Custom BLE Client with 128BIT UUID

RE: Custom BLE Client with 128BIT UUID

DougMortime — Wed, 12 Jul 2023 12:10:23 GMT

Haha no problems! Thanks for pointing me to the scanning module.

Regards,

RE: Custom BLE Client with 128BIT UUID

Vidar Berg — Wed, 12 Jul 2023 12:09:14 GMT

Hello,

I was just about to review your code. Thanks for the update!

Regards,

Vidar

RE: Custom BLE Client with 128BIT UUID

DougMortime — Wed, 12 Jul 2023 12:08:30 GMT

Hello,

Finally, tracked down the issue. It was the gatt_chrc.

params.value_handle = gatt_chrc->value_handle

Now its working as intended.

Regards,

RE: Custom BLE Client with 128BIT UUID

DougMortime — Tue, 11 Jul 2023 19:17:26 GMT

Hello Vidar,

After a long slog I finally have it connecting and discovering the service as well as the characteristic. The notification however won't come through, I've tried the peripheral on another device (iPad as client) and it works seamlessly.

I note that when I disconnect the peripheral, turn off the power, finally my notify_func gets called albeit its null.

Any thoughts at all would be appreciated greatly.

I've attached the relevant code based on your input to use the scanning module.

static struct bt_conn *default_conn;

static uint8_t notify_func(struct bt_conn *conn,
						   struct bt_gatt_subscribe_params *params,
						   const void *data, uint16_t length)
{

	printk("Notification: data %p length %u\n", data, length);
	return BT_GATT_ITER_CONTINUE;
}

static void discovery_complete(struct bt_gatt_dm *dm,
							   void *context)
{

	printk("Service discovery completed\n");

	bt_gatt_dm_data_print(dm);
	const struct bt_gatt_dm_attr *gatt_service_attr = bt_gatt_dm_service_get(dm);
	const struct bt_gatt_service_val *gatt_service = bt_gatt_dm_attr_service_val(gatt_service_attr);
	char uuid_str[37];
	bt_uuid_to_str(gatt_service->uuid, uuid_str, sizeof(uuid_str));
	printk("Discovered service %s\n", uuid_str);
	memset(uuid_str, 0, sizeof(uuid_str));

	const struct bt_uuid *chrc_ptr = BT_UUID_DECLARE_128(BT_UUID_SENSOR_INPUT1);
	bt_uuid_to_str(chrc_ptr, uuid_str, sizeof(uuid_str));
	printk("CHRC UUID %s\n", uuid_str);
	const struct bt_gatt_dm_attr *gatt_chrc_attr = bt_gatt_dm_char_by_uuid(dm, chrc_ptr);
	if (!gatt_chrc_attr)
	{
		printk("No matching characteristics found\n");
		return;
	}

	const struct bt_gatt_chrc *gatt_chrc = bt_gatt_dm_attr_chrc_val(gatt_chrc_attr);

	const struct bt_gatt_dm_attr *gatt_chrc_ccc = bt_gatt_dm_desc_by_uuid(dm, gatt_chrc_attr, BT_UUID_GATT_CCC);
	if (!gatt_chrc_ccc)
	{
		printk("CCC handle not found\n");
		return;
	}

	struct bt_gatt_subscribe_params params;
	memset(&params, 0, sizeof(params));
	params.ccc_handle = gatt_chrc_ccc->handle;
	params.value_handle = gatt_chrc_attr->handle; 
	params.value = BT_GATT_CCC_NOTIFY;
	params.notify = notify_func;

	int err = bt_gatt_subscribe(default_conn, &params);
	if (err && err != -EALREADY)
	{
		printk("Subscribe failed (err %d)\n", err);
	}
	else
	{
		printk("Subscribed\n");
	}

	bt_gatt_dm_data_release(dm);
}

Regards,

RE: Custom BLE Client with 128BIT UUID

Vidar Berg — Tue, 11 Jul 2023 12:18:39 GMT

Hello Doug,

I think it's easier to use our Scanning module with filter matching, same as we do in the central uart sample here: https://github.com/nrfconnect/sdk-nrf/blob/main/samples/bluetooth/central_uart/src/main.c#L502

[quote user=""]Now to the section where I think the issue really is, the eir_found callback function.[/quote]

I guess it fails because it does not find a matching UUID? I would suggest to print the UUIDs parsed from the adv. packets to see if the expected UUID is found our not.

Regards,

Vidar

RE: Custom BLE Client with 128BIT UUID

DougMortime — Mon, 10 Jul 2023 17:45:26 GMT

I should have been clearer, what doesn't work is that I can't seem to connect to any peripherals at all, the scanning seems to be fine.

Regards