Output Devices

OLED

An OLED (Organic Light-Emitting Diode) display is a visual output device that creates images by lighting up individual pixels made of organic compounds.

In the XIAO, these screens communicate via the I2C protocol (using only two pins: SDA and SCL), allowing to display text, icons, and basic animations with very little wiring.

Code

 
                    #include 
                    #include 
                    #include 

                    #define SCREEN_WIDTH 128 
                    #define SCREEN_HEIGHT 64 
                    #define OLED_RESET    -1 
                    #define SCREEN_ADDRESS 0x3C 

                    Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

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

                    // Initialize the OLED display with the I2C address
                    if(!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
                        Serial.println(F("SSD1306 allocation failed"));
                        for(;;); 
                    }

                    // Clear the internal buffer
                    display.clearDisplay(); 
                    }

                    void loop() {
                    // Clear the display buffer before drawing new content
                    display.clearDisplay();      

                    // Configure text properties: size and color
                    display.setTextSize(1);      
                    display.setTextColor(SSD1306_WHITE); 
                    
                    // Set position and print the first line of text
                    display.setCursor(12, 5);    
                    display.println("FAB ACADEMY 2026");

                    // Update text size and position for the second line
                    display.setCursor(12, 25);    
                    display.setTextSize(2);      
                    display.println("Hello, Im Selene!");

                    // Push the buffer data to the actual OLED hardware
                    display.display();           
                    
                    delay(3000);
                    }
                    

Results

DC Motor

A DC motor is an electromechanical device that converts direct current (DC) electrical energy into mechanical rotation.

For the DC motor control, I designed and built an H-bridge board using the TB67H451AFNG driver. Below are the schematic and the final board design:

I connected the input pins of the H-bridge to the output pins of the microcontroller board I designed in previous weeks. The output pins of the H-bridge were then connected directly to the DC motor terminals.

A critical step in this setup was ensuring a common ground (GND) across the entire system.

Code

 
                    // Pin definitions for the TB67H451FNG Driver
                    const int IN1 = D1; // Control pin 1 connected to D1
                    const int IN2 = D2; // Control pin 2 connected to D2

                    void setup() {
                    // Set both control pins as outputs
                    pinMode(IN1, OUTPUT);
                    pinMode(IN2, OUTPUT);
                    
                    // Start Serial communication to see the status
                    Serial.begin(115200);
                    while(!Serial); // Wait for the Serial Monitor to open
                    }

                    void loop() {
                    // --- 1. MOVE FORWARD ---
                    Serial.println("Direction: Forward");
                    digitalWrite(IN1, HIGH); // IN1 High and IN2 Low makes the motor spin
                    digitalWrite(IN2, LOW);
                    delay(2000);             // Keep spinning for 2 seconds

                    // --- 2. BRAKE (STOP SUDDENLY) ---
                    Serial.println("Action: Braking");
                    digitalWrite(IN1, HIGH); // Both pins HIGH acts as an electronic brake
                    digitalWrite(IN2, HIGH);
                    delay(1000);             // Wait 1 second

                    // --- 3. MOVE REVERSE ---
                    Serial.println("Direction: Reverse");
                    digitalWrite(IN1, LOW);  // Swapping the signals changes the direction
                    digitalWrite(IN2, HIGH);
                    delay(2000);             // Keep spinning for 2 seconds

                    // --- 4. COAST (STOP SLOWLY) ---
                    Serial.println("Action: Stop (Coast)");
                    digitalWrite(IN1, LOW);  // Both pins LOW cuts power to the motor
                    digitalWrite(IN2, LOW);
                    delay(2000);             // Wait 2 seconds before starting again
                    }
                    

Results

Vibration motor

A vibration motor is a compact output device used to provide haptic feedback through mechanical movement.

I designed a custom module to control the vibration motor using two essential components: a MOSFET and a Diode. This setup is necessary because the motor requires more power than a microcontroller pin can safely provide.

Code

 
                    // Pin definitions
                    const int micPin = D0;           // Microphone OUT connected to A0
                    const int modulePin = D5;        // Motor Module connected to D5
+
                    // Settings
                    const float threshold = 2.5;     // Noise limit (Voltage) to trigger the motor
                    const float voltiosReferencia = 3.3; 

                    void setup() {
                    analogReadResolution(12);      // 12-bit resolution for RP2350
                    pinMode(modulePin, OUTPUT);    // Set module pin as output
                    
                    digitalWrite(modulePin, LOW);  // Start with motor OFF
                    
                    Serial.begin(115200);
                    while(!Serial);
                    }

                    void loop() {
                    unsigned int sampleWindow = 50; // 50ms window to catch sound waves
                    unsigned int signalMax = 0;
                    unsigned int signalMin = 4095;

                    unsigned long startMillis = millis();

                    // Step 1: Record sound to find Peak-to-Peak amplitude
                    while (millis() - startMillis < sampleWindow) {
                        int sample = analogRead(micPin);
                        if (sample > signalMax) signalMax = sample;
                        if (sample < signalMin) signalMin = sample;
                    }

                    // Step 2: Calculate intensity and real voltage
                    int peakToPeak = signalMax - signalMin;
                    float volts = (peakToPeak * voltiosReferencia) / 4095.0;

                    Serial.print("Intensity: ");
                    Serial.print(peakToPeak);
                    Serial.print(" | Voltage: ");
                    Serial.println(volts);

                    // Step 3: Logic to activate the External Module
                    if (volts >= threshold) {
                        // If sound is LOUD: Turn ON the module
                        digitalWrite(ledPin, HIGH);
                        digitalWrite(modulePin, HIGH);
                        
                        Serial.println(">>> MOTOR MODULE ACTIVATED <<<");
                        delay(400); // Keep vibrating for 400ms
                    } 
                    else {
                        // If sound is QUIET: Turn OFF everything
                        digitalWrite(ledPin, LOW);
                        digitalWrite(modulePin, LOW);
                    }

                    delay(10); 
                    }
                    

Results