Advertising data via BLE GATT SERVICE with bl_notify_gatt() function

RE: Advertising data via BLE GATT SERVICE with bl_notify_gatt() function

Vidar Berg — Tue, 09 Apr 2024 13:20:07 GMT

Hi Ossian,

I see now that you are also missing the CCCD descriptor needed by the client to enable notifications. Please try changing your service declaration like this:

static void tx_ccc_cfg_changed(const struct bt_gatt_attr *attr,
				  uint16_t value)
{
	if (value == BT_GATT_CCC_NOTIFY) {
		printk("Notifications enabled\n");
	}
	else {
		printk("Notifications disabled\n");
	} 
}

BT_GATT_SERVICE_DEFINE(custom_srv,
        BT_GATT_PRIMARY_SERVICE(BT_UUID_MY_CUSTOM_SERVICE),
        BT_GATT_CHARACTERISTIC(BT_UUID_MY_CAPACITANCE_CHRC, BT_GATT_CHRC_READ | BT_GATT_CHRC_NOTIFY, BT_GATT_PERM_READ, my_read_capacitance_function, NULL, NULL),
	BT_GATT_CCC(tx_ccc_cfg_changed,
			       BT_GATT_PERM_READ | BT_GATT_PERM_WRITE),
        BT_GATT_CHARACTERISTIC(BT_UUID_MY_BATV_CHRC, BT_GATT_CHRC_READ, BT_GATT_PERM_READ, my_read_battery_status_function, NULL, NULL)
);

Best regards,

Vidar

RE: Advertising data via BLE GATT SERVICE with bl_notify_gatt() function

ossian33 — Tue, 09 Apr 2024 13:13:37 GMT

Hi Vidar,

I tried to swap to '&custom_srv.attrs[2]', but i still get the error code '-22' after calling 'int ret = bt_gatt_notify(conn, &custom_srv.attrs[2], &picoFarads_32, sizeof(picoFarads_32));'. Could it be that i have missed something when defining the notify functionality?

Best regards,
Ossian

RE: Advertising data via BLE GATT SERVICE with bl_notify_gatt() function

Vidar Berg — Tue, 09 Apr 2024 12:21:59 GMT

Hello,

Please try to change the '&custom_srv.attrs[1]' parameter to '&custom_srv.attrs[2]' so it points to your characteristic in the service structure and not the service itself.

Best regards,

Vidar