library/Arduino/BLE_uart_coderacer/BLE_uart_coderacer.ino

#include <CodeRacer.h>

/*
    Video: https://www.youtube.com/watch?v=oCMOYS71NIU
    Based on Neil Kolban example for IDF: https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleNotify.cpp
    Ported to Arduino ESP32 by Evandro Copercini

   Create a BLE server that, once we receive a connection, will send periodic notifications.
   The service advertises itself as: 6E400001-B5A3-F393-E0A9-E50E24DCCA9E
   Has a characteristic of: 6E400002-B5A3-F393-E0A9-E50E24DCCA9E - used for receiving data with "WRITE" 
   Has a characteristic of: 6E400003-B5A3-F393-E0A9-E50E24DCCA9E - used to send data with  "NOTIFY"

   The design of creating the BLE server is:
   1. Create a BLE Server
   2. Create a BLE Service
   3. Create a BLE Characteristic on the Service
   4. Create a BLE Descriptor on the characteristic
   5. Start the service.
   6. Start advertising.

   In this example rxValue is the data received (only accessible inside that function).
   And txValue is the data to be sent, in this example just a byte incremented every second. 
*/
#include <BLEDevice.h>
#include <BLEServer.h>
#include <BLEUtils.h>
#include <BLE2902.h>


#define LED_VORWAERTS 26          // Pin an dem die VORWÄRTS LED angeschlossen ist. 'GPIO' muss man weglassen -> also z.B. nicht GPIO88 sondern nur 88.
#define LED_STOP 25               // Pin an dem die STOP LED angeschlossen ist. 'GPIO' muss man weglassen -> also z.B. nicht GPIO88 sondern nur 88.
#define LED_LINKS 27              // Pin an dem die LINKS LED angeschlossen ist. 'GPIO' muss man weglassen -> also z.B. nicht GPIO88 sondern nur 88.
#define LED_RECHTS 33

BLECharacteristic *pCharacteristic;
bool deviceConnected = false;
uint8_t txValue = 0;
char CRstatus = 0;

// See the following for generating UUIDs:
// https://www.uuidgenerator.net/

#define SERVICE_UUID           "6E400001-B5A3-F393-E0A9-E50E24DCCA9E" // UART service UUID
#define CHARACTERISTIC_UUID_RX "6E400002-B5A3-F393-E0A9-E50E24DCCA9E"
#define CHARACTERISTIC_UUID_TX "6E400003-B5A3-F393-E0A9-E50E24DCCA9E"


class MyServerCallbacks: public BLEServerCallbacks {
    void onConnect(BLEServer* pServer) {
      deviceConnected = true;
    };

    void onDisconnect(BLEServer* pServer) {
      deviceConnected = false;
    }
};

class MyCallbacks: public BLECharacteristicCallbacks {
    void onWrite(BLECharacteristic *pCharacteristic) {
      std::string rxValue = pCharacteristic->getValue();

      if (rxValue.length() > 0) {
        Serial.println("*********");
        Serial.print("Received Value: ");
        for (int i = 0; i < rxValue.length(); i++)
          {
            
            CRstatus = rxValue[i];
            Serial.print(CRstatus);
            
          };

        Serial.println();
        Serial.println("*********");
      }
    }
};


void setup() {
  Serial.begin(115200);
  pinMode(LED_VORWAERTS, OUTPUT);     // LED Vorwärts ist ein Ausgang
  pinMode(LED_STOP, OUTPUT);          // LED Stop ist ein Ausgang
  pinMode(LED_LINKS, OUTPUT);         // LED Links ist ein Ausgang
  pinMode(LED_RECHTS, OUTPUT);        // LED Rechts ist ein Ausgang
                                        // alle LEDS aus
  digitalWrite(LED_VORWAERTS, LOW);
  digitalWrite(LED_STOP, LOW);
  digitalWrite(LED_LINKS, LOW);
  digitalWrite(LED_RECHTS, LOW);
  // Create the BLE Device
  BLEDevice::init("UART Service");

  // Create the BLE Server
  BLEServer *pServer = BLEDevice::createServer();
  pServer->setCallbacks(new MyServerCallbacks());

  // Create the BLE Service
  BLEService *pService = pServer->createService(SERVICE_UUID);

  // Create a BLE Characteristic
  pCharacteristic = pService->createCharacteristic(
                      CHARACTERISTIC_UUID_TX,
                      BLECharacteristic::PROPERTY_NOTIFY
                    );
                      
  pCharacteristic->addDescriptor(new BLE2902());

  BLECharacteristic *pCharacteristic = pService->createCharacteristic(
                                         CHARACTERISTIC_UUID_RX,
                                         BLECharacteristic::PROPERTY_WRITE
                                       );

  pCharacteristic->setCallbacks(new MyCallbacks());

  // Start the service
  pService->start();

  // Start advertising
  pServer->getAdvertising()->start();
  Serial.println("Waiting a client connection to notify...");
}

void loop() {


  switch (CRstatus) {  //(toInt(CRstatus)) {
    case '0':    // 
      Serial.println("STOP");
      digitalWrite(LED_STOP, HIGH);
      break;
    case '1':    
      Serial.println("VOR");
      digitalWrite(LED_VORWAERTS, HIGH);
      break;
    case '2':    
      Serial.println("LINKS");
      digitalWrite(LED_LINKS, HIGH);
      break;
    case '3':    
      Serial.println("RECHTS");
      digitalWrite(LED_RECHTS, HIGH);
      break;
    case '4':    
      Serial.println("ZURUECK");  // hier gibt es keine LED
      break;
    default:
      Serial.println("Kommando unbekannt");
      
  }



  if (deviceConnected) {
    Serial.printf("*** Sent Value: %d ***\n", txValue);
    pCharacteristic->setValue(&txValue, 1);
    pCharacteristic->notify();
    txValue++;
  }
  delay(1000);

  digitalWrite(LED_VORWAERTS, LOW);
  digitalWrite(LED_STOP, LOW);
  digitalWrite(LED_LINKS, LOW);
  digitalWrite(LED_RECHTS, LOW);
  
}