Lab Session 1: Intro to microcontrollers programming

Estimated time: 1.5h (1 session)

1. Working with real hardware

1.1. Turn an LED ON and OFF

Connect an LED as follows:

Run the following program:

#include <M5Core2.h>
#define LED_PIN 14

void setup() {
  M5.begin(); // Initialize M5Core2
  pinMode(LED_PIN, OUTPUT);
}

void loop() {
  digitalWrite(LED_PIN, HIGH);
  delay(500);
  digitalWrite(LED_PIN, LOW);
  delay(500);
}

Question

• What does the #define do?
• What does the pinMode() function do?
• What does the digitalWrite() function do?

Question

Note that you had to include the #include <M5Core2.h> and the M5.begin(); // Initialize M5Core Why did you have to do that? what are these instructions for?

1.2. Additional exercises

1.2.1. Blink at a certain frequency

• Using the same circuit as in the previous exercise, write a script that Blinks the LED at a frequency of 10Hz.

  Question

  • For how long does the LED has to be ON or OFF in each cycle?

1.2.2. Blink and stop

• Using the same circuit as in the previous exercise, write a script that Blinks the LED at a frequency of 2Hz and stops the blinking after 5 seconds.

  Question

  • How many times does the LED blink?
  • What is the final state of the LED when the blink stops, does it remain ON or OFF?

  Tip

  You may need to use the for loop, or the if...else condition.

2. Working in Simulation

2.1. Turn an LED ON and OFF

Connect an LED as follows:

Run the following program:

#define LED_PIN 21
#define BUTTON_PIN 35

void setup() {
    pinMode(LED_PIN, OUTPUT);
    pinMode(BUTTON_PIN, INPUT_PULLUP);
}

void loop() {
    digitalWrite(LED_PIN, HIGH);
    delay(500);
    digitalWrite(LED_PIN, LOW);
    delay(500);
}

2.2. Control the LED state with a push button

• Implement the circuit shown in the following diagram and simulate a program that:

  • Turns the LED ON when the button is pressed.
  • Turns the LED OFF when the button is not pressed.

  Tip

  • Use the function digitalRead() to get the status of the button.
  • You may need to use the if...else condition.

  

  Warning

  When you place the button, don’t forget to deselect the bounce option to avoid bouncing issues.

  

  Question

  • What information is included in the diagram.json? Did it change with respect to the previous exercise?
  • Can you do the exercise without using the if...else condition? How?

2.3. Additional exercises

2.3.1. Blink

• Using the same circuit as in the previous exercise, write a script that Blinks the LED while the button is pushed.

  Tip

  You may need to use the millis() function.

2.3.2. Short press vs long press

• Using the same circuit as in the previous exercise, write a script that does the following:

  • Short press (< 500 ms): Toggle LED (if the LED is ON, turns it OFF, and viceversa).
  • Long press (≥ 500 ms): Blink LED.

  Tip

  You may need to use the millis() function, and the if...else condition.