Receiving specific BLE data

MIT App Inventor Help
1

Hi team i need help. I want to check and identify each data receive using bluetooth BLE with this block i can't receive the data

blocks (9)
blocks (9)1404×690 98.3 KB

2

Post your exported aia file and the sketch of the device transmitting the data.

3 
#include <BLEDevice.h>
#include <BLEServer.h>
#include <BLEUtils.h>
#include <BLE2902.h>

// create pointers
BLEServer* pServer = NULL;
BLECharacteristic* pCharacteristic = NULL;
BLECharacteristic* pCharacteristic_1 = NULL;
BLECharacteristic* pCharacteristic_2 = NULL;

BLEDescriptor *pDescr;
BLE2902 *pBLE2902;

bool deviceConnected = false;
bool oldDeviceConnected = false;

uint32_t value = 0;
String Current_cordinate = "140321000";
uint32_t Reci_cellSite_Dist = 8500;

static BLEUUID BLESERVICE_UUID("4fafc201-1fb5-459e-8fcc-c5c9c331914b");   // this allow the use of more than four services
#define SERVICE_UUID        "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHAR_UUID          "beb5483e-36e1-4688-b7f5-ea07361b26a8"
#define CHAR1_UUID          "e3223119-9445-4e96-a4a1-85358c4046a2"
#define CHAR2_UUID          "8a73ddbb-3fdd-4c04-9f0e-606546d8d36d" 

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


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

  // Create the BLE Device
  BLEDevice::init("ESP32");

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

  //BLEService *pService = pServer->createService(SERVICE_UUID);
   BLEService *pService = pServer->createService(BLESERVICE_UUID, 20, 0);       // this is the continuetion of the code that 
                                                                                // allow's the use of more than four services
  // Create a BLE Characteristic
  pCharacteristic = pService->createCharacteristic(
                        CHAR_UUID,
                        BLECharacteristic::PROPERTY_NOTIFY
);                   

  pCharacteristic_1 = pService->createCharacteristic(
                      CHAR1_UUID,
                      //BLECharacteristic::PROPERTY_NOTIFY |
                      BLECharacteristic::PROPERTY_INDICATE |
                      BLECharacteristic::PROPERTY_READ   |
                      BLECharacteristic::PROPERTY_WRITE  
                    ); 
// Create a BLE Descriptor
  
  pDescr = new BLEDescriptor((uint16_t)0x2901);
  pDescr->setValue("A very interesting variable");
  pCharacteristic->addDescriptor(pDescr);
  
  pBLE2902 = new BLE2902();
  pBLE2902->setNotifications(true);
  
  // Add all Descriptors here
  pCharacteristic->addDescriptor(pBLE2902);
  pCharacteristic_1->addDescriptor(new BLE2902());
  // After defining the desriptors, set the callback functions
  pCharacteristic_1->setCallbacks(new CharacteristicCallBack());

  pCharacteristic_2->addDescriptor(new BLE2902());
  pCharacteristic_2->setCallbacks(new CharacteristicCallBack()); 

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

  // Start advertising
  BLEAdvertising *pAdvertising = BLEDevice::getAdvertising();
  pAdvertising->addServiceUUID(SERVICE_UUID);
  pAdvertising->setScanResponse(false);
  pAdvertising->setMinPreferred(0x0);  // set value to 0x00 to not advertise this parameter
  BLEDevice::startAdvertising(); 
  pServer->getAdvertising()->start();  
  Serial.println("Waiting a client connection to notify...");



void loop() {
  if(Serial.available() > 0){
    Current_cordinate = Serial.read();
    Current_cordinate.c_str();
  }
    // notify changed value
    if (deviceConnected) {
        pCharacteristic->setValue(value);
        pCharacteristic->notify();
        value++;
       // delay(1000);
       
   Serial.println("Sending current_cordinate.......");
       pCharacteristic_1->setValue( Current_cordinate .c_str());
       pCharacteristic_1->indicate();
       Serial.println("Sent" + Current_cordinate);
       //Current_cordinate++;
       pCharacteristic_2->setValue(Reci_cellSite_Dist);
       pCharacteristic_2->indicate();
       delay(1000);
    }
    // disconnecting
    if (!deviceConnected && oldDeviceConnected) {
        delay(500); // give the bluetooth stack the chance to get things ready
        pServer->startAdvertising(); // restart advertising
        Serial.println("start advertising");
        oldDeviceConnected = deviceConnected;
    }
    // connecting
    if (deviceConnected && !oldDeviceConnected) {
        // do stuff here on connecting
        oldDeviceConnected = deviceConnected;
    }
}

BLE_controller (2).aia (693.5 KB)

4

Bytevalues is a list of hopefully four numbers in the range 0 to 255.

If I read the sketch right it should be a uint32.

Applying text operators to a list forces JSON conversion, which you don't want, if you hope to access individual list items 1-4.

Use blue list select blocks on bytevalues to make get its items

Verify you got all 4 items first, by checking length of list bytevalues.

If no bytes arrive, that might be because of those delay() calls in the sketch. Those prevent other code sections in the void loop from getting a chance to run.

Better to replace those with time checks against deadlines, so you don't block execution.

5

I forgot to mention that there is a ble Register for Bytes block that would make it unnecessary to keep asking for reads from the sketch.

The data would arrive in the bytes received event on its own.

6

I can find list select block can you please give me an example of BLE list select block

7