TI BLE:SCAN

主机会运行SCAN来搜寻广播中的设备

运行函数：

GAPCentralRole_StartDiscovery( DEFAULT_DISCOVERY_MODE,
DEFAULT_DISCOVERY_ACTIVE_SCAN,
DEFAULT_DISCOVERY_WHITE_LIST );

/**
 * @brief   Start a device discovery scan.
 *
 * Public function defined in central.h.
 */
bStatus_t GAPCentralRole_StartDiscovery( uint8 mode, uint8 activeScan, uint8 whiteList )
{
  gapDevDiscReq_t params;

  params.taskID = gapCentralRoleTaskId;
  params.mode = mode;
  params.activeScan = activeScan;
  params.whiteList = whiteList;

  return GAP_DeviceDiscoveryRequest( &params );
}

最终使用的是API：GAP_DeviceDiscoveryRequest

来看几个参数：DEFAULT_DISCOVERY_MODE

// Discovey mode (limited, general, all)
#define DEFAULT_DISCOVERY_MODE     DEVDISC_MODE_ALL

#define DEVDISC_MODE_NONDISCOVERABLE 0x00 //!< No discoverable setting
#define DEVDISC_MODE_GENERAL 0x01 //!< General Discoverable devices
#define DEVDISC_MODE_LIMITED 0x02 //!< Limited Discoverable devices
#define DEVDISC_MODE_ALL 0x03 //!< Not filtered

// TRUE to use active scan
#define DEFAULT_DISCOVERY_ACTIVE_SCAN TRUE

// TRUE to use white list during discovery
#define DEFAULT_DISCOVERY_WHITE_LIST FALSE

//TRUE to only allow advertisements from devices in the white list. 

初始化函数中有些设置：

// Setup Central Profile
{
uint8 scanRes = DEFAULT_MAX_SCAN_RES;
GAPCentralRole_SetParameter ( GAPCENTRALROLE_MAX_SCAN_RES, sizeof( uint8 ), &scanRes );
}

// Maximum number of scan responses
#define DEFAULT_MAX_SCAN_RES 8

最大的支持扫描到的器件数，为8

GAP_SetParamValue( TGAP_GEN_DISC_SCAN, DEFAULT_SCAN_DURATION );
GAP_SetParamValue( TGAP_LIM_DISC_SCAN, DEFAULT_SCAN_DURATION );

// Scan duration in ms
#define DEFAULT_SCAN_DURATION 4000

#define TGAP_GEN_DISC_SCAN 2 //!< Minimum time to perform scanning, when performing General Discovery proc (mSec)
#define TGAP_LIM_DISC_SCAN 3 //!< Minimum time to perform scanning, when performing Limited Discovery proc (mSec)

主机的发现过程，有两个事件：GAP_DEVICE_INFO_EVENT，GAP_DEVICE_DISCOVERY_EVENT

#define GAP_DEVICE_INFO_EVENT                 0x0D //!< Sent during the Device Discovery Process when a device is discovered. This event is sent as an OSAL message defined as gapDeviceInfoEvent_t.

发现当中每发现一个device就触发一次

#define GAP_DEVICE_DISCOVERY_EVENT            0x01 //!< Sent when the Device Discovery Process is complete. This event is sent as an OSAL message defined as gapDevDiscEvent_t.

发现结束时候调用

case GAP_DEVICE_INFO_EVENT:
      {
        // if filtering device discovery results based on service UUID
        if ( DEFAULT_DEV_DISC_BY_SVC_UUID == TRUE )
        {
          if ( simpleBLEFindSvcUuid( SIMPLEPROFILE_SERV_UUID,
                                     pEvent->deviceInfo.pEvtData,
                                     pEvent->deviceInfo.dataLen ) )
          {
            simpleBLEAddDeviceInfo( pEvent->deviceInfo.addr, pEvent->deviceInfo.addrType );
          }
        }
      }
      break;

每次发现会调用两个函数：simpleBLEFindSvcUuid，确定发现的设备SvcUUid是否匹配，匹配的话调用simpleBLEAddDeviceInfo将其地址加入列表

/*********************************************************************
 * @fn      simpleBLEFindSvcUuid
 *
 * @brief   Find a given UUID in an advertiser's service UUID list.
 *
 * @return  TRUE if service UUID found
 */
static bool simpleBLEFindSvcUuid( uint16 uuid, uint8 *pData, uint8 dataLen )
{
  uint8 adLen;
  uint8 adType;
  uint8 *pEnd;
  
  pEnd = pData + dataLen - 1;
  
  // While end of data not reached
  while ( pData < pEnd )
  {
    // Get length of next AD item
    adLen = *pData++;
    if ( adLen > 0 )
    {
      adType = *pData;
      
      // If AD type is for 16-bit service UUID
      if ( adType == GAP_ADTYPE_16BIT_MORE || adType == GAP_ADTYPE_16BIT_COMPLETE )
      {
        pData++;
        adLen--;
        
        // For each UUID in list
        while ( adLen >= 2 && pData < pEnd )
        {
          // Check for match
          if ( pData[0] == LO_UINT16(uuid) && pData[1] == HI_UINT16(uuid) )
          {
            // Match found
            return TRUE;
          }
          
          // Go to next
          pData += 2;
          adLen -= 2;
        }
        
        // Handle possible erroneous extra byte in UUID list
        if ( adLen == 1 )
        {
          pData++;
        }
      }
      else
      {
        // Go to next item
        pData += adLen;
      }
    }
  }
  
  // Match not found
  return FALSE;
}

这个函数利用广播数据格式来判断，先找到类型字节，判断类型是否是uuid，是的话判断内容，不是的话调到下一段内容，把广播格式再粘一次

/ GAP - Advertisement data (max size = 31 bytes, though this is
// best kept short to conserve power while advertisting)
static uint8 advertData[] =
{
  // Flags; this sets the device to use limited discoverable
  // mode (advertises for 30 seconds at a time) instead of general
  // discoverable mode (advertises indefinitely)
  0x02,   // length of this data
  GAP_ADTYPE_FLAGS,
  DEFAULT_DISCOVERABLE_MODE | GAP_ADTYPE_FLAGS_BREDR_NOT_SUPPORTED,

  // service UUID, to notify central devices what services are included
  // in this peripheral
  0x03,   // length of this data
  GAP_ADTYPE_16BIT_MORE,      // some of the UUID's, but not all
  LO_UINT16( SIMPLEPROFILE_SERV_UUID ),
  HI_UINT16( SIMPLEPROFILE_SERV_UUID ),

};

如果是的话加入数组当中，也将扫描到的设备数+1

/*********************************************************************
 * @fn      simpleBLEAddDeviceInfo
 *
 * @brief   Add a device to the device discovery result list
 *
 * @return  none
 */
static void simpleBLEAddDeviceInfo( uint8 *pAddr, uint8 addrType )
{
  uint8 i;
  
  // If result count not at max
  if ( simpleBLEScanRes < DEFAULT_MAX_SCAN_RES )
  {
    // Check if device is already in scan results
    for ( i = 0; i < simpleBLEScanRes; i++ )
    {
      if ( osal_memcmp( pAddr, simpleBLEDevList[i].addr , B_ADDR_LEN ) )
      {
        return;
      }
    }
    
    // Add addr to scan result list
    osal_memcpy( simpleBLEDevList[simpleBLEScanRes].addr, pAddr, B_ADDR_LEN );
    simpleBLEDevList[simpleBLEScanRes].addrType = addrType;
    
    // Increment scan result count
    simpleBLEScanRes++;
  }
}

发现结束后会将数组转移做些存储然后指示用户下一步

case GAP_DEVICE_DISCOVERY_EVENT:
      {
        // discovery complete
        simpleBLEScanning = FALSE;

        // if not filtering device discovery results based on service UUID
        if ( DEFAULT_DEV_DISC_BY_SVC_UUID == FALSE )
        {
          // Copy results
          simpleBLEScanRes = pEvent->discCmpl.numDevs;
          osal_memcpy( simpleBLEDevList, pEvent->discCmpl.pDevList,
                       (sizeof( gapDevRec_t ) * pEvent->discCmpl.numDevs) );
        }
        
        LCD_WRITE_STRING_VALUE( "Devices Found", simpleBLEScanRes,
                                10, HAL_LCD_LINE_1 );
        if ( simpleBLEScanRes > 0 )
        {
          LCD_WRITE_STRING( "<- To Select", HAL_LCD_LINE_2 );
        }

        // initialize scan index to last device
        simpleBLEScanIdx = simpleBLEScanRes;

      }
      break;

key里面有个更新显示，对于收到的device比较多的时候：

 if ( keys & HAL_KEY_LEFT )
  {
    // Display discovery results
    if ( !simpleBLEScanning && simpleBLEScanRes > 0 )
    {
        // Increment index of current result (with wraparound)
        simpleBLEScanIdx++;
        if ( simpleBLEScanIdx >= simpleBLEScanRes )
        {
          simpleBLEScanIdx = 0;
        }
        
        LCD_WRITE_STRING_VALUE( "Device", simpleBLEScanIdx + 1,
                                10, HAL_LCD_LINE_1 );
        LCD_WRITE_STRING( bdAddr2Str( simpleBLEDevList[simpleBLEScanIdx].addr ),
                          HAL_LCD_LINE_2 );
    }
  }