主机读取20字节错误，读取19字节正确

#define SIMPLEPROFILE_CHAR5_LEN           20   

// Characteristic 5 Value
static uint8 simpleProfileChar5[SIMPLEPROFILE_CHAR5_LEN] = { 0, 0, 0, 0, 0 };


    // Characteristic 5 Declaration
    {
      { ATT_BT_UUID_SIZE, characterUUID },
      GATT_PERMIT_READ,
      0,
      &simpleProfileChar5Props
    },

      // Characteristic Value 5
      {
        { ATT_BT_UUID_SIZE, simpleProfilechar5UUID },
        GATT_PERMIT_READ | GATT_PERMIT_WRITE,
        0,
        simpleProfileChar5
      },

      // Characteristic 5 User Description
      {
        { ATT_BT_UUID_SIZE, charUserDescUUID },
        GATT_PERMIT_READ,
        0,
        simpleProfileChar5UserDesp
      },

static uint8 simpleProfile_ReadAttrCB( uint16 connHandle, gattAttribute_t *pAttr,
                            uint8 *pValue, uint8 *pLen, uint16 offset, uint8 maxLen )
{
  bStatus_t status = SUCCESS;
  // If attribute permissions require authorization to read, return error
  if ( gattPermitAuthorRead( pAttr->permissions ) )
  {
    // Insufficient authorization
    return ( ATT_ERR_INSUFFICIENT_AUTHOR );
  }
  
  // Make sure it's not a blob operation (no attributes in the profile are long)
  if ( offset > 0 )
  {
    return ( ATT_ERR_ATTR_NOT_LONG );
  }

  if ( pAttr->type.len == ATT_BT_UUID_SIZE )
  {
    // 16-bit UUID
    uint16 uuid = BUILD_UINT16( pAttr->type.uuid[0], pAttr->type.uuid[1]);
    switch ( uuid )
    {
      // No need for "GATT_SERVICE_UUID" or "GATT_CLIENT_CHAR_CFG_UUID" cases;
      // gattserverapp handles those reads
      // characteristics 1 and 2 have read permissions
      // characteritisc 3 does not have read permissions; therefore it is not
      //   included here
      // characteristic 4 does not have read permissions, but because it
      //   can be sent as a notification, it is included here
      case SIMPLEPROFILE_CHAR1_UUID:
      case SIMPLEPROFILE_CHAR2_UUID:
      case SIMPLEPROFILE_CHAR3_UUID:
      case SIMPLEPROFILE_CHAR4_UUID:
        *pLen = 1;
        pValue[0] = *pAttr->pValue;
        break;
      case SIMPLEPROFILE_CHAR5_UUID:
        *pLen = 20;
        VOID osal_memcpy( pValue, pAttr->pValue, /*SIMPLEPROFILE_CHAR5_LEN*/ 20);//读数据时只能读到20个以下byte
        break;
        #if 1
      case SIMPLEPROFILE_CHAR6_UUID:
       *pLen = 20;
        VOID osal_memcpy( pValue, pAttr->pValue, /*SIMPLEPROFILE_CHAR5_LEN*/20 );//读数据时只能读到20个以下byte
        break;
        #endif
      default:
        // Should never get here! (characteristics 3 and 4 do not have read permissions)
        *pLen = 0;
        status = ATT_ERR_ATTR_NOT_FOUND;
        break;
    }
  }
  else
  {
    // 128-bit UUID
    *pLen = 0;
    status = ATT_ERR_INVALID_HANDLE;
  }
  return ( status );
}

会出现以下问题
ATTR_NOT_FOUND

参考这段代码：

if ( ( pMsg->method == ATT_FIND_BY_TYPE_VALUE_RSP &&
pMsg->hdr.status == bleProcedureComplete ) ||
( pMsg->method == ATT_ERROR_RSP ) )
{
if ( simpleBLESvcStartHdl != 0 )
{
// Discover characteristic
simpleBLEDiscState = BLE_DISC_STATE_AUTH;

req.startHandle = simpleBLESvcStartHdl;
req.endHandle = 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_ReadUsingCharUUID( simpleBLEConnHandle, &req, simpleBLETaskId );
GATT_DiscCharsByUUID( simpleBLEConnHandle, &req, simpleBLETaskId );
}
}