Error 13313 [Unknown error code] BLE cannot re-connect after disconnection

Question

Hi, I'm using nRF52805.

My BLE code could connect & communicate data perfectly for the first time. After the disconnection, I can still see the signal. However, when I try to reconnect it, the following error pops up. And I can never see the BLE signal again. I think the entire code stops running.

// In the debugging mode: 

<info> app: BLE_GAP_EVT_CONNECTED
<error> app: ERROR 13313 [Unknown error code] at D:\StevenW\SDK_Code\example\Steven\20210922 eBTR_BLE_BPM_TV Btn v1\main.c:2075
PC at: 0x0001E849
<error> app: End of error report

This are my codes at line 2075

ret_code_t err_code_ble_nus;
err_code_ble_nus = ble_nus_data_send(&m_nus, nus_string, &bytes_to_send, m_conn_handle);
if ((err_code_ble_nus != NRF_ERROR_INVALID_STATE) && (err_code_ble_nus != NRF_ERROR_NOT_FOUND))
{
APP_ERROR_CHECK(err_code_ble_nus); // Line 2075
}

After Googleing, many people mentioned the same reason & solution (see link 1, link 2, link 3), and their solution is to add the following codes:

case BLE_GATTS_EVT_SYS_ATTR_MISSING:
    err_code = sd_ble_gatts_sys_attr_set(m_conn_handle, NULL, 0);
    APP_ERROR_CHECK(err_code);
    break;

However, this solution doesn't work for me. Any other ideas, please?

Thanks in advance!

StevenW807 · Answer

Thanks for your help, Amanda. 
 I solved the issue by using following code: 
 bytes_to_send = sprintf(nus_string,"%.3f", ble_test_data);

ret_code_t err_code_ble_nus;
err_code_ble_nus = ble_nus_data_send(&m_nus, nus_string, &bytes_to_send, m_conn_handle);

if (err_code_ble_nus == BLE_ERROR_GATTS_SYS_ATTR_MISSING){
 uint32_t err_code = sd_ble_gatts_sys_attr_set(m_conn_handle, NULL, 0, 0);
 APP_ERROR_CHECK(err_code);
 NRF_LOG_INFO("Case 1: Notification Disabled ===================================");
}else if( (err_code_ble_nus != NRF_ERROR_INVALID_STATE) && (err_code_ble_nus != NRF_ERROR_NOT_FOUND) ){ 
 APP_ERROR_CHECK(err_code_ble_nus);
 NRF_LOG_INFO("Case 2");
}else{
 NRF_LOG_INFO("Case 3");
} 
 Initially, when there is no "if statement" for " BLE_ERROR_GATTS_SYS_ATTR_MISSING ", the APP_ERROR_CHCK() in case 2 will stop the entire program. 
 
 I have a follow-up question: When BLE_GATTS_EVT_SYS_ATTR_MISSING , the following code should execute and print " BLE_GATTS_EVT_SYS_ATTR_MISSING ". However, I didn't see the printing " BLE_GATTS_EVT_SYS_ATTR_MISSING " at all. 
 I can see the printing result " BLE_GAP_EVT_CONNECTED ", " BLE_GAP_EVT_DISCONNECTED " and " BLE_DEFAULT " as expected. 
 /**@brief Function for handling BLE events.
 *
 * @param[in] p_ble_evt Bluetooth stack event.
 * @param[in] p_context Unused.
 */
static void ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context)
{
 uint32_t err_code;

 switch (p_ble_evt->header.evt_id)
 {
 case BLE_GAP_EVT_CONNECTED:
 NRF_LOG_INFO("BLE_GAP_EVT_CONNECTED");
 // err_code = bsp_indication_set(BSP_INDICATE_CONNECTED);
 // APP_ERROR_CHECK(err_code);
 m_conn_handle = p_ble_evt->evt.gap_evt.conn_handle;
 err_code = nrf_ble_qwr_conn_handle_assign(&m_qwr, m_conn_handle);
 APP_ERROR_CHECK(err_code);
 break;

 case BLE_GAP_EVT_DISCONNECTED:
 NRF_LOG_INFO("BLE_GAP_EVT_DISCONNECTED");
 // LED indication will be changed when advertising starts.
 m_conn_handle = BLE_CONN_HANDLE_INVALID;
 break;

 case BLE_GAP_EVT_PHY_UPDATE_REQUEST:
 {
 NRF_LOG_INFO("BLE_GAP_EVT_PHY_UPDATE_REQUEST");
 ble_gap_phys_t const phys =
 {
 .rx_phys = BLE_GAP_PHY_AUTO,
 .tx_phys = BLE_GAP_PHY_AUTO,
 };
 err_code = sd_ble_gap_phy_update(p_ble_evt->evt.gap_evt.conn_handle, &phys);
 APP_ERROR_CHECK(err_code);
 } break;

 case BLE_GAP_EVT_SEC_PARAMS_REQUEST:
 NRF_LOG_INFO("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;

 case BLE_GATTS_EVT_SYS_ATTR_MISSING:
 NRF_LOG_INFO("BLE_GATTS_EVT_SYS_ATTR_MISSING");
 // No system attributes have been stored.
 err_code = sd_ble_gatts_sys_attr_set(m_conn_handle, NULL, 0, 0);
 APP_ERROR_CHECK(err_code);
 break;

 case BLE_GATTC_EVT_TIMEOUT:
 NRF_LOG_INFO("BLE_GATTC_EVT_TIMEOUT");
 // Disconnect on GATT Client timeout event.
 err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gattc_evt.conn_handle,
 BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
 APP_ERROR_CHECK(err_code);
 break;

 case BLE_GATTS_EVT_TIMEOUT:
 NRF_LOG_INFO("BLE_GATTS_EVT_TIMEOUT");
 // Disconnect on GATT Server timeout event.
 err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gatts_evt.conn_handle,
 BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
 APP_ERROR_CHECK(err_code);
 break;

 default:
 NRF_LOG_INFO("BLE_DEFAULT");
 // No implementation needed.
 break;
 }
} 
 
 Thanks in advance!