why i am getting pairing rejected by nordic _uart

[ps_anu]

hi..folks 

wish you happiee new year

i am using nrf52832 whille i tried to pair my device with my android , i am getting an error message " pairing rejected by nordic_uart "  why?

[Kenneth]

I do believe the example you refer to does not support pairing and bonding, refer to:

        case BLE_GAP_EVT_SEC_PARAMS_REQUEST:
            // Pairing not supported
            err_code = sd_ble_gap_sec_params_reply(m_conn_handle, BLE_GAP_SEC_STATUS_PAIRING_NOT_SUPP, NULL, NULL);
            APP_ERROR_CHECK(err_code);
            break;

If you want to support pairing and bonding, then you need to use an example that have peer manager.

[Priyajit]

While I am going to pair with my android 9 Asus mobile phone with SDK 17 nRF52840. It in my mobile showing "Pairing rejected by Nordic_HRM". After that  I have added a some code line to

static void peer_manager_init(bool erase_bonds);

sec_param.bond = false;

sec_param.mitm = false;

sec_param.lesc = 0;

sec_param.keypress = 0;

sec_param.io_caps = BLE_GAP_IO_CAPS_NONE;

sec_param.oob = false;

sec_param.min_key_size = 7;

sec_param.max_key_size = 16;

sec_param.kdist_own.enc = 0;

sec_param.kdist_own.id = 0;

sec_param.kdist_peer.enc = 0;

sec_param.kdist_peer.id = 0;

And getting same "Pairing rejected by Nordic_HRM"

After that I have added this code,

sec_param.bond = true;
sec_param.mitm = false;
sec_param.lesc = 0;
sec_param.keypress = 0;
sec_param.io_caps = BLE_GAP_IO_CAPS_NONE;
sec_param.oob = false;
sec_param.min_key_size = 7;
sec_param.max_key_size = 16;
sec_param.kdist_own.enc = 1;
sec_param.kdist_own.id = 1;
sec_param.kdist_peer.enc = 1;
sec_param.kdist_peer.id = 1;

And getting same "Pairing rejected by Nordic_HRM"

Please give some solution.

[Kenneth]

Presuming your change doesn't give any error code, then I suspect it may be related to HRM already have a bond, thereby doesn't want to allow re-bonding with the same peer. 

Typically the application can allow re-pairing by adding the following in pm_evt_handler() in main.c:

case PM_EVT_CONN_SEC_CONFIG_REQ:
{
// Allow or reject pairing request from an already bonded peer.
pm_conn_sec_config_t conn_sec_config = {.allow_repairing = true};
pm_conn_sec_config_reply(p_evt->conn_handle, &conn_sec_config);
} break;

Though, be aware that the user should somehow control this (e.g. by the user for instance press a pairing button), because always allowing re-pairing should be considered an security issue.

If this isn't the problem, then I would like a on-air sniffer log (e.g. from nRF sniffer) so I can see the actual on-air error.