Get connected device name in Generic Access Service from ble central

[HDuc]

Hi all,

I would like to get the complete name from the connected peripheral by reading the device name characteristic (0x2A00) in the Generic Access Service (0x1800). I am using SDK 15.2.0 with soft device s132 v6.1.1.

I have tried to call sd_ble_gattc_char_value_by_uuid_read in BLE_GAP_EVT_CONNECTED event, and then get the device name through p_ble_evt->evt.gattc_evt.params.char_val_by_uuid_read_rsp.handle_value in BLE_GATTC_EVT_CHAR_VAL_BY_UUID_READ_RSP event. But it never runs inside the event BLE_GATTC_EVT_CHAR_VAL_BY_UUID_READ_RSP.  I have tested another way by using p_ble_evt->evt.gatts_evt.params.write.data but it didn't get the device name.

So I would like to know how I can do that.

Many thanks in advance.

[Simon]

Does sd_ble_gattc_char_value_by_uuid_read(..) return NRF_SUCCESS? If it does, could you provide a sniffer trace? If not, what does it return?

Best regards,

Simon

[Andy]

I did this once by discovering the characteristic using the discovery module, storing the value handle and then calling sd_ble_gattc_read() using that value handle. It worked like a charm.

[HDuc]

Hi Simon,
Thank for your reply. I haven't used sniffer, so I will try later. Is there any other way to check it

[HDuc]

Hi Andy,
Thank for your reply. Could you explain more detail about how you do.
What are the references I must put in "handle" and "offset".
Where I have to call sd_ble_gattc_read(), in BLE_GAP_EVT_CONNECTED event or in EVT_DISCOVERY_COMPLETE event.
And how to get the value.
Many thanks in advance.

[Andy]

On your discovery event handler you do this:

if ((p_evt->evt_type == BLE_DB_DISCOVERY_COMPLETE) &&
	(p_evt->params.discovered_db.srv_uuid.uuid == gap_profile_s_uuid.uuid) &&
	(p_evt->params.discovered_db.srv_uuid.type == gap_profile_s_uuid.type)) {

	NRF_LOG_INFO("Found GAP profile service");

	// Find the CCCD Handles of the device name characteristic
	for (uint8_t i = 0; i < p_evt->params.discovered_db.char_count; i++) {
		if ((p_evt->params.discovered_db.charateristics[i].characteristic.uuid.uuid == device_name_c_uuid.uuid) &&
			(p_evt->params.discovered_db.charateristics[i].characteristic.uuid.type == device_name_c_uuid.type)) {

			NRF_LOG_INFO("Found device name characteristic");
			device_name_handle = p_evt->params.discovered_db.charateristics[i].characteristic.handle_value;

			// Break out of for loop
			break;
		}
	}
}

Then you can use the device_name_handle in sd_ble_gattc_read(). In the offset just write 0. Where you call sd_ble_gattc_read() is up to you, and it doesn't really matter.

To get the device name data, you need to do this in you BLE event handler:

case BLE_GATTC_EVT_READ_RSP:;
	ble_gattc_evt_read_rsp_t const * p_read_rsp = &p_ble_evt->evt.gattc_evt.params.read_rsp;

	NRF_LOG_INFO("Read length: %d, Read offset: %d", p_read_rsp->len, p_read_rsp->offset);

	// We are reading the device name
	if (p_read_rsp->handle == device_name_handle) {
		for (uint8_t i = 0; i < p_read_rsp->len; i++) {
			device_name[i + p_read_rsp->offset] = p_read_rsp->data[i];
		}
		device_name_length = p_read_rsp->len + p_read_rsp->offset;
	}
	break;