Direct advertising to any device

[Pureer]

Hello everyone.

There have a scenario, nrf52832 starts a direct advertising , but the dest ble device is not bonded(it could be any other central device), when the dest ble device receive the direct advertising it should initiate the connection to advertiser.

Can it work?

[Simon]

If the central device uses a Random Private Resolvable address, this is not possible, since the device advertising doesn't have the IRK. However, what is the goal of your project? Could you elaborate? Maybe whitelisting could solve your problems?

Best regards,

Simon

[Pureer]

**The central device is Android. Peripheral device is nrf52832.

**The nrf52832 will get any infomations about central device by other way(actually central will produce ultrasonic,nrf52 will decode it) .Becase there are so many nrf52 peripherals,and this way is more convenient than search manually.

**I want some of specific nrf52s can advertising to central,central will initiate connect,and I don't want central connect to other peripheral or peripheral be connected by other central.

**The specific nrf52s advertising can be hidden to other central is better.

Sorry ,my English is not good , I hope I have written clearly.

Can whitelisting do work with no bonding ?  Could you please tell me which api it is ?

[Simon]

Yes, it is possible for the central (Android device) to whitelist the peripheral (nRF52832) without bonding with it (See Hung's answer). You could use the BLE Heart Rate Collector Example as a guide for how to implement whitelisting.

Best regards,

Simon

[Pureer]

Simon，I think if the central device is Android device,to edit the whitelist manually also need the IRK.Am I right?

[Simon]

Yes, you need the IRK in order to convert the random address into the real address and identify the device.

[Pureer]

//Global var
ble_gap_id_key_t oneplus3_key = {
    .id_addr_info={
        0,
        BLE_GAP_ADDR_TYPE_RANDOM_STATIC,
        {0x76,0x53,0xd6,0xfb,0xee,0xc0},          //one_plus3  android phone
    }
};

//........................
//........................
//........................
//........................
//........................
//........................

void init_advertising(void){
..................................................................
..................................................................
    uint8_t *oneplus3_irk_string = "076b01ad29fcbb56bda76d3c9adb0ec0";  // adb shell ,/data/misc/bluedroid/bt_config.config grep "LOCAL_IRK"

    uint8_t temp[2];
    uint8_t *ptr = NULL;
    unsigned long ret = 0;

    for (int i = 0,j=0; i < BLE_GAP_SEC_KEY_LEN;i++,j+=2)
    {
        memmove(temp,&oneplus3_irk_string[j],sizeof(uint8_t)*2);
        ret = strtoul(temp, &ptr, 16);

        oneplus3_key.id_info.irk[i] = (uint8_t)ret;
    }
    // The irk is right ,I have test it in fast advertising with pm_address_resolve();
..............................................................
..................................................................



static void on_adv_evt(ble_adv_evt_t ble_adv_evt){
................................................
        case BLE_ADV_EVT_WHITELIST_REQUEST:
        {
            ble_gap_id_key_t* key_list[BLE_GAP_DEVICE_IDENTITIES_MAX_COUNT];
            memset(key_list,0,BLE_GAP_DEVICE_IDENTITIES_MAX_COUNT*sizeof(int));
            key_list[0] =    &oneplus3_key;
            sd_ble_gap_device_identities_set(key_list,NULL,1);

            ble_gap_addr_t const* whitelist_addrs_gap[BLE_GAP_WHITELIST_ADDR_MAX_COUNT];

            ble_gap_addr_t whitelist_addrs[BLE_GAP_WHITELIST_ADDR_MAX_COUNT];
            ble_gap_irk_t  whitelist_irks[BLE_GAP_WHITELIST_ADDR_MAX_COUNT];
            uint32_t       addr_cnt = BLE_GAP_WHITELIST_ADDR_MAX_COUNT;
            uint32_t       irk_cnt  = BLE_GAP_WHITELIST_ADDR_MAX_COUNT;

            whitelist_addrs_gap[0] = &oneplus3_key.id_addr_info;
            memmove(&whitelist_addrs[0],&oneplus3_key.id_addr_info,sizeof(ble_gap_addr_t));
            memmove(&whitelist_irks[0],&oneplus3_key.id_info,sizeof(ble_gap_irk_t));
            addr_cnt = 1;
            irk_cnt = 1;

            err_code = sd_ble_gap_whitelist_set(whitelist_addrs_gap, 1);
            APP_ERROR_CHECK(err_code);

            // Apply the whitelist.
            err_code = ble_advertising_whitelist_reply(&m_advertising,
                                                       whitelist_addrs,
                                                       addr_cnt,
                                                       whitelist_irks,
                                                       irk_cnt);
            APP_ERROR_CHECK(err_code);
        }
        break;
......................................................

Simon,Thank you for your reply.Could you check the my code snippets? I do the whitelist and nrfConnect can't establish the connection.