MAC Address Incrementation Pairing issue

Question

Hi, 
 We are testing mass pairing on our windows machines, as we have seen problems with a high number of paired devices. 
 I am able to increment the mac address by using sd_ble_gap_addr_set, and saving it in a noinit ram section, and soft reseting the device. 
 I also erase bonds post reset, and have tried pre reset as well. 
 I see the advertisement on the incremented mac address, but I receive a pairing error (136 - which from what I have seen, is the result of an invalid state of the PM). What can I do to fix this? Thanks! 
 Roi

Vidar Berg · Accepted Answer

Hello, 
 Sorry for the delayed response. Have you had any progress on this issue in the meantime? The reason for the BLE_GAP_SEC_STATUS_ UNSPECIFIED error seems to be related to the fact that the peripheral keeps re-using the same IRK (identity resolving key - is exchanged during bonding procedure). Updating the IRK along with the BLE address does the trick. 
 Modified main() in ble_app_hid_keyboard to generate new random BLE address and IRK on startup: 
 /**@brief Function for application main entry.
 */
int main(void)
{
 bool erase_bonds;
 uint32_t err_code;

 // Initialize.
 log_init();
 timers_init();
 buttons_leds_init(&erase_bonds);
 // Delete bonds on startup
 erase_bonds = 1;
 power_management_init();
 ble_stack_init();
 scheduler_init();
 gap_params_init();

 uint8_t random_bytes[16];
 ble_gap_addr_t addr;
 uint8_t capacity;

 do
 {
 err_code = sd_rand_application_bytes_available_get(&capacity);
 APP_ERROR_CHECK(err_code);
 } while (capacity < 16);

 err_code = sd_rand_application_vector_get(random_bytes, sizeof(random_bytes));
 APP_ERROR_CHECK(err_code);

 err_code = sd_ble_gap_addr_get(&addr);
 APP_ERROR_CHECK(err_code);

 // Swap out 3 of the address bytes with the random bytes to make the address unique.
 addr.addr[2] = random_bytes[0];
 addr.addr[3] = random_bytes[1];
 addr.addr[4] = random_bytes[2];

 err_code = sd_ble_gap_addr_set(&addr);
 APP_ERROR_CHECK(err_code);

 gatt_init();
 advertising_init();
 services_init();
 sensor_simulator_init();
 conn_params_init();
 buffer_init();
 peer_manager_init();

 pm_privacy_params_t privacy_params;
 ble_gap_irk_t irk;

 memset(&privacy_params, 0, sizeof(privacy_params));

 privacy_params.p_device_irk = &irk;

 err_code = pm_privacy_get(&privacy_params);
 APP_ERROR_CHECK(err_code);


 //Update the local IRK
 irk.irk[2] = random_bytes[0];
 irk.irk[3] = random_bytes[1];
 irk.irk[4] = random_bytes[2];

 err_code = pm_privacy_set(&privacy_params);
 APP_ERROR_CHECK(err_code);
 // Start execution.
 NRF_LOG_INFO("HID Keyboard example started.");
 timers_start();
 advertising_start(erase_bonds);

 // Enter main loop.
 for (;;)
 {
 idle_state_handle();
 }
}

MAC Address Incrementation Pairing issue

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