B4R Question ArduinoBLE lib wrapping EMPTY issue

[rwblinn]

Hi,

working to wrap the ArduinoBLE library to be used with an Arduino GIGA R1.

Getting this error when compiling a test sketch:

Basic\B4R\Objects\src\rCore.h:614:40: error: expected unqualified-id before ';' token 614 | static B4RString* EMPTY; | ^ In file included from C:...

I confirmed the issue is caused by a macro named EMPTY coming from the Arduino GIGA (mbed / Zephyr / CMSIS) core.
Undefining EMPTY in B4RDefines.h is not sufficient, because the macro is reintroduced per translation unit by the Arduino core.

The only robust fix is to undefine EMPTY locally in rCore.h:

// --- Fix macro collision with Zephyr / mbed ---
#ifdef EMPTY
  #undef EMPTY
#endif
static B4RString* EMPTY;

This keeps API compatibility and avoids renaming core symbols.

Another option would be to rename EMPTY to EMPTYSTR in rCore.h and rCore.cpp:

static B4RString* EMPTYSTR;

static B4RString be_empty;
B4RString* B4RString::EMPTYSTR = be_empty.wrap("");

Is there another solution for this instead modifying the B4R rCore?

 

[Erel]

Another option would be to rename EMPTY to EMPTYSTR in rCore.h and rCore.cpp:

This will not work without updating B4R as the compiler emits code referencing this variable. I will change this variable name in the next update. For now you will need to modify rCore.h.

 

[Peter Simpson]

Hello @rwblinn,
I presume that you're creating another excellent library for the community.

I do have a B4R wrap of the ArduinoBLE library I obviously called it rArduinoBLE, if you would be willing to test it for me. I remember wrapping the Peripheral code, I may or may not have wrapped in the Central code. I wrapped this library when I was updating Erel's original the B4A BLE Peripheral library. I think it's working fully, but I didn't really test it that much as what I needed was for Android production hardware and not Arduino/ESP, so I just left it, well until I saw your post, then I quickly tested this.

ESP32 Peripheral - Android screenshot below:

Let me know, and I'll PM you the code...

 

[rwblinn]

Thanks Peter.
In the meantime have created first version of 2 libraries rArduinoBLECentral & Peripheral.
Tested and working OK.
Happy to test yours.
See my PM.

 

[Peter Simpson]

Hello Everyone,
I'll be releasing my rArduinoBLE for B4R, I wasn't going to do so originally, but after @rwblinn tested it and gave me the go ahead, I will be releasing it after all. this library does both Peripheral and Central devices. I will release 2 examples codes with it, the Peripheral code and the newly renamed Device (now Central) code.

Teaser:
rArduinoBLE

Author: Peter Simpson
Version: 1.00

• BLEDevice
  Represents a remote BLE device discovered during a scan.
  • Functions:
    • Address As String
      Returns the MAC address of the remote device (e.g., "AA:BB:CCD:EE:FF").
    • Connect As Bool
      Attempts to connect to the remote device.
      Returns True if the connection was successful.
    • Connected As Bool
      Checks the connection status. Returns True if currently connected.
    • Disconnect
      Terminates the active connection with the remote device.
    • DiscoverAttributes As Bool
      Queries the remote device for its services and characteristics.
      This must be called and return True before attempting to Read or Write.
    • LocalName As String
      Returns the advertised name of the remote device.
      May return an empty string if the device does not broadcast a name.
    • ReadCharacteristic (ServiceUUID As String, CharUUID As String) As Byte()
      Reads data from a remote characteristic.
      ServiceUUID: The Service UUID.
      CharUUID: The Characteristic UUID.
      Returns an ArrayByte containing the data, or Null if the read failed.
    • RSSI As Int
      Returns the Received Signal Strength Indicator.
      Typically ranges from -100 (weak) to -30 (strong).
    • WriteCharacteristic (ServiceUUID As String, CharUUID As String, Data As Byte())
      Writes data to a characteristic on the remote device.
      ServiceUUID: The 128-bit or 16-bit Service UUID.
      CharUUID: The Characteristic UUID to target.
      Data: The ArrayByte containing the payload.
• BLEMaster
  The main controller for Bluetooth Low Energy.
  Supports both Peripheral mode (broadcasting services) and Central mode (scanning for remote devices).
  • Fields:
    • Appearance As Int
      Sets the 16-bit appearance value for the device.
      --- SOME OF THESE CODES BELOW, MAY NOT BE RECOGNISED ON YOUR DEVICE. ---.
      Unknown (0x0000), Phone (0x0040), Computer (0x0080), Watch (Generic) (0x00C0), Watch: Sports Watch (0x00C1),
      Clock (0x0100), Display (0x0140), Remote Control (0x0180), Eye-glasses (0x01C0), Tag (0x0200), Keyring (0x0240),
      Media Player (0x0280), Barcode Scanner (0x02C0), Thermometer (Generic) (0x0300), Thermometer: Ear (0x0301),
      Heart Rate Sensor (Generic) (0x0340), Heart Rate Sensor: Belt (0x0341), Blood Pressure (Generic) (0x0380),
      Blood Pressure: Arm (0x0381), Blood Pressure: Wrist (0x0382), Human Interface Device (HID) (0x03C0),
      HID: Keyboard (0x03C1), HID: Mouse (0x03C2), HID: Joystick (0x03C3), HID: Gamepad (0x03C4),
      HID: Digitizer Tablet (0x03C5), HID: Card Reader (0x03C6), HID: Digital Pen (0x03C7), HID: Barcode Scanner (0x03C8).
    • DeviceName As String
      Sets or gets the device name (GATT service name) seen after connection.
    • LocalName As String
      Sets or gets the local name that the device will broadcast.
  • Functions:
    • AddService (Service As B4R::B4RLocalService*)
      Adds a local service to the peripheral.
      Service: The LocalService object which must contain at least one characteristic.
    • Advertise
      Starts broadcasting BLE advertisement packets.
      This makes the device visible to other BLE centrals (like smartphones).
    • Available As B4R::B4RBLEDevice*
      Checks for discovered devices during an active scan.
      Returns a BLEDevice object if a device was found, or Null if no new devices are available.
    • Begin As Bool
      Initialises the BLE radio hardware.
      Returns True if the radio was successfully started.
      Ensure your board supports BLE (e.g., ESP32, Arduino Nano 33 BLE).
    • Poll
      Handles underlying BLE stack events.
      In Peripheral mode, this should be called frequently within a loop to maintain connections.
    • Scan
      Starts scanning for nearby BLE peripheral devices.
      Use the Available method to retrieve discovered devices.
    • SetAdvertisedService (Service As B4R::B4RLocalService*)
      Sets the primary service UUID to be broadcast in the advertisement packet.
      Service: The service that scanning central devices will see before connecting.
    • SetAppearance (Value As Int)
      Alternative method to set the appearance value via a function call.
    • StopScan
      Stops the current scanning operation to save power or prepare for connection.
• LocalCharacteristic
  Represents a data point hosted on your device that centrals can interact with.
  • Functions:
    • GetValue As Byte()
      Returns the most recent value written to this characteristic by a connected central device.
    • Initialize (UUID As String, Properties As Byte, Size As Int)
      
      Initialises the characteristic.
      UUID: The unique identifier for this data point.
      Properties: Supported bits.
      1 = Read
      2 = Write
      4 = Write Without Response
      8 = Notify
      16 = Indicate
      Combined Properties: Common examples.
      3 = Read + Write (1 + 2)
      6 = Write + Write Without Response (2 + 4)
      7 = Read + Write + Write Without Response (1 + 2 + 4)
      15 = Read + Write + Write Without Response + Notify (1 + 2 + 4 + 8)
      Size: The maximum data size in bytes for the value buffer.
    • SetValue (Data As Byte())
      Updates the value stored in this characteristic.
      Centrals will see this updated value on their next read or notification.
    • Written As Bool
      Checks if a remote central device has written a new value to this characteristic since this method was last checked.
• LocalService
  Represents a BLE service hosted by your ESP32/Arduino.
  • Functions:
    • AddCharacteristic (Characteristic As B4R::B4RLocalCharacteristic*)
      Adds a characteristic to this service.
      Call this before adding the service to the BLEMaster.
    • Initialize (UUID As String)
      Initialises the service.
      UUID: The unique identifier for this service (e.g., "180F" for Battery Service).

BLE Library Compatibility Table​

Board / Family	BLE hardware	ArduinoBLE compatible	Works with this library	Notes
Arduino Nano 33 BLE	✔	✔	✔	Fully supported (nRF52840)
Arduino Nano 33 BLE Sense	✔	✔	✔	Fully supported
Arduino Nano 33 BLE Sense Rev2	✔	✔	✔	Fully supported
Arduino Edge Control	✔	✔	✔	Uses same BLE stack
Arduino Portenta H7 (mbed)	✔	✔	✔	Works in mbed mode
Arduino Nicla Sense ME	✔	✔	✔	Fully supported
Arduino Nicla Vision	✔	✔	✔	Fully supported
Arduino Nicla Voice	✔	✔	✔	Fully supported
ESP32 DevKit V1 (DOIT)	✔	✔	✔	Yes - Already tested by me
ESP32-WROOM-32	✔	✔	✔	Yes - Already tested by me
ESP32-WROVER	✔	✔	✔	Yes - Already tested by me
ESP32-S3	✔	✔	✔	BLE 5.0 capable
ESP32-C3	✔	✔	✔	BLE 5.0 capable
ESP32-C6	✔	✔	✔	BLE 5.0 capable
Nano RP2040 Connect	✔	⚠ Partial	⚠ Works but slower	BLE via NINA module
Portenta X8	✔	⚠ Partial	⚠ Works in Arduino mode	Not recommended for timing‑critical BLE
ESP32-S2				No BLE hardware - Add HM‑10
ESP8266				No BLE hardware - Add HM‑10
Arduino Uno / Mega / Leonardo				No BLE hardware - Add HM‑10
Arduino Due				No BLE hardware - Add HM‑10
Teensy 3.x / 4.x	✔			Uses different BLE stack
Adafruit nRF52 boards	✔			Use Bluefruit, not ArduinoBLE
STM32 boards	✔			Use STM32BLE, not ArduinoBLE

Enjoy...