Scan UUID increase after each scanning periods

RE: Scan UUID increase after each scanning periods

huaminhtuan — Tue, 12 Sep 2017 08:47:16 GMT

Hi Sigurd, I can connect to my phone now. Thank you very much for helping me

RE: Scan UUID increase after each scanning periods

Sigurd — Mon, 11 Sep 2017 14:18:44 GMT

Since the phone uses a Private Resolvable address, the MAC that you scan will change often, and it won’t match the MAC you see in the device information in androidOS. This is the intended behavior.

Private Resolvable addresses are generated from an identity resolving key (IRK) and a random number, and they can be changed often (even during the lifetime of a connection) to avoid the device being identified and tracked by an unknown scanning device.

RE: Scan UUID increase after each scanning periods

huaminhtuan — Mon, 11 Sep 2017 13:58:09 GMT

I find the "Phone Bluetooth MAC" in the device information in andriod OS. The "Scanned MAC", I get it from advertising report and I print it in the console

RE: Scan UUID increase after each scanning periods

Sigurd — Mon, 11 Sep 2017 12:10:15 GMT

nrf_sdh_ble_evts_poll is a void function that should not return any values.

Is the Scanned MAC the one you get from the advertising report ? Where the you find the "Phone MAC" ?

RE: Scan UUID increase after each scanning periods

huaminhtuan — Mon, 11 Sep 2017 09:36:03 GMT

I run debug and it shows that it is connect successfully to target, after that, the program jumps to function nrf_sdh_ble_evts_poll and then it return error code 0x57D.

Could you please explain me why the first bit of each byte in the scanned MAC address is shifted to the last position.

Phone MAC: 11100100-01011000-10111000-00101111-01010100-00000100

Scanned MAC: 00001000-10101000-01011110-01110001-10110000-11100100

RE: Scan UUID increase after each scanning periods

Sigurd — Mon, 11 Sep 2017 09:27:22 GMT

Have you already connected to another device maybe? Are you getting the "Connecting to target.." printed on the Segger RTT log ?

RE: Scan UUID increase after each scanning periods

huaminhtuan — Mon, 11 Sep 2017 09:13:52 GMT

Hi Sigurd, When I try to connect to the scanned MAC address (00001000-10101000-01011110-01110001-10110000-11100100), the function sd_ble_gap_connect return error code 18, which is

#define NRF_ERROR_CONN_COUNT                  (NRF_ERROR_BASE_NUM + 18) ///< Maximum connection count exceeded.

I checked that the following definition is set:

// <o> NRF_SDH_BLE_PERIPHERAL_LINK_COUNT - Maximum number of peripheral links.
#ifndef NRF_SDH_BLE_PERIPHERAL_LINK_COUNT
#define NRF_SDH_BLE_PERIPHERAL_LINK_COUNT 1
#endif

// <o> NRF_SDH_BLE_CENTRAL_LINK_COUNT - Maximum number of central links.
#ifndef NRF_SDH_BLE_CENTRAL_LINK_COUNT
#define NRF_SDH_BLE_CENTRAL_LINK_COUNT 1
#endif

// <o> NRF_SDH_BLE_TOTAL_LINK_COUNT - Maximum number of total concurrent connections using the default configuration.
#ifndef NRF_SDH_BLE_TOTAL_LINK_COUNT
#define NRF_SDH_BLE_TOTAL_LINK_COUNT 2
#endif

Can you help me please? Thanks

RE: Scan UUID increase after each scanning periods

huaminhtuan — Mon, 11 Sep 2017 05:02:10 GMT

Hi Sigurd,

I get MAC address from my phone, but it is weird. The first bit of each byte is shifted to the last position.

Phone MAC: 11100100-01011000-10111000-00101111-01010100-00000100

Scanned MAC: 00001000-10101000-01011110-01110001-10110000-11100100

RE: Scan UUID increase after each scanning periods

Sigurd — Fri, 08 Sep 2017 12:01:25 GMT

It's in the ble_gap_evt_adv_report_t->peer_addr->addr.

If we take a look at the original ble_app_uart_c code, we are first looking for the Nordic UART Service UUID, and if the UUID is found we connect. If the connect request is successful, we print the Bluetooth address of the peer device.

Code snippet:

case BLE_GAP_EVT_ADV_REPORT:
    {
        const ble_gap_evt_adv_report_t * p_adv_report = &p_gap_evt->params.adv_report;

        if (is_uuid_present(&m_nus_uuid, p_adv_report))
        {

            err_code = sd_ble_gap_connect(&p_adv_report->peer_addr,
                                          &m_scan_params,
                                          &m_connection_param,
                                          CONN_CFG_TAG);

            if (err_code == NRF_SUCCESS)
            {
                // scan is automatically stopped by the connect
                err_code = bsp_indication_set(BSP_INDICATE_IDLE);
                APP_ERROR_CHECK(err_code);
                NRF_LOG_INFO("Connecting to target %02x%02x%02x%02x%02x%02x\r\n",
                         p_adv_report->peer_addr.addr[0],
                         p_adv_report->peer_addr.addr[1],
                         p_adv_report->peer_addr.addr[2],
                         p_adv_report->peer_addr.addr[3],
                         p_adv_report->peer_addr.addr[4],
                         p_adv_report->peer_addr.addr[5]
                         );
            }
        }

RE: Scan UUID increase after each scanning periods

huaminhtuan — Fri, 08 Sep 2017 03:20:33 GMT

Hi Sigurd, sorry but I'm not understand. Could you explain more detail please? Where can I get the phone 6-byte MAC address? Is it in the field ble_gap_evt_adv_report_t->peer_addr->addr or ble_gap_evt_adv_report_t->direct_addr->addr? Thanks for helping me!

RE: Scan UUID increase after each scanning periods

Sigurd — Thu, 07 Sep 2017 08:03:38 GMT

Yes, you should be able to connect to the phone.

Q:how can I know that advertising device is my phone or another one?

A: You can identify the phone by its 6-byte MAC address. The phone uses a Private Resolvable address. So you have to pair/bond with the phone. See this post for information about BLE addresses.

RE: Scan UUID increase after each scanning periods

huaminhtuan — Wed, 06 Sep 2017 16:20:27 GMT

So, how can I know that advertising device is my phone or another one? And in this case, can I use sd_ble_gap_connect function to connect with mine?

RE: Scan UUID increase after each scanning periods

Sigurd — Wed, 06 Sep 2017 15:33:16 GMT

Yes, when you make the phone "visible" it will advertise. I tested this on my Samsung phone, but it did not contain any UUID, only the "ManufacturerSpecificData" field that told me that it was a Samsung phone.

So it’s expected and correct that the sd_ble_uuid_decode() returns NRF_ERROR_NOT_FOUND in this case.

RE: Scan UUID increase after each scanning periods

huaminhtuan — Wed, 06 Sep 2017 14:23:16 GMT

Hi Sigurd, I turn Bluetooth on my cell phone on and I make it "visible" from another device. Does that mean my Phone is advertising? I tried nRF Connect adveriser function, but it showed me a message that the advertiser function is not available on my device.

RE: Scan UUID increase after each scanning periods

Sigurd — Wed, 06 Sep 2017 10:39:24 GMT

It's not certain that you have a UUID configured in the advertising packet. What app do you use on the phone to use it as peripheral? What UUID are you looking for? and why are you doing this when the field type is BLE_GAP_AD_TYPE_MANUFACTURER_SPECIFIC_DATA?

RE: Scan UUID increase after each scanning periods

huaminhtuan — Tue, 05 Sep 2017 02:44:17 GMT

Hi Sigurd, my central device is nRF52832 chip and my peripheral device is my cell phone, so what is the UUID of my cell phone, which is being scanned, looks like? Is it a 128 bit UUID with type BLE_GAP_AD_TYPE_MANUFACTURER_SPECIFIC_DATA (type code is 255)?

RE: Scan UUID increase after each scanning periods

Sigurd — Mon, 04 Sep 2017 11:49:49 GMT

Hi,

You are getting error code 5(NRF_ERROR_NOT_FOUND) from the function sd_ble_uuid_decode(),so that is probably what is causing this. You are not actually getting a valid UUID.

Take a look at this post where this issue was solved.