Multiple Servers - Githubissues

luizahiginoss commented 6 years ago

I'm trying to develop a bluetooth network with one client and several servers, but they communicate with the client based on "notify". If they have the same service UUID and characteristic UUID i won't be able to do that? Probably i'm just getting confused with GATT and GAP aplications for BLE... Can u help me?

I haven't started the tests yet, but I'm using the BLE examples...

outlandnish commented 6 years ago

@luizahiginoss https://github.com/nkolban/esp32-snippets/pull/541 should help. I made this mod and use it with PlatformIO / ESP32 quite successfully with multiple servers that have the same service and characteristic UUIDs.

luizahiginoss commented 6 years ago

I tried to use one ESP32 as the client and other 3 ESPs as servers. The client only connect with one server and receive the value from its characteristic. The other 2 continue to advertise, but their characteristics values are never showed and the connection never completed.

luizahiginoss commented 6 years ago

The client code I'm using is the one below

/**
 * A BLE client example that is rich in capabilities.
 */

#include "BLEDevice.h"
//#include "BLEScan.h"

// The remote service we wish to connect to.
static BLEUUID serviceUUID("91bad492-b950-4226-aa2b-4ede9fa42f59");
// The characteristic of the remote service we are interested in.
static BLEUUID    charUUID("0d563a58-196a-48ce-ace2-dfec78acc814");

static BLEAddress *pServerAddress;
static boolean doConnect = false;
static boolean connected = false;
static BLERemoteCharacteristic* pRemoteCharacteristic;
const uint8_t v[]={0x1,0x0};

static void notifyCallback(
  BLERemoteCharacteristic* pBLERemoteCharacteristic,
  uint8_t* pData,
  size_t length,
  bool isNotify) {
    Serial.print("Notify callback for characteristic ");
    Serial.print(pBLERemoteCharacteristic->getUUID().toString().c_str());
    Serial.print(" of data length ");
    Serial.println(length);
}

bool connectToServer(BLEAddress pAddress) {
    Serial.print("Forming a connection to ");
    Serial.println(pAddress.toString().c_str());

    BLEClient*  pClient  = BLEDevice::createClient();
    Serial.println(" - Created client");

    // Connect to the remove BLE Server.
    pClient->connect(pAddress);
    Serial.println(" - Connected to server");

    // Obtain a reference to the service we are after in the remote BLE server.
    BLERemoteService* pRemoteService = pClient->getService(serviceUUID);
    if (pRemoteService == nullptr) {
      Serial.print("Failed to find our service UUID: ");
      Serial.println(serviceUUID.toString().c_str());
      return false;
    }
    Serial.println(" - Found our service");

    // Obtain a reference to the characteristic in the service of the remote BLE server.
    pRemoteCharacteristic = pRemoteService->getCharacteristic(charUUID);
    if (pRemoteCharacteristic == nullptr) {
      Serial.print("Failed to find our characteristic UUID: ");
      Serial.println(charUUID.toString().c_str());
      return false;
    }
    Serial.println(" - Found our characteristic");

    // Read the value of the characteristic.
    std::string value = pRemoteCharacteristic->readValue();
    Serial.print("The characteristic value was: ");
    Serial.println(value.c_str());

    pRemoteCharacteristic->registerForNotify(notifyCallback);
    pRemoteCharacteristic->getDescriptor(BLEUUID((uint16_t)0x2902))->writeValue((uint8_t*)v,2,true);
}   
/**
 * Scan for BLE servers and find the first one that advertises the service we are looking for.
 */
class MyAdvertisedDeviceCallbacks: public BLEAdvertisedDeviceCallbacks {
 /**
   * Called for each advertising BLE server.
   */
  void onResult(BLEAdvertisedDevice advertisedDevice) {
    Serial.print("BLE Advertised Device found: ");
    Serial.println(advertisedDevice.toString().c_str());

    // We have found a device, let us now see if it contains the service we are looking for.
    if (advertisedDevice.haveServiceUUID() && advertisedDevice.getServiceUUID().equals(serviceUUID)) {

      // 
      Serial.print("Found our device!  address: "); 
      advertisedDevice.getScan()->stop();

      pServerAddress = new BLEAddress(advertisedDevice.getAddress());
      doConnect = true;

    } // Found our server
  } // onResult
}; // MyAdvertisedDeviceCallbacks

void setup() {
  Serial.begin(115200);
  Serial.println("Starting Arduino BLE Client application...");
  BLEDevice::init("");

  // Retrieve a Scanner and set the callback we want to use to be informed when we
  // have detected a new device.  Specify that we want active scanning and start the
  // scan to run for 30 seconds.
  BLEScan* pBLEScan = BLEDevice::getScan();
  pBLEScan->setAdvertisedDeviceCallbacks(new MyAdvertisedDeviceCallbacks());
  pBLEScan->setActiveScan(true);
  pBLEScan->start(30);
} // End of setup.

// This is the Arduino main loop function.
void loop() {

  // If the flag "doConnect" is true then we have scanned for and found the desired
  // BLE Server with which we wish to connect.  Now we connect to it.  Once we are 
  // connected we set the connected flag to be true.
  if (doConnect == true) {
    if (connectToServer(*pServerAddress)) {
      Serial.println("We are now connected to the BLE Server.");
      connected = true;
    } else {
      Serial.println("We have failed to connect to the server; there is nothin more we will do.");
    }
    doConnect = false;
  }

  // If we are connected to a peer BLE Server, update the characteristic each time we are reached
  // with the current time since boot.
  if (connected) {
    //String newValue = "Time since boot: " + String(millis()/1000);
    //Serial.println("Setting new characteristic value to \"" + newValue + "\"");
    std::string value = pRemoteCharacteristic->readValue();
    Serial.print("The characteristic value was: ");
    Serial.println(value.c_str());

    //pRemoteCharacteristic->registerForNotify(notifyCallback);
    // Set the characteristic's value to be the array of bytes that is actually a string.
    //pRemoteCharacteristic->writeValue(newValue.c_str(), newValue.length());
  }

  delay(1000); // Delay a second between loops.
} // End of loop

And the Notify code I'm using is the one below

/*
    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: 4fafc201-1fb5-459e-8fcc-c5c9c331914b
   And has a characteristic of: beb5483e-36e1-4688-b7f5-ea07361b26a8
   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.
   A connect hander associated with the server starts a background task that performs notification
   every couple of seconds.
*/
#include <BLEDevice.h>
#include <BLEServer.h>
#include <BLEUtils.h>
#include <BLE2902.h>

BLEServer* pServer = NULL;
BLECharacteristic* pCharacteristic = NULL;
bool deviceConnected = false;
bool oldDeviceConnected = false;
uint8_t value = 0;

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

#define SERVICE_UUID        "91bad492-b950-4226-aa2b-4ede9fa42f59"
#define CHARACTERISTIC_UUID "0d563a58-196a-48ce-ace2-dfec78acc814"

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("ESP30");

  // 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
  pCharacteristic = pService->createCharacteristic(
                      CHARACTERISTIC_UUID,
                      BLECharacteristic::PROPERTY_READ   |
                      BLECharacteristic::PROPERTY_WRITE  |
                      BLECharacteristic::PROPERTY_NOTIFY |
                      BLECharacteristic::PROPERTY_INDICATE
                    );

  // https://www.bluetooth.com/specifications/gatt/viewer?attributeXmlFile=org.bluetooth.descriptor.gatt.client_characteristic_configuration.xml
  // Create a BLE Descriptor
  pCharacteristic->addDescriptor(new BLE2902());

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

  BLEAdvertising *pAdvertising = pServer->getAdvertising();
  pAdvertising->addServiceUUID(SERVICE_UUID);    //<--- ADD THIS LINE
  pAdvertising->start();
  // Start advertising
  pServer->getAdvertising()->start();
  Serial.println("Waiting a client connection to notify...");
}

void loop() {
    // notify changed value
    if (deviceConnected) {
        pCharacteristic->setValue("Hello world says Luli");
        pCharacteristic->notify();
        value++;
        delay(20000); // bluetooth stack will go into congestion, if too many packets are sent
    }
    // 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;
    }
}

outlandnish commented 6 years ago

It looks like the code above doesn't try connecting because doConnect gets set to false after the first connection. I can post an example of it connecting to multiple servers later today.

luizahiginoss commented 6 years ago

Ok! Ty

luizahiginoss commented 6 years ago

I was able to connect two devices (now using server code) making a few changes in the Client code. It works for at least 1 ou 2 minutes.

Forming a connection to 30:ae:a4:92:0b:be
 - Created client
 - Connected to server
 - Found our service
 - Found our characteristic
The characteristic value was: Hello World says Xastre
We are now connected to the BLE Server. 1
E (167657) BT: bta_gattc_conn_cback() - cif=3 connected=0 conn_id=3 reason=0x0016
E (167659) BT: bta_gattc_conn_cback() - cif=4 connected=0 conn_id=4 reason=0x0016
Forming a connection to 30:ae:a4:92:6b:72
 - Created client
 - Connected to server
 - Found our service
 - Found our characteristic
The characteristic value was: Hello World says Luli
We are now connected to the BLE Server 2.
E (171227) BT: bta_gattc_conn_cback() - cif=3 connected=0 conn_id=3 reason=0x0016
E (171230) BT: bta_gattc_conn_cback() - cif=4 connected=0 conn_id=4 reason=0x0016
Forming a connection to 30:ae:a4:92:0b:be
 - Created client
 - Connected to server
 - Found our service
 - Found our characteristic
The characteristic value was: Hello World says Xastre
We are now connected to the BLE Server. 1
E (174902) BT: bta_gattc_conn_cback() - cif=3 connected=0 conn_id=3 reason=0x0016
E (174905) BT: bta_gattc_conn_cback() - cif=4 connected=0 conn_id=4 reason=0x0016

--> So far, the messages are completely normal because I am using pClient->disconnect();, and then this happens

Forming a connection to 30:ae:a4:92:6b:72
 - Created client
E (178064) BT: bta_gattc_conn_cback() - cif=3 connected=0 conn_id=3 reason=0x003e
E (178065) BT: p_conn is NULL in bta_gattc_conn_cback

E (178066) BT: bta_gattc_conn_cback() - cif=4 connected=0 conn_id=4 reason=0x003e
E (178073) BT: p_conn is NULL in bta_gattc_conn_cback

We are now connected to the BLE Server 2.

We are now connected to the BLE Server 2.
Forming a connection to 30:ae:a4:92:0b:be
 - Created client
 - Connected to server
 - Found our service
 - Found our characteristic
The characteristic value was: Hello World says Xastre
We are now connected to the BLE Server. 1
E (181757) BT: bta_gattc_conn_cback() - cif=3 connected=0 conn_id=3 reason=0x0016
E (181760) BT: bta_gattc_conn_cback() - cif=4 connected=0 conn_id=4 reason=0x0016
E (181767) BT: bta_gattc_conn_cback() - cif=5 connected=0 conn_id=5 reason=0x0016
Forming a connection to 30:ae:a4:92:6b:72
 - Created client
E (184756) BT: application already registered.
E (184756) BT: Register with GATT stack failed.

E (184758) BT: application already registered.
E (184762) BT: Register with GATT stack failed.

E (184766) BT: bta_gattc_process_api_open Failed, unknown client_if: 0

After this, everything stops.

The code I'm using for client is in this txt file

BLE_client.txt

Donderda commented 6 years ago

Were you able to fix this problem?

luizahiginoss commented 6 years ago

No, I wasn't...

mangooose commented 6 years ago

Can you please provide multiple servers connection example? I was able to connect to 2 servers and get the characteristics but somehow writeValue works only for the first server and hangs there.