Difference between BLE "Characteristic Declaration" and "Client Characteristic Configuration"

[beemavishnu]

Hello,

I have a basic queries on BLE.

"Characteristic Properties" of "Characteristic Declaration" with UUID 0x2803 has Read, Write, Notify and Indicate. At the same time "Client Characteristic Configuration" Descriptor (CCCD) with UUID 0x2902 too has Notify and Indication.

What is the difference between Notification in UUID 0x2803 and Notification in UUID 0x2902.

Thanks & Regards

Vishnu Beema

[AndreasF]

Hi Vishnu Beema.

UUID 0x2803 and UUID 0x2902 are the UUIDs for Characteristic Declaration (0x2803) and Descriptor Declaration (0x2902).

I recommend that you take a look at the tutorial Bluetooth low energy Characteristics, a beginner's tutorial, it is all explained there.

Best regards,

Andreas

[beemavishnu]

Hello Andreas,

Thank you for the reference. I have gone through the reference. As per link under "Characteristic Declaration" 

"properties describe how the characteristic value can be interacted with". So I can keep either "Notify" or "Indicate" as Characteristic Properties for specific attribute.

But apart from this why there is one more "Client Characteristic Configuration" Descriptor CCCD which will tell the same either to enable "Notify" or "Indicate".

Thanks & Regards

Vishnu Beema

[AndreasF]

Hi Visnu Beema.

If you use the Characteristic Declaration for "Notify" or "Indicate", you also have to enable the use of them. This is done by enable "Notify" or "Indicate" in the "Client Characteristic Configuration" Descriptor (CCCD).

Chapters to read in the Bluetooth Core Spec v.5 is:

3.3.1 Characteristic Properties
3.3.3.3 Client Characteristic Configuration

Both in Vol 3, Part G

Best regards,

Andreas