Data is transmitted from M5Stack to iOS application by BLE to drive switch

2018/10/04
23:58

Data is transmitted from M5Stack to iOS application by BLE to drive switch

Hello everyone! I’m RoboTakao.

Last time I tried to send data from iOS application to M5Stack with BLE and light the LED .

This time I will send data from M5Stack to iOS application with BLE and try driving the switch on iOS application.

Only the sketch on the M5Stack side was changed for the last code.

Description of the sketch

Send a String with setValue.
"*" Is added to "Pressed", and the end of the data is judged on the iOS application side.

pTxCharacteristic->setValue((std::string)"Pressed*");
pTxCharacteristic->notify();

Press the A and B buttons to move the iOS slide switch.

Sample sketch


/*
    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 
#include 
#include 
#include 
#include 

BLEServer *pServer = NULL;
BLECharacteristic * pTxCharacteristic;
bool deviceConnected = false;
bool oldDeviceConnected = false;
uint8_t txValue = 0;

int LEDPinNo = 22;

// 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();

      M5.Lcd.println("Receive");
      Serial.println("Receive");
      

      int from = 0;

      boolean noMoreEvent = false;

      while (!noMoreEvent) {
        int index = rxValue.find("*", from);

        if (index < 0) {
          noMoreEvent = true;
        }
        else {
          std::string command = rxValue.substr(from, index);

          if (command == "On") {
            digitalWrite(LEDPinNo, HIGH);
            M5.Lcd.println("LED On");
            Serial.println("LED On");
          } else if (command == "Off") {
            digitalWrite(LEDPinNo, LOW);
            M5.Lcd.println("LED Off");
            Serial.println("LED Off");
          }

          from = index + 1;
        }
      }
    }
};


void setup() {
  M5.begin();
  
  Serial.begin(115200);

  pinMode(LEDPinNo, OUTPUT); //22pin OUTPUT mode

  // Create the BLE Device
  BLEDevice::init("UART Service");

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

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

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

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

  pRxCharacteristic->setCallbacks(new MyCallbacks());

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

  // Start advertising
  pServer->getAdvertising()->start();
  M5.Lcd.println("Waiting a client connection to notify...");
  Serial.println("Waiting a client connection to notify...");
}

void loop() {

    // Button A B
    if (deviceConnected) {
        if(M5.BtnA.wasPressed()) {
            M5.Lcd.printf("wasPressed A \r\n");
            Serial.println("wasPressed A \r\n");
            pTxCharacteristic->setValue((std::string)"Pressed*");
            pTxCharacteristic->notify();
        }

       if(M5.BtnB.wasPressed())
       {
            M5.Lcd.printf("wasPressed B \r\n");
            Serial.println("wasPressed B \r\n");
            pTxCharacteristic->setValue((std::string)"Released*");
            pTxCharacteristic->notify();
       }
    }

    // disconnecting
    if (!deviceConnected && oldDeviceConnected) {
        delay(500); // give the bluetooth stack the chance to get things ready
        pServer->startAdvertising(); // restart advertising
        M5.Lcd.println("start advertising");
        Serial.println("start advertising");
        oldDeviceConnected = deviceConnected;
    }
    // connecting
    if (deviceConnected && !oldDeviceConnected) {
		// do stuff here on connecting
        oldDeviceConnected = deviceConnected;
    }

    M5.update();
}