How to get Central name and unique UUID?

RE: How to get Central name and unique UUID?

Clonimmus74 — Mon, 03 Sep 2018 15:08:08 GMT

I used a timer and it solved the problem.

100msec wasn't enough, had to set 200msec, I have no idea why the Central is busy for so long, as I do that right after the connection had established, nothing else is executed.

RE: How to get Central name and unique UUID?

Clonimmus74 — Mon, 03 Sep 2018 06:59:13 GMT

Hi,

I tried (in BLE_GAP_EVT_CONNECTED):

do
{
err_code = sd_ble_gattc_char_value_by_uuid_read(m_conn_handle, p_uuid, p_handle_range);
}
while (NRF_ERROR_BUSY == err_code);

and I never get out of the do-while loop....

RE: How to get Central name and unique UUID?

Mttrinh — Tue, 28 Aug 2018 12:49:15 GMT

Hi,

NRF_ERROR_BUSY means that a client procedure is already in progress and you need to try again. You might need to call the function again to test if it’s ready. Adding a timer could be the solution.

You need to add the BLE_GATTC_EVT_CHAR_VAL_BY_UUID_READ_RSP event in the ble_evt_handler.

RE: How to get Central name and unique UUID?

Clonimmus74 — Sun, 26 Aug 2018 07:27:52 GMT

What do you mean by "anything else is running"? I execute the code in the BLE_GAP_EVT_CONNECTED event in ble_evt_handler after the execution of nrf_ble_qwr_conn_handle_assign.

I tried also executing the code in main, right after BLE_GAP_EVT_CONNECTED event, before any data exchange is happening.

Do I look for BLE_GATTC_EVT_CHAR_VAL_BY_UUID_READ_RSP event in ble_evt_handler() function?

Thanks.

RE: How to get Central name and unique UUID?

Mttrinh — Fri, 24 Aug 2018 10:39:10 GMT

Hi,

Error code 17 means NRF_ERROR_BUSY, have you checked if anything else is running when you call this function?

Regarding the repsonse, have a look at this message sequence chart. After calling sd_ble_gattc_char_value_by_uuid_read(and it returns success) you will receive an event BLE_GATTC_EVT_CHAR_VAL_BY_UUID_READ_RSP. You will need to handle this in the ble_evt_handler and then you can get the value from p_ble_evt->gattc_evt.params.char_val_by_uuid_read_rsp.handle_value[0].

RE: How to get Central name and unique UUID?

Clonimmus74 — Wed, 22 Aug 2018 13:55:05 GMT

I tried:

  ble_uuid_t p_uuid = {.uuid = BLE_UUID_GAP_CHARACTERISTIC_DEVICE_NAME,.type = BLE_UUID_TYPE_BLE};
  ble_gattc_handle_range_t p_handle_range = {.start_handle = 0x0001, .end_handle = 0xFFFF};

  err_code = sd_ble_gattc_char_value_by_uuid_read(m_conn_handle, &p_uuid, &p_handle_range);
  APP_ERROR_CHECK(err_code);

And received err_code = 17

RE: How to get Central name and unique UUID?

Clonimmus74 — Wed, 22 Aug 2018 12:58:00 GMT

I understand I need to use:

sd_ble_gattc_char_value_by_uuid_read

So I did:

             ble_uuid_t p_uuid = {.uuid = BLE_UUID_GAP_CHARACTERISTIC_DEVICE_NAME,.type = BLE_UUID_TYPE_BLE};

             sd_ble_gattc_char_value_by_uuid_read(m_conn_handle, &p_uuid,
            ble_gattc_handle_range_t const *  p_handle_range
            )

As you can see, I have no idea what to put in p_handle_range.

Also, where do I see the response?

RE: How to get Central name and unique UUID?

Mttrinh — Tue, 14 Aug 2018 13:27:37 GMT

Hi,

The device name of the central is contained in the device name characteristic, if it has a name. It can then be extracted through the GATT layer by discovering the service. After you have done a service discovery, you will be able to get the device name and UUID.

Also, if you are using the UART central example, you would need to add a service with a name characteristic.