how can I use GATT_Notification command with BTool - bluetooth-lowenergy

Question

im using BTool to send commands to CC2540 bluetooth module. I want to get notifications. when I send notification command, btool displayed the sent command
[43] : <Tx> - 11:11:47.051
-Type : 0x01 (Command)
-OpCode : 0xFD9B (GATT_Notification)
-Data Length : 0x06 (6) byte(s)
ConnHandle : 0x0000 (0)
Authentic : 0x00 (0) (No)
Handle : 0x1B00 (6912)
Value : 00:50
Dump(Tx):
0000:01 9B FD 06 00 00 00 1B 00 50
the values of the Handle (temperature characteristic) and connHandle are correct, but I dont get any response from the server. is there any prior configuration to perform, like enabling notifications somewhere?

Answer 1

You need to enable notification for the characteristic. First you need to query for the client characteristic configuration uuid:
08 1B 00 1C 00 02 29
where first byte is the op read request, next two bytes are you handle id, subsequent two bytes are the range limit (handle id + 1), and the last two bytes are the GATT_CLIENT_CHARAC_CFG_UUID filter. You'll get a response similar to this:
09 04 LL HH 00 00
where the first byte is the response (read by type response), next byte is payload length, LL HH is the configuration characteristic handle, and the last two bytes are it's value.
At this step you can enable the notification by writing a 0x0001 to this handle id:
12 LL HH 01 00
At his point the notification for you characteristic should be enabled.