Zephyr BLE How a central device acknowledges an indication

RE: Zephyr BLE How a central device acknowledges an indication

wliao — Wed, 06 Sep 2023 15:42:09 GMT

It works after using the destroy callback instead. Thanks!

RE: Zephyr BLE How a central device acknowledges an indication

AHaug — Wed, 06 Sep 2023 07:08:35 GMT

Hi,

Apologies for the delayed response. I had to double check something. So to clarify the difference in how notifications and indications works w.r.t. acks:

With Notification, you have a callback from the controller when the notification packet is sent to the peer bt_gatt_notify_cb
With indications, you have the same + another callback that is coming as an ack from the peer. This callback is called destroy (confusing name)

Look into the zephyr\samples\bluetooth\peripheral_ht\src\hts.c

ind_params.attr = &hts_svc.attrs[2];

ind_params.func = indicate_cb;

ind_params.destroy = indicate_destroy;

ind_params.data = &htm;

ind_params.len = sizeof(htm);



if (bt_gatt_indicate(NULL, &ind_params) == 0) {

indicating = 1U;

}

As you can see, indicate_cb will be call immediate when the radio sent the indication to the peer. and indicate_destroy will be called when the peer acknowledged it

Let me know if this makes things more clear for you!

Kind regards,
Andreas

RE: Zephyr BLE How a central device acknowledges an indication

wliao — Tue, 05 Sep 2023 17:56:46 GMT

Is the API function bt_gatt_write_without_response used to send the confirmation of acknowledging the indication? If so, what is the use case of the callback function specified in the struct bt_gatt_indicate_params when the indication is generated? It seems the callback function never being called.

RE: Zephyr BLE How a central device acknowledges an indication

wliao — Fri, 01 Sep 2023 13:25:09 GMT

Hi Andreas,

Our application needs both notification and indication.

As to handling the acknowledge, which API function should be used?

And what the callback function func (bt_gatt_indicate_func_t) of the struct bt_gatt_indicate_params is used for, i.e. when this callback gets called anyway?

Thanks!

RE: Zephyr BLE How a central device acknowledges an indication

AHaug — Fri, 01 Sep 2023 12:08:26 GMT

Hi,

You are correct, for indications you will need to handle the acknowledge on the application layer.

However, based on your description, I suspect you might be interested in Notifications instead? Notifications does not require the acknowledge on application layer

Kind regards,
Andreas