blzlib is a C library providing an easy interface to acess Bluetooth Low Energy (BLE) Generic Attribute Profile (GATT) Services and Characteristics on Linux. It interfaces with the Bluez Bluetooth daemon on Linux via its D-Bus API. It depends on libsystemd (sd-bus) and is licensed under the LGPLv3.

Currently the following features are supported:

• Discovery / Scanning of nearby BLE devices
• Discovery of services and characteristics
• Read GATT characteristics
• Notify of GATT characteristics (value change notifications)
• Write GATT characteristics
• Efficient write of GATT characteristics by file descriptor (write-without-respose)

• Bluez version 5.49 and higher

• libsystemd: blzlib uses systemds sd-bus library to access the D-Bus API of Bluez.

  sudo apt install libsystemd-dev
  

Currently building with meson as well as cmake is supported.

Meson:

meson build
cd build/
ninja

CMake:

mkdir build
cd build
cmake ..
make

Here is a simple example how to write a characteristic:

blz* blz = blz_init("hci0");
blz_dev* dev = blz_connect(blz, "00:11:22:33:44:55", NULL);
blz_serv* srv = blz_get_serv_from_uuid(dev, "6e400001-b5a3-f393-e0a9-e50e24dcca9e");
blz_char* ch = blz_get_char_from_uuid(srv, "6e400002-b5a3-f393-e0a9-e50e24dcca9e");
blz_char_write(ch, "test", 4);

More real-life examples can be found in the examples/ directory.