Question that Prompted this Tutorial:
How can I control an LED or other device via BLE with my Thunkable app.
Goal:
Create an app using an ESP 32 to turn on/off an LED.
Explanation:
Once you master this topic, you can expand the concept to larger applications such by switching out the LED for a relay and controlling a powered device in your home via BLE or even could be used to toggle a lever that opens up a secret compartment in your desk where you hid your best coding tips!
Types of Apps You Might Use This In:
- Hobby Apps
- Health Care Products
- Remote Monitoring Systems
- Alarm/Security Systems
- Educational Apps
Blocks / Components Used:
Buttons
Labels
BLE component
ESP32 (and related items)
Link to Template / Example:
ESP32 Code
#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>
const byte ledG = 33;
#define SERVICE_UUID "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"
class MyCallbacks: public BLECharacteristicCallbacks {
void onWrite(BLECharacteristic *pCharacteristic) {
std::string value = pCharacteristic->getValue();
if (value == "0") {
digitalWrite(ledG, HIGH);
}
else {
digitalWrite(ledG, LOW);
}
}
};
void setup() {
Serial.begin(115200);
pinMode(ledG, OUTPUT);
BLEDevice::init("Thunkable & esp32");
BLEServer *pServer = BLEDevice::createServer();
BLEService *pService = pServer->createService(SERVICE_UUID);
BLECharacteristic *pCharacteristic = pService->createCharacteristic(
CHARACTERISTIC_UUID,
BLECharacteristic::PROPERTY_READ |
BLECharacteristic::PROPERTY_WRITE
);
pCharacteristic->setCallbacks(new MyCallbacks());
pCharacteristic->setValue("Turn me on/off");
pService->start();
BLEAdvertising *pAdvertising = pServer->getAdvertising();
pAdvertising->start();
}
void loop() {
// put your main code here, to run repeatedly:
delay(2000);
}
that’s a 220 Ω resistor
