Bluez BLE Connection Linux

Question

I'm very new to Linux and Bluetooth development, and I'm unsure of the difference between sudo hcitool lecc <bdaddr> and sudo gatttool -b <dbaddr> -I ? I don't require any of the GATT services; I just want a connection between the two devices.

I'm looking at vaguely following this widely referred to tutorial , and am looking at adapting the cmd_lecc method in Bluez /tools/hcitool.c, but I am unable to connect to my BLE device using hcitool lecc .

When I connect using gatttool , I am able to connect successfully, however using hcitool lecc returns the error 'Could not create connection: Connection timed out', and no connection is made to the BLE device. However, running sudo hcitool con to show active connections shows that there is one: 'Unknown handle 0 state 2 lm SLAVE'. If it's failing to make the connection, why is it then registering the connection as active in hcitool ?

My question therefore is threefold:

1. What is the difference between the two commands?
2. Would gatttool be suitable for my purpose, or should I work out what's not working with hcitool (following something like this ?
3. Why does sudo hcitool lecc <bdaddr> partially connect, even when it times out?

Many thanks.

Answer 1

hcitool lecc <bdaddr> creates a connection and returns a handle, while gatttool -b <bdaddr> -I only opens an interactive terminal with an interface bound to the address but not yet connected. To connect using the gatttool command you must then enter connect , which will most likely also fail.

I would suggest looking at how hcitool connects for writing your own code as all of gatttool simply is a wrapper around the same process that hcitool uses, but its wrapper is not available unless you copy its code.

lastly, the handle 0 that hcitool is reporting is an invalid handle left from trying to connect, because as far as I've seen all valid handles are greater than 0.