RTOS/LAUNCHXL-CC1352R1: Coupling Between Attribute Permissions and Characteristic Properties

Mehmet Cagri Kose

Part Number: LAUNCHXL-CC1352R1
Other Parts Discussed in Thread: BLE-STACK

Tool/software: TI-RTOS

According to the Bluetooth Core Spec 5.0, every attribute has attribute permission and every characteristic(group of related attributes) has characteristic properties. Focusing on "characteristic value attribute", it seems to me that attribute permission has final authority on what can be done with that attribute and characteristic properties are just suggestions. I am ignoring authentication/authorization/encrpytion based read permits and focusing on pure read permission and read property. For example;

CHAR. VALUE ATT PERM    |     CHAR. PROPERTY      |     REQUEST/RESPONSE 
PERMIT_READ                                 PROP_READ             Client can send read request to value and server responds with the value
PERMIT_READ                                 PROP_NONE             Client does not know it can send read request and no transaction happens
PERMIT_NONE                                 PROP_READ             Server lies about char. value(inconsistent permit and properties). Client sends read request for char. value and server responds with error
PERMIT_NONE                                 PROP_NONE             Nothing happens

Am I understanding the relationship between permission and property correctly ?

over 7 years ago

0 Marie H over 7 years ago

TI__Guru* 82121 points

Hi Mehmet,

I don't think you have 100% the whole picture yet. Did you see Simplelink Academy? You should check out the BLE Custom Profile lab: dev.ti.com/.../

0 Sean2 over 7 years ago

TI__Mastermind 33460 points

Hello,

The properties are what is displayed in the characteristic declaration in the GATT table of the server device.
These properties are readable by any peer device doing GATT discovery, they will inform the peer device what operations are possible on that characteristic.

The permissions are internal to the BLE-Stack. These are not readable by the peer device. As you say, these are the ones that are checked inside the stack. However, in practice the permissions and properties should match to prevent issues with peer devices.

We explain more here:
dev.ti.com/.../

0 Mehmet Cagri Kose over 7 years ago

Intellectual 405 points

Thanks for both of the answers. I will be reading them.

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RTOS/LAUNCHXL-CC1352R1: Coupling Between Attribute Permissions and Characteristic Properties