一、情况

最近使用CC2541做主机来连接CH573做测试，发现获取不到CH573的notify属性的特征值，后面发现，通过 GATT_ReadUsingCharUUID() 是搜索不到的，而通过 GATT_DiscCharsByUUID() 是可以搜索到的。

二、需要注意的点

1. GATT_ReadUsingCharUUID() 和 GATT_DiscCharsByUUID()的区别：
   由于一个characteristic定义是由：characteristic declaration，characteristic value，characteristic configuration组成；GATT_ReadUsingCharUUID()读取到的是 characteristic value的hdl，而 GATT_DiscCharsByUUID() 读取到的 是 characteristic declaration 的hdl。

2. 对于 characteristic configuration ，只能通过 GATT_ReadUsingCharUUID() 来操作，所以我们这里可以这样做： 对于特征值的 value的hdl ，我们可以通过 disc找到hdl +1 处理，对于需要ccc打开notify选项，则通过read来直接读取即可。

三、代码

1. 主机

/*********************************************************************
 * @fn      simpleBLEGATTDiscoveryEvent
 *
 * @brief   Process GATT discovery event
 *
 * @return  none
 */
static void simpleBLEGATTDiscoveryEvent( gattMsgEvent_t *pMsg )
{
    
  attReadByTypeReq_t req;
  BLE_DEV *p =  simpleBLECentralGetDev(pMsg->connHandle);
  
   if ( p->simpleBLEDiscState == BLE_DISC_STATE_SVC )   
   {
        
      // Service found, store handles    
      if ( pMsg->method == ATT_FIND_BY_TYPE_VALUE_RSP &&       
       pMsg->msg.findByTypeValueRsp.numInfo > 0 )   
      {
          
        p->simpleBLESvcStartHdl = pMsg->msg.findByTypeValueRsp.handlesInfo[0].handle;  
        p->simpleBLESvcEndHdl = pMsg->msg.findByTypeValueRsp.handlesInfo[0].grpEndHandle;    
      }    
  
      // If procedure complete    
      if ( ( pMsg->method == ATT_FIND_BY_TYPE_VALUE_RSP  &&           
      pMsg->hdr.status == bleProcedureComplete ) ||         
      ( pMsg->method == ATT_ERROR_RSP ) )   
      {
          
        if ( p->simpleBLESvcStartHdl != 0 )      
        {
            
          // Discover characteristic       
          p->simpleBLEDiscState = BLE_DISC_STATE_CHAR1;      
          req.startHandle = p->simpleBLESvcStartHdl;    
          req.endHandle = p->simpleBLESvcEndHdl;    
          req.type.len = ATT_BT_UUID_SIZE;
          req.type.uuid[0] = LO_UINT16(SIMPLEPROFILE_CHAR1_UUID);    
          req.type.uuid[1] = HI_UINT16(SIMPLEPROFILE_CHAR1_UUID);      
          GATT_DiscCharsByUUID( p->simpleBLEConnHandle, &req, simpleBLETaskId );     
        }    
      }  
  }  
  else if ( p->simpleBLEDiscState == BLE_DISC_STATE_CHAR1 )  //先找CHAR1
  {
        
    NPI_PrintValue("1 pMsg->method", pMsg->method, 10);
    NPI_PrintValue("1 numPairs", pMsg->msg.readByTypeRsp.numPairs, 10);
    // Characteristic found, store handle    
     if ( pMsg->method == ATT_READ_BY_TYPE_RSP &&      
        pMsg->msg.readByTypeRsp.numPairs > 0 )
        {
          
           p->simpleBLECharHdl[0] = BUILD_UINT16( pMsg->msg.readByTypeRsp.dataList[0],                         
           pMsg->msg.readByTypeRsp.dataList[1] );      
           
           NPI_PrintValue("1 hdl", p->simpleBLECharHdl[0], 10);
    
           LCD_WRITE_STRING( "CHAR 1 Found", HAL_LCD_LINE_3 );      
           p->simpleBLEProcedureInProgress = TRUE;      
       }
     else // pMsg->msg.readByTypeRsp.numPairs is 0.
     {
    
       p->simpleBLEDiscState = BLE_DISC_STATE_CHAR6;    
       req.startHandle = p->simpleBLESvcStartHdl;  
       req.endHandle = p->simpleBLESvcEndHdl;   
       req.type.len = ATT_BT_UUID_SIZE;    
       req.type.uuid[0] = LO_UINT16(SIMPLEPROFILE_CHAR6_UUID);   
       req.type.uuid[1] = HI_UINT16(SIMPLEPROFILE_CHAR6_UUID);    
       GATT_DiscCharsByUUID( p->simpleBLEConnHandle, &req, simpleBLETaskId );  
     }
  }        
  else if (p->simpleBLEDiscState == BLE_DISC_STATE_CHAR6)  //再找CHAR6
  {
         // Characteristic found, store handle    
    
    NPI_PrintValue("6 pMsg->method", pMsg->method, 10);
    NPI_PrintValue("6 numPairs", pMsg->msg.readByTypeRsp.numPairs, 10);
    
    if ( (pMsg->method == ATT_READ_BY_TYPE_RSP)  &&     
    pMsg->msg.readByTypeRsp.numPairs > 0 )    
    {
          
      p->simpleBLECharHdl[5] = BUILD_UINT16( pMsg->msg.readByTypeRsp.dataList[0],                                      
      pMsg->msg.readByTypeRsp.dataList[1] );     
      LCD_WRITE_STRING( "CHAR 6 Found", HAL_LCD_LINE_4 );
     // p->simpleBLEProcedureInProgress = FALSE;  
      p->simpleBLEProcedureInProgress = TRUE;   
      
      NPI_PrintValue("6 hdl", p->simpleBLECharHdl[5], 10);
    }
    else
    {
    
      p->simpleBLEDiscState = BLE_DISC_STATE_CCC;
      
       req.startHandle = p->simpleBLESvcStartHdl;  
       req.endHandle = p->simpleBLESvcEndHdl;   
       req.type.len = ATT_BT_UUID_SIZE;    
       req.type.uuid[0] = LO_UINT16(0x2902);   
       req.type.uuid[1] = HI_UINT16(0x2902);    
       GATT_ReadUsingCharUUID( p->simpleBLEConnHandle, &req, simpleBLETaskId ); 
    }
    //p->simpleBLEDiscState = BLE_DISC_STATE_IDLE;
  }
  else if (p->simpleBLEDiscState == BLE_DISC_STATE_CCC) //再找CCC
  {
    
    NPI_PrintValue("ccc pMsg->method", pMsg->method, 10);
    NPI_PrintValue("ccc numPairs", pMsg->msg.readByTypeRsp.numPairs, 10);
    if ( (pMsg->method == ATT_READ_BY_TYPE_RSP)  &&     
    pMsg->msg.readByTypeRsp.numPairs > 0 )  
    {
    
      
      ccc_dhl = BUILD_UINT16( pMsg->msg.readByTypeRsp.dataList[0],                                      
      pMsg->msg.readByTypeRsp.dataList[1] ); 
      NPI_PrintValue("ccc hdl", ccc_dhl, 10);
      
      
    }
    else													//CHAR6完全找到后 写CCC了直接
    {
    
       p->simpleBLEDiscState = BLE_DISC_STATE_IDLE;
       p->simpleBLEProcedureInProgress = FALSE;
       
      // Do a write
      attWriteReq_t req;
      
      req.handle = ccc_dhl;
      req.len = 2;
      req.sig = 0;
      req.cmd = 0;
      
      req.value[0] = 1; //写 1 打开notify选项
      req.value[1] = 0;
      
      uint8 status;
      status = GATT_WriteCharValue( p->simpleBLEConnHandle, &req, simpleBLETaskId ); // 发送数据
      if(SUCCESS != status)
      {
    
          NPI_PrintValue("Write Error :", status, 10);
      }
      else
      {
    
        NPI_PrintValue("ccc Write success :", status, 10);
      }
       
       
    }
   
  }
}

1. LOG

  [KEY UP pressed!]
Discovering...



>>>GAP_DEVICE_INFO_EVENT
>>>GAP_DEVICE_INFO_EVENT
>>>GAP_DEVICE_INFO_EVENT
Key DOWN = Read RSSI
>>>GAP_DEVICE_DISCOVERY_EVENT
Devices Found 1[0]=0x84C2E43F4F47
Key CENTER = Connect
Connecting......
Idx= 0
Connecting
0x84C2E43F4F47
Idx= 0
>>>GAP_LINK_ESTABLISHED_EVENT
0x84C2E43F4F47
Key DOWN = Read RSSI
1 pMsg->method 9
1 numPairs 1
1 hdl 34
CHAR 1 Found
1 pMsg->method 96 pMsg->method 9
6 numPairs 1
CHAR 6 Found
6 hdl 43
6 pMsg->method 9
6 numPairs 0
ccc pMsg->method 9
ccc numPairs 1
ccc hdl 45ccc pMsg->method 9
ccc numPairs 0
ccc Write success : 0
Write sent: 0
ATT_HANDLE_VALUE_NOTI
ATT_HANDLE_VALUE_NOTI