Week 12: Bluetooth LED Control

Assignment

Create a networking project using the ESP32C3

Project: Phone-Controlled LED

I created a simple Bluetooth project that lets me control an LED from my phone. When connected via Bluetooth, I can turn the LED on and off remotely.

Process

I used the Xiao ESP32C3 for this project because of its built-in Bluetooth capabilities (and also because this is what I was using for my FP) The steps were:

Set up the ESP32C3 with an LED
Write code for Bluetooth communication
Test using a BLE scanner app on my phone
Create a simple PCB for the final version

Code

Here's the code for the LED control:


#include 
#include 
#include 

#define LED_PIN 2
#define SERVICE_UUID        "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"

BLECharacteristic* characteristic;
bool deviceConnected = false;

class MyServerCallbacks : public BLEServerCallbacks {
    void onConnect(BLEServer* server) override {
        deviceConnected = true;
        Serial.println("Device connected!");
    }

    void onDisconnect(BLEServer* server) override {
        deviceConnected = false;
        Serial.println("Device disconnected!");
    }
};

void setup() {
    Serial.begin(115200);
    pinMode(LED_PIN, OUTPUT);
    
    BLEDevice::init("LED_Control");
    BLEServer* server = BLEDevice::createServer();
    server->setCallbacks(new MyServerCallbacks());
    
    BLEService* service = server->createService(SERVICE_UUID);
    characteristic = service->createCharacteristic(
        CHARACTERISTIC_UUID,
        BLECharacteristic::PROPERTY_READ | BLECharacteristic::PROPERTY_WRITE
    );
    
    service->start();
    BLEAdvertising* advertising = BLEDevice::getAdvertising();
    advertising->addServiceUUID(SERVICE_UUID);
    advertising->start();
}

void loop() {
    if (deviceConnected) {
        std::string value = characteristic->getValue();
        if (value == "ON") {
            digitalWrite(LED_PIN, HIGH);
        } else if (value == "OFF") {
            digitalWrite(LED_PIN, LOW);
        }
    }
    delay(20);
}

Challenges

Initially had trouble with the BLE library installation
Had to learn about UUID generation for BLE services
Needed to figure out the right pin for the LED on the ESP32C3
I did not get to producing a PCB for this one but did for my final project!

Files

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