Question about read operation

[Artem Zemlyanukhin]

Hello! I want to ask about read operation on nrf51822. In your examples, as I understand, BT stack handles Read Request automatically and then sends Read Response. The value that I try to read is Attribute in Service Table (for example only read permission without notify/indicate). To keep this value actual I must call sd_ble_gatts_value_set() when it changes. Can I set attribute value only during processing Read Request? Because I don't want to track all the time this value. I only need send actual value in Read Response after Read Request. Thank you for answer!

Artem Zemlyanuklhin Woodenshark

[Carles]

Hi there,

Yes, you can.

You can use the authorization mechanism on any particular attribute to achieve this. Set the read authorization bit (rd_auth in ble_gatts_attr_md_t) when adding your characteristic to the attribute table and you will get a BLE_GATTS_EVT_RW_AUTHORIZE_REQUEST event every time a remote peer tries to read that characteristic, and you can reply by calling the sd_ble_rw_authorize_reply() with the value you want.

Refer to the SoftDevice documentation for further details.

Regards,

Carles

[Ole Morten]

Once you have enabled authorization for a characteristic, all reads will be authorized, so this shouldn't be a problem.

[Artem Zemlyanukhin]

ok, thanks for response!

[Ole Morten]

No problem. Feel free to accept the answer, so that it's easier to find for others. :-)

[Ole Morten]

Done. Didn't notice it was posted with an anonymous user. Thanks!

[kchuva]

Dear Ole Morten, why reason to this implementation of SoftDevice? If I want to Read value which changes in unknown time I can read it only With Authorization. So, I will spend more time to read one characteristic. Why Read Without Authorization Event don't pass to Application layer?