Week 4 - Embedded Programming

I physically programmed my ESP-32S, with my already installed Arduino IDE installed on my system, as this is not my first rodeo, but I’ll walk you through the setup stage and let’s experience it again together.

Hardware Requirements

• ESP32S Development Board
• Micro USB cable
• Computer with Arduino IDE installed

Arduino IDE Configuration

Step 1: Open Arduino

Since I had Arduino already installed on my system, I clicked the Windows start menu and typed "Arduino" to access it. Arduino can also be installed from their website: https://www.arduino.cc/en/software

Step 2: Access Preferences

See below the default screen or sketch you would see on Arduino IDE, then go to File > Preferences:

Step 3: Additional board manager

Add ESP32 board URL in the “Additional boards manager URLs” (you can obtain the URL by searching on Arduino page for the GitHub link): https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json

Step 4: ESP-32 Board Support

Install ESP32 board support via Tools > Board > Boards Manager:

Step 5: ESP-32 Dev Module

Select "ESP32 Dev Module" from Tools > Board:

Basic Program Structure

void setup() {
    // Initialization code
    // Runs once at startup
}

void loop() {
    // Main program code
    // Runs repeatedly
}
        

GPIO Operations - Digital I/O Exploration

I explored programming the LED on the board with the following program. This program is a modification of the LED blinking code given to us by Toni (my local instructor). This program will:

• Slowly fade the LED in
• Hold at full brightness briefly
• Do three quick flashes
• Slowly fade out
• Pause in darkness before starting again

// Pin definitions
#define LED_PIN 2    // Onboard LED
#define BUTTON_PIN 0 // Boot button

void setup() {
    pinMode(LED_PIN, OUTPUT);
    ledcSetup(0, 5000, 8);  // Channel 0, 5KHz, 8-bit resolution
    ledcAttachPin(LED_PIN, 0);  // Attach LED pin to channel 0
}

void loop() {
    // Dramatic fade in
    for(int i = 0; i < 255; i++) {
        ledcWrite(0, i);
        delay(5);  // Slow, dramatic rise
    }
    delay(200);  // Dramatic pause at peak brightness
    
    // Quick flash sequence
    for(int j = 0; j < 3; j++) {
        ledcWrite(0, 0);
        delay(50);
        ledcWrite(0, 255);
        delay(50);
    }
    
    // Dramatic fade out
    for(int i = 255; i >= 0; i--) {
        ledcWrite(0, i);
        delay(10);  // Slower, more dramatic fall
    }
    
    delay(500);  // Dramatic pause in darkness
}
        

Other operations observed from the ESP-32S:

• Analog Operations
• Serial Communication
• Wi-Fi Connectivity
• Basic Wi-Fi Client
• Timer and Interrupt Handling

Summer 2024 Humidity and Temperature IoT Project in Super FabLab Oulu

An example of WiFi implementation in a microcontroller was done during my summer internship at FabLab Oulu, where we (interns) designed an ioT freashers course at the University of Oulu, on “measurement of humidity and temperature” using the DHT22 and the PICO-W. See code snippet below:

#include 
#define DHTPIN 14
#define DHTTYPE DHT22
DHT dht(DHTPIN, DHTTYPE);

void setup() {
    Serial.begin(115200);
    dht.begin();
}

void loop() {
    delay(2000);
    float temperature = dht.readTemperature();
    float humidity = dht.readHumidity();
    
    if (isnan(humidity) || isnan(temperature)) {
        Serial.println("Failed to read from the sensor");
        return;
    }
    
    Serial.print("Temperature: ");
    Serial.print(temperature);
    Serial.print("°C ");
    Serial.println();
    
    Serial.print("Humidity: ");
    Serial.print(humidity);
    Serial.print("g/kg ");
    Serial.println();
}