BLE serial gibberish

PlatformIO IDE
1

This BLE Client script compiles and uploads with no issue, but the serial output is garbage:

This is Termite:
õKŸ:[14]8å¯"omn^.pÒQÁá5[11]òe[1D]Ñÿ˜[19]Hì[14])Do:fOÍ€qå[11]ý!þ)-)”¼½
¦!¦[0C]¶Jü˜[19]HÖ[10]9B®¥H"­Åý[10]9BR´ÔJµ[0E])[10]9B®¥¤![08]!ç[10]9B¢ÌPG„!å[10]9B®)†!¥¥[06]þÞ[1C][10]µ)

This is the VSCode output:
�␙H�␔)Do��3�␓��!"S����R����!�b5�RS�`��␐9␂R��)���cr夌c���!␌) ␋B�~�␐9"��e␞B␔B

There are characters in this mess. I see numbers. I’m expecting numbers.

2

Check the baud rate in the code, then make sure that monitor_speed = baudrate in the platformio.ini file.

Failing that, try a baudrate that isn’t 115200 as that one is well out of error percentage range. (For an ATmega328 that is.)

Cheers,
Norm.

1 Like
3

Baud rate isn’t in the .ini, and everything is set to 9600.

I think I’m seeing reported data AND gibberish.

Output is supposed to be text and UUIDs.

4

I might try to display something on OLED.
“serviceUUID”

5

"control reaches end of non-void function at line 98, which is a }

6 
/**
 * A BLE client example that is rich in capabilities.
 * There is a lot new capabilities implemented.
 * author unknown
 * updated by chegewara
 */
#include <Arduino.h>
#include "BLEDevice.h"
//#include "BLEScan.h"

// The remote service we wish to connect to.
static BLEUUID serviceUUID("4fafc201-1fb5-459e-8fcc-c5c9c331914b");
// The characteristic of the remote service we are interested in.
static BLEUUID charUUID("beb5483e-36e1-4688-b7f5-ea07361b26a8");

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.begin(9600);
  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");

  pClient->setClientCallbacks(new MyClientCallback());

  // Connect to the remove 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();
    Serial.print("The characteristic value was: ");
    Serial.println(value.c_str());
  }

  if (pRemoteCharacteristic->canNotify())
    pRemoteCharacteristic->registerForNotify(notifyCallback);

  connected = 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 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 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.

// 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())
    {
      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 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 + "\"");

    // Set the characteristic's value to be the array of bytes that is actually a string.
    pRemoteCharacteristic->writeValue(newValue.c_str(), newValue.length());
  }
  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.
} // End of loop
7

None of the characters that make it through appear to have any meaning.

8

is the end of a function which is declared as

returning bool. The function doesn’t in this code path though. Thus it’s technically undefined behavior and can crash the program. The compiler is correct with

A

return true;

should be placed at the end of the function to indicate success.

1 Like
9

No it isn’t! In this function:

It is indeed 9600. However, in this one, it is 115200:

Add monitor_speed = 115200 to the platformio.ini file, just to be sure that the code and monitor definitely match up.

This function returns false in a couple of places. However, if it reaches the end, it does not return a value. I assume it should return true?

Cheers,
Norm.

1 Like