wrtcoder / bluetoe

C++ Bluetooth LE Server (GATT)

Bluetoe

Overview

Bluetoe implements a GATT server with a very low memory footprint and a convenience C++ interface. Bluetoe makes easy things easy but gives the opportunity to fiddle with all the low level GATT details if necessary. The main target of Bluetoe is to be implemented on very small microcontrollers. Here is a complete example of a small GATT server, that allows a client to controll an IO pin, running on a nrf51422:

#include <bluetoe/server.hpp>
#include <bluetoe/bindings/nrf51.hpp>
#include <nrf.h>

using namespace bluetoe;

static constexpr int io_pin = 19;

static std::uint8_t io_pin_write_handler( bool state )
{
    // the GPIO pin according to the received value: 0 = off, 1 = on
    NRF_GPIO->OUT = state
        ? NRF_GPIO->OUT | ( 1 << io_pin )
        : NRF_GPIO->OUT & ~( 1 << io_pin );

    return error_codes::success;
}

typedef server<
    service<
        service_uuid< 0xC11169E1, 0x6252, 0x4450, 0x931C, 0x1B43A318783B >,
        characteristic<
            free_write_handler< bool, io_pin_write_handler >
        >
    >
> blinky_server;

blinky_server gatt;

nrf51< blinky_server > gatt_srv;

int main()
{
    // Init GPIO pin
    NRF_GPIO->PIN_CNF[ io_pin ] =
        ( GPIO_PIN_CNF_DRIVE_S0H1 << GPIO_PIN_CNF_DRIVE_Pos ) |
        ( GPIO_PIN_CNF_DIR_Output << GPIO_PIN_CNF_DIR_Pos );

    for ( ;; )
        gatt_srv.run( gatt );
}

Documentation

http://torstenrobitzki.github.io/bluetoe/

L2CAP

Bluetoe ships with its own link layer. Currently a link layer based on the nrf51422 is under construction and is already usable. The link layer implementation will be based and tested on an abstract device, called a scheduled radio and should be easily ported to similar hardware. As Bluetoe is a GATT server implementation, only that parts of the link layer are implemented, that are nessary. Bluetoe can easily adapted to any other existing L2CAP implementation (based on HCI for example).

Current State

The following table show the list of GATT procedures and there implementation status and there planned implementation status:

Feature	Sub-Procedure	Status
Server Configuration	Exchange MTU	implemented
Primary Service Discovery	Discover All Primary Services	implemented
	Discover Primary Service By Service UUID	implemented
Relationship Discovery	Find Included Services	implemented
	Declare Secondary Services	implemented
Characteristic Discovery	Discover All Characteristic of a Service	implemented
	Discover Characteristic by UUID	implemented
Characteristic Descriptor Discovery	Discover All Characteristic Descriptors	implemented
Characteristic Value Read	Read Characteristic Value	implemented
	Read Using Characteristic UUID	implemented
	Read Long Characteristic Value	implemented
	Read Multiple Characteristic Values	implemented
Characteristic Value Write	Write Without Response	implemented
	Signed Write Without Response	not planned
	Write Characteristic Value	implemented
	Write Long Characteristic Values	implemented
	Characteristic Value Reliable Writes	implemented
Characteristic Value Notification	Notifications	implemented
Characteristic Value Indication	Indications	implemented
Characteristic Descriptor Value Read	Read Characteristic Descriptors	implemented
	Read Long Characteristic Descriptors	implemented
Characteristic Descriptor Value Write	Write Characteristic Descriptors	implemented
	Write Long Characteristic Descriptors	implemented
Cryptography	Encryption	not planned
	Authentication	not planned

This is the current state of implemented Advertising Data:

Advertising Data	Format	Status
Service UUID	Incomplete List of 16-bit Service UUIDs	implemented
	Complete List of 16-bit Service UUIDs	implemented
	Incomplete List of 32-bit Service UUIDs	not planned
	Complete List of 32-bit Service UUIDs	not planned
	Incomplete List of 128-bit Service UUIDs	implemented
	Complete List of 128-bit Service UUIDs	implemented
Local Name	Shortened Local Name	implemented
	Complete Local Name	implemented
Flags	Flags	implemented
Manufacturer Specific Data	Manufacturer Specific Data	planned
TX Power Level	TX Power Level	planned
Secure Simple Pairing Out of Band		not planned
Security Manager Out of Band		not planned
Security Manager TK Value		not planned
Slave Connection Interval Range		not planned
Service Solicitation		not planned
Service Data		not planned
Appearance	Appearance	implemented
LE Role	LE Role	planned

This is the current state of the Link Layer implementation:

Aspect	Feature	Status
Roles	Slave Role	implemented
	Master Role	not planned
Advertising	connectable undirected advertising	implemented
	connectable directed advertising	implemented
	non-connectable undirected advertising	implemented
	scannable undirected advertising	implemented
Device Filtering		implemented
Connections	Single Connection	implemented
	Multiple Connection	not planned
Connection	Slave Latency	planned
Feature Support	LE Encryption	planned
	Connection Parameters Request Procedure	planned
	Extended Reject Indication	planned
	Slave-initiated Features Exchange	planned
	LE Ping	implemented
	LE Data Packet Length Extension	planned
	LL Privacy	not planned
	Extended Scanner Filter Policies	not planned

Pullrequests are wellcome.

Dependencies

• boost for Unittests
• CMake for build
• a decent C++ compiler supporting C++11