BLE ESP32. Bluetooth. Send. Receive. Arduino IDE. Multitouch

Juan_Antonio · May 19, 2020, 3:10pm

11.- App sends Bytes by WriteBytesWithResponse.

App sends list of Bytes as decimal numbers: 97,109,105,103,111 (ASCII: a,m,i,g,o)
ESP32 receives those bytes and converts them to binaries:
01100001
01101101
01101001
01100111
01101111
Return values as list.

// Juan Antonio Villalpando.
// http://kio4.com/arduino/160_Wemos_ESP32_BLE.htm

#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>

String valor;

#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.length() > 0) {
        valor = "";
        for (int i = 0; i < value.length(); i++){
          valor = valor + value[i];
        }
           Serial.println(valor);
            // Convert valor to bytes.
            for(int i=0; i<valor.length(); i++){
               char myChar = valor.charAt(i);
                for(int i=7; i>=0; i--){
                  byte bytes = bitRead(myChar,i);
                  Serial.print(bytes, BIN);
                }
                 Serial.println("");
            }
 
   pCharacteristic->setValue(valor.c_str()); // Return valor
      }
    }
};

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

  BLEDevice::init("MyESP32");
  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("Iniciado.");
  pService->start();

  BLEAdvertising *pAdvertising = pServer->getAdvertising();
  pAdvertising->start();
}

void loop() {
//
}

Check Serial Monitor:

This tutorial in Spanish.