编译 W801 的固件代码 (没记错是 wm_sdk_w80x_20211115. zip) , 然后烧录固件到 W801.
在串口调试助手输入:  
t-bt-on
t-ble-adv (1) 
蓝牙启动成功,  并正常发送广播报文
手机打开蓝牙并扫描到 W801. 点击配对成功.
然后, 手机端将配对好的 W801 设备删除, 板子也重新上电 (排除干扰) .
串口助手丽依次输入 t-bt-on,  t-ble-adv (1) ,  手机端还是能扫描到 W801 设备.  但是
点击配对时却失败,  串口终端内容是这样的:  
[WM_I]  0: 00: 01. 288  adapter status = bt_state_on
[WM_I]  0: 00: 01. 294  init base application
[WM_I]  0: 00: 06. 968  ### tls_ble_demo_adv type=1
[WM_I]  0: 00: 06. 974  Starting advertising
GAP procedure initiated:  advertise;  disc_mode=2 direct_addr_type=0 direct_addr=00: 00: 00: 00: 00: 00 adv_channel_map=0 own_addr_type=0 adv_filter_policy=0 adv_itvl_min=64 adv_itvl_max=64
[WM_I]  0: 00: 11. 806  gap_event,  [BLE_GAP_EVENT_CONNECT]
[WM_I]  0: 00: 12. 068  gap_event,  [BLE_GAP_EVENT_REPEAT_PAIRING]
[WM_I]  0: 00: 45. 070  gap_event,  [BLE_GAP_EVENT_DISCONNECT]是不是这个 BLE_GAP_EVENT_REPEAT_PAIRING 没处理好? 源码没有改动, 只是编译后烧录到板子上.
OK,  我们做个记录
https: //github. com/h2zero/NimBLE-Arduino/issues/116
case BLE_GAP_EVENT_REPEAT_PAIRING: 
    /* We already have a bond with the peer,  but it is attempting to
     * establish a new secure link.   This app sacrifices security for
     * convenience:  just throw away the old bond and accept the new link. 
     */
    /* Delete the old bond.  */
    rc = ble_gap_conn_find (event- repeat_pairing. conn_handle,  &desc) ; 
    assert (rc == 0) ; 
    ble_store_util_delete_peer (&desc. peer_id_addr) ; 
    
    TLS_BT_APPL_TRACE_DEBUG ("! ! ! BLE_GAP_EVENT_REPEAT_PAIRING\r\n") ; 
    return BLE_GAP_REPEAT_PAIRING_RETRY; 搜索后发现, 原来是要删除原来的配对信息 (持久化存储) . 然后再 wm_ble_server_api_demo. c 里是有个 case 处理的. 但是 wm_ble_gap. c 里没有. 所以发送广播时就酱紫.