bluetooth - Which BluetoothLE handle do I need to write on to enable notifications?

Question

This is my first shot working with bluetooth and I'm confused about which channel I should be sending my write packet to enable notifications. I'm working with the Fitness Machine 0x1826 service and I'm trying to get the data from the 0x2AD2 characteristic, specifically the 0x0030 handle.

When I run "sudo gatttool -t random -b [MAC ADDRESS] -I --char-write-req -a 0x0030 - 0300 --listen" I get no response so I'm led to believe that I'm sending the packet to the wrong handle, as the device should be sending notifications with my actions.

Thanks for any help!

Answer 1

You should send your write packet to Client Characteristic Configuration Descriptor (CCCD), which has a UUID 0x2902. You first need to find the handle of that CCCD within the fitness machine service. You can find more information here:-

• Reading Thermometer Data with BlueZ
• Bluetooth Low Energy: listening for notifications/indications in linux

However, as ukBaz mentioned, gatttool is deprecated so you should look into using bluetoothctl instead. More information on using bluetoothctl as a gatt client is found here:-

• bluetoothctl write on descriptor to enable notification
• Using acquire-write and acquire-notify in bluetoothctl