develop BLE peripheral using C on intel edison

Question

I am trying to develop a bluetooth LE peripheral in intel-edison, by using C library. The device should be able to :

1. advertise (GAP)
2. accept connection (GAP)
3. support custom GATT service, simply read/write value of characteristic.

I try to use HCI and bluez to implement this. bluez-experiments, intel-edison-playground, which demonstrate how to advertise and scan, can be compiled and run on edison. BLE advertising and scanning do work.

But I have hard time to figure out how to accept connection and support GATT service. I try to search on goolge about the HCI document but have no luck. Can someone provide a snippet of code (c or pseudo or a description)?

Thank you so much!
Andrew

Answer 1

If you download the bluez source you'll find documentation on the hci protocol in /doc/mgmt-api.txt. I'm not using the hci interface myself, and I'm not sure if the developers intend for implementors to use this interface to implement peripherals, so I'm not sure how well this will work.

I went with the DBus API approach for my project, which is outlined in /doc/gatt-api.txt and /doc/advertising-api.txt. This approach involves writing a program which creates DBus objects which support specific org.bluez DBus interfaces (GattService1 which contains GattCharacteristic1 and GattDescriptor1) and the ObjectManager interface to expose everything to bluez. You then use LEAdvertisment1 to define what is advertised and register the advertisement using the LEAdvertisingManger1 interface on the adapter.

I used Qt to simplify the DBus communication parts.

The DBus API for BLE on bluez is still in heavy development, and not all features are supported (I still haven't found a way to start and stop advertising, for example). 5.31 contains a lot of added supported and some critical bug fixes for descriptors, but requires a newer kernel.