BLE Service with two or more characteristic having same UUID (Reading two same temperature sensors)

[beemavishnu]

Hello,

In BLE service whether can I use same Characteristics UUID (Ex: using 0x2A6E / Temperature or 0x2A1C / Temperature measurement) with only difference in the description using "0x2901: Characteristic User Description".

Scenario is to read two same temperature sensors, at different locations on same device.

To my understanding need to use unique UUID's under same Service. In that case how to read two same temperature sensors.

In ZigBee it is possible, using unique / different Endpoint with same DeviceID. So that multiple same temperature sensors can be distinguised using unique Endpoint number.

Please let me know your inputs.

Thanks & Regards

Vishnu Beema

[tesc]

Hi,

According to the Bluetooth Core Specification v6, volume 3, part G:

"A service may have multiple characteristic definitions with the same Characteristic UUID" (section 3.3.1.) Further, "a device (...) may have multiple service definitions with the same service UUID" (section 3.1.)

This means that you can either have multiple instances of the same service (each with the given characteristic), or, you can have multiple instances of a characteristic within one single service. Please note that if you do implement an existing service (as specified by the Bluetooth SIG), then there may or may not be restrictions provided in the given Profile specification. Also, some implementations may expect only one instance of the characteristic in the service, and therefore ignore the others.

Regards,
Terje

[beemavishnu]

Hello,

Thanks you for your responce.

Bit confused with the statements

"A service may have multiple characteristic definitions with the same Characteristic UUID." This statment says, as per standards, same characteristic UUID withing service is allowed.

and with below statement

"some implementations may expect only one instance of the characteristic in the service, and therefore ignore the others"  indicating there might be some issue.

I am tyring to have cusome service having same custom characteristic UUID for both temp sensors (Ex: Two same temperature sensors at different locations on a device).

Whether "Attribute Handle" will differentiate even though if I use same characteristic UUID for two same temp sensors.

Thanks & Regards

Vishnu Beema

[tesc]

Hi,

beemavishnu said:

I am tyring to have cusome service having same custom characteristic UUID for both temp sensors (Ex: Two same temperature sensors at different locations on a device).

This should be perfectly possible, yes. Each characteristic would have their own handle and would be differentiated on the handle.

Regards,
Terje

[beemavishnu]

Thank you for your inputs