CCS/CC2640R2F: Android phone connected fail with CC2640 sometimes

Tool/software: Code Composer Studio

Running the simple_peripheral project in CC2640 LAUNCHPAD . When my android phone connecting with CC2640 , it will fail sometimes ,and CC2640 enters in "GAPROLE_WAITING" .Then CC2640 stops advertising . The probability of the above situation is about thirty percent . The probability is lower when using HUAWEI phone ,and is higher when using Xiaomi .

How to configure CC2640 to ensure the connecting success ?

1、my configuration of CC2640
(1)configure pair mode in SimpleBLEPeripheral_init(void)

// Setup the GAP Bond Manager. For more information see the section in the
// User's Guide:
// <a href="software-dl.ti.com/.../a>
{
  // Don't send a pairing request after connecting; the peer device must
  // initiate pairing
  //uint8_t pairMode = GAPBOND_PAIRING_MODE_WAIT_FOR_REQ;
    uint8_t pairMode = GAPBOND_PAIRING_MODE_INITIATE;
  // Use authenticated pairing: require passcode.
  uint8_t mitm = TRUE;
  // This device only has display capabilities. Therefore, it will display the
  // passcode during pairing. However, since the default passcode is being
  // used, there is no need to display anything.
  uint8_t ioCap = GAPBOND_IO_CAP_DISPLAY_ONLY;   //手机不显示密码，只有这个可用


  // Request bonding (storing long-term keys for re-encryption upon subsequent
  // connections without repairing)
  uint8_t bonding = TRUE; 


  GAPBondMgr_SetParameter(GAPBOND_PAIRING_MODE, sizeof(uint8_t), &pairMode);
  GAPBondMgr_SetParameter(GAPBOND_MITM_PROTECTION, sizeof(uint8_t), &mitm);
  GAPBondMgr_SetParameter(GAPBOND_IO_CAPABILITIES, sizeof(uint8_t), &ioCap);
  GAPBondMgr_SetParameter(GAPBOND_BONDING_ENABLED, sizeof(uint8_t), &bonding);
  
}

(2)log print of “GAP_LINK_ESTABLISHED_EVENT” through UART

static void gapRole_processGAPMsg(gapEventHdr_t *pMsg)
{
......
        case GAP_LINK_ESTABLISHED_EVENT:
      {
          //fuheng
          UART_write(uart, "GAP_LINK_ESTABLISHED_EVENT\r\n", sizeof("GAP_LINK_ESTABLISHED_EVENT\r\n"));
       ......
      }
......
}

(3)log print of “GAPROLE_WAITING” through UART

static void SimpleBLEPeripheral_processStateChangeEvt(gaprole_States_t newState)
{
   .......
    case GAPROLE_WAITING:
      Util_stopClock(&periodicClock);
      SimpleBLEPeripheral_freeAttRsp(bleNotConnected);

      Display_print0(dispHandle, 2, 0, "Disconnected");
      UART_write(uart, "GAPROLE_WAITING\r\n", sizeof("GAPROLE_WAITING\r\n"));
   ......
}

2、my steps of connecting
(1)Running the simple_peripheral project in CC2640 LAUNCHPAD .Serial port assistant shows CC2640 is advertising , as shown in picture 1 .

picture 1

(2)Scaning CC2640 in BLE SCANNER on android phone , as shown in picture 2.

picture 2

(3)press the "CONNECT " button . However , serial port assistant shows connecting fail , as shown in picture 1.

(4)CC2640 enters in "GAPROLE_WAITING" .Then CC2640 stops advertising , as shown in picture 1.

3、analysis of packet sniffer
(1)using packet sniffer , several packets about “Scan request / response” has been captured , as shown in picture 3 .

picture 3

(2)several packets about "FCS = ERROR" has been captured , as shown in picture 4 . No packets about “Connection establishment” has been captured .

picture 4

(3)according to the "BLE sniffer guide ", packets about “Connection establishment” can be captured , as shown in picture 5.

picture 5

(4)the packet sniffer when conneting failed can be downloade from attachments, which is named in " 02_fail_pairing.psd ".

(5)the packet sniffer when conneting successed can be downloade from attachments, which is named in "14hornorV8-sucess.psd ".

4、attachments

（1）path of simple_peripheral project on my computer:
C:\ti\simplelink_cc2640r2_sdk_1_40_00_45\examples\rtos\CC2640R2_LAUNCHXL\blestack\simple_peripheral

（2）The packet sniffer named in " 02_fail_pairing.psd " can be downloaded here:

02_fail_pairing.psd

（3）The packet sniffer named in "14hornorV8-sucess.psd " can be downloaded here:

14hornorV8-sucess.psd

（4）《core_V5.0.pdf》can be downloaded here:
www.bluetooth.com/.../bluetooth-core-specification

（5）simplelink_cc2640r2_sdk_1_40_00_45 can be downloaded here:：
dev.ti.com/.../

（6）CC2640R2 launchpad can be bought here:
www.ti.com/.../launchxl-cc2640r2

(7)"BLE sniffer guide " can be downloaded here:：
processors.wiki.ti.com/.../BLE_sniffer_guide

(8)soure code of my workspace can be downloaded here:

CCSworkspace240.rar

5、my developing environment
CCS:Code Composer Studio 7.2.0
SDK:simplelink_cc2640r2_sdk_1_40_00_45
hardware:CC26640R2 launchpad develop kit
VS: Microsoft Visual C++ 2010 Express
OS：win7 64 bit
Serial assistant: sscom5.13.1.exe
android phone:hornor V8 (android 7.0)