // check to see if you just pressed the button
  // (i.e. the input went from LOW to HIGH), and you've waited
  // long enough since the last press to ignore any noise:

  // If the switch changed, due to noise or pressing:
  if (reading != lastButtonState) {
  // reset the debouncing timer
lastDebounceTime = millis();
  }

  if ((millis() - lastDebounceTime) > debounceDelay) {
  // whatever the reading is at, it's been there for longer
  // than the debounce delay, so take it as the actual current state:

  // if the button state has changed:
  if (reading != buttonState) {
buttonState = reading;

  // only toggle the LED if the new button state is HIGH
  if (buttonState == HIGH) {
ledState = !ledState;
  }
  }
  }

  // set the LED:
  digitalWrite(ledPin, ledState);

  // save the reading. Next time through the loop,
  // it'll be the lastButtonState:
lastButtonState = reading;
}

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