BLE Reboot on Disconnect, after reading characteristic

azziNine
Posts: 1
Joined: Fri Nov 22, 2019 5:51 am

BLE Reboot on Disconnect, after reading characteristic

Postby azziNine » Fri Nov 22, 2019 6:11 am

Hello, I'm using some modified example code to connect an ESP32 BLE client to an ESP32 BLE Server. I need to be able to connect to multiple servers, so it is imperative that I can disconnect successfully from each server.

I'm able to connect to server & find the characteristic.

If I don't read the characteristic, I'm able to connect & then disconnect without any issue.

If I read the characteristic value & then try to disconnect, I get the following error:

Code: Select all

00:02:33.902 -> CORRUPT HEAP: Bad head at 0x3ffdec90. Expected 0xabba1234 got 0x3ffdef3c
00:02:33.902 -> assertion "head != NULL" failed: file "/home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/heap/multi_heap_poisoning.c", line 214, function: multi_heap_free
00:02:33.937 -> abort() was called at PC 0x400e6de3 on core 0
00:02:33.937 -> 
00:02:33.937 -> Backtrace: 0x40091448:0x3ffd15d0 0x40091679:0x3ffd15f0 0x400e6de3:0x3ffd1610 0x400910d5:0x3ffd1640 0x40084b26:0x3ffd1660 0x400850e1:0x3ffd1680 0x4000bec7:0x3ffd16a0 0x400fd0d9:0x3ffd16c0 0x400fcc1a:0x3ffd16e0 0x400fccdc:0x3ffd1700 0x40136943:0x3ffd1720 0x40138242:0x3ffd1740 0x40135fe6:0x3ffd19d0 0x40136125:0x3ffd19f0 0x4013e662:0x3ffd1a10 0x401136ca:0x3ffd1a30 0x4008e089:0x3ffd1a60
00:02:33.971 -> 
00:02:33.971 -> Rebooting...
00:02:33.971 -> ets Jun  8 2016 00:22:57
Any thoughts on what I'm doing wrong here?

I've got 2 lines below indicated with comments starting with "// ***" that show where my problem specifically lies.

Full code below:

Code: Select all

#include "BLEDevice.h"

// The remote service we wish to connect to.
#define SERVICE_UUID        "59f30011-a621-11e1-802a-5aa538984bd1"
static BLEUUID serviceUUID(SERVICE_UUID);

// The characteristic of the remote service we are interested in.
#define CHARACTERISTIC_UUID "98e38b21-a622-11e1-802a-5aa538984bd1"
static BLEUUID    charUUID(CHARACTERISTIC_UUID);

static boolean doConnect = false;
static boolean connected = false;
static boolean doScan = false;
static BLERemoteCharacteristic* pRemoteCharacteristic;
static BLEAdvertisedDevice* myDevice;

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);
    Serial.print("data: ");
    Serial.println((char*)pData);
}

class MyClientCallback : public BLEClientCallbacks {
  void onConnect(BLEClient* pclient) {
  }

  void onDisconnect(BLEClient* pclient) {
    connected = false;
    Serial.println("onDisconnect");
  }
};

bool connectToServer() {
    Serial.print("Forming a connection to ");
    Serial.println(myDevice->getAddress().toString().c_str());
    
    BLEClient*  pClient  = BLEDevice::createClient();
    Serial.println(" - Created client");

    MyClientCallback* tmpMyClientCallback = new MyClientCallback();
    
    pClient->setClientCallbacks(tmpMyClientCallback);

    // Connect to the remote BLE Server.
    pClient->connect(myDevice);  // if you pass BLEAdvertisedDevice instead of address, it will be recognized type of peer device address (public or private)
    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());
      pClient->disconnect();
      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());
      pClient->disconnect();
      return false;
    }
    Serial.println(" - Found our characteristic");

    // Read the value of the characteristic.
    if(pRemoteCharacteristic->canRead()) {
      std::string value = pRemoteCharacteristic->readValue(); // *** if I comment this out, disconnects correctly.
//      Serial.print("The characteristic value was: ");
//      Serial.println(value.c_str());
    }

    pClient->disconnect(); // *** if I comment this out, does not fail, but eventually runs out of memory/stops looping

    connected = false; //true;
    return false; //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.isAdvertisingService(serviceUUID)) {

      BLEDevice::getScan()->stop();
      myDevice = new BLEAdvertisedDevice(advertisedDevice);
      doConnect = true;
      doScan = true;

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


void setup() {
  Serial.begin(115200);
  Serial.println("Starting Client");
  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 5 seconds.
  BLEScan* pBLEScan = BLEDevice::getScan();
  pBLEScan->setAdvertisedDeviceCallbacks(new MyAdvertisedDeviceCallbacks());
  pBLEScan->setInterval(1349);
  pBLEScan->setWindow(449);
  pBLEScan->setActiveScan(true);
  pBLEScan->start(5, false);
} // End of setup.

void loop() {
  Serial.println("Begin loop...");

  if (doConnect == true) {
    if (connectToServer()) {
      Serial.println("We are now connected to the BLE Server.");
    } else {
      Serial.println("We have failed to connect to the server; there is nothin more we will do.");
    }
    doConnect = false;
  }

  if (connected) {
    std::string oldValue = pRemoteCharacteristic->readValue();
    Serial.print("Old characteristic value \"");
    Serial.print(oldValue.c_str());
    Serial.println("\"");
    String newValue = "Time since boot: " + String(millis()/1000);
    Serial.println("Setting new characteristic value to \"" + newValue + "\"");
  }else if(doScan){
    BLEDevice::getScan()->start(0);  // this is just eample to start scan after disconnect, most likely there is better way to do it in arduino
  }
  
  delay(1000); // Delay a second between loops.
  Serial.println("End loop...");
} // End of loop

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