Search a BLE device by MAC address

[BMG]

Hello,

I have 2 pieces of Sparkfun nrf52840 mini boards. On the first board, I uploaded the code from '\nRF5_SDK_15.0.0_a53641a\examples\ble_central\ble_app_multilink_central\' and on the second board, the code from 'nRF5_SDK_15.0.0_a53641a\examples\ble_peripheral\ble_app_blinky\'. I know that the central board is searching the peripheral by 'Nordic_Blinky' name. Instead of searching by name, I want to search by the MAC address. Is this possible?

What functions have to be modified to do this or do you have an example code?

Thank you.

[TomWS]

I believe you want to change ...SCAN_NAME_FILTER to ...SCAN_ADDR_FILTER in two places. See nrf_ble_scan.h.

Also, add a new variable with the target MAC as a ble_gap_addr_t.

UPDATED: corrected target MAC type per Amanda Hsieh's reference below.

[Amanda Hsieh]

Yes, as Thomas Studwell's suggestion. Please also be aware of the mac address display order as this post described.

-Amanda H.

[BMG]

Thank you for the answer. I've done the changes written in the post above, but the central device doesn't find the peripheral device. I've tried with the flipped order of the MAC address and also with the normal order. Nothing works.

I think it's something wrong with this code:

static ble_gap_addr_t m_target_periph_addr =

{

    .addr_type = BLE_GAP_ADDR_TYPE_RANDOM_STATIC,

    .addr      = {0x1C, 0xC6, 0x75, 0xED, 0xE8, 0xC1} // This matches what nRF Connect shows via Scan, for peripheral

};

...

static void scan_init(void)

{

    ret_code_t          err_code;

    nrf_ble_scan_init_t init_scan;

    memset(&init_scan, 0, sizeof(init_scan));

    init_scan.connect_if_match = true;

    init_scan.conn_cfg_tag     = APP_BLE_CONN_CFG_TAG;

    err_code = nrf_ble_scan_init(&m_scan, &init_scan, scan_evt_handler);

    APP_ERROR_CHECK(err_code);

    err_code = nrf_ble_scan_filter_set(&m_scan,SCAN_ADDR_FILTER,m_target_periph_addr.addr);

    APP_ERROR_CHECK(err_code);

****

    err_code = nrf_ble_scan_filters_enable(&m_scan, NRF_BLE_SCAN_ADDR_FILTER, false);

    APP_ERROR_CHECK(err_code);

}

After line ****, the blue led is blinking. I don't know if it's a reset or not.

[Amanda Hsieh]

Hi, 

BMG said:

.addr      = {0x1C, 0xC6, 0x75, 0xED, 0xE8, 0xC1} // This matches what nRF Connect shows via Scan, for peripheral

If the mac address is C1:E8:ED:75:C6:1C, the order in .addr is correct. 

It seems scan_init() lost the scan parameters. Could you try to add them? You could refer to the scan_init() inside of  <nRF5_SDK>\examples\ble_central\ble_app_hrs_c

-Amanda H.

[BMG]

Thank you, Amanda. I solved my problem by modifying the 'nRF5_SDK_15.3.0_59ac345\examples\ble_central\ble_app_multilink_central\sparkfun_nrf52840_mini\s140\config\sdk_config.h' parameter NRF_BLE_SCAN_ADDRESS_CNT to 1 instead of 0 as it was.

I got the reset because there is a check in nrf_ble_scan.c file, nrf_ble_scan_filter_set function: NRF_BLE_SCAN_ADDRESS_CNT >0 and this was the problem.

Now everything works.