BLE固件开发--如何获取当前连接状态

    在一个 BLE开发项目中，我采用的是TI的CC2541蓝牙BLE SoC，为了防止主从设备连接断开时数据丢失，硬件上加了一个EEPROM，当蓝牙建立连接时，通过Notify发给主机，但当蓝牙连接断开时，采集的数据要存储到EEPROM中（I2C），要实现这一点，需要实时获取蓝牙的连接状态。

    在TI的BLE协议栈中，periperal.h中有如下定义：   

/** * GAP Peripheral Role States. */typedef enum{  GAPROLE_INIT = 0,                       //!< Waiting to be started  GAPROLE_STARTED,                        //!< Started but not advertising  GAPROLE_ADVERTISING,                    //!< Currently Advertising  GAPROLE_WAITING,                        //!< Device is started but not advertising, is in waiting period before advertising again  GAPROLE_WAITING_AFTER_TIMEOUT,          //!< Device just timed out from a connection but is not yet advertising, is in waiting period before advertising again  GAPROLE_CONNECTED,                      //!< In a connection  GAPROLE_CONNECTED_ADV,                  //!< In a connection + advertising  GAPROLE_ERROR                           //!< Error occurred - invalid state} gaprole_States_t;

    以上枚举了从设备的几种状态，那么如何实时的获取gaprole_States_t的当前状态呢？该文件中后面由给出了一个定义：   

/** * Callback structure - must be setup by the application and used when gapRoles_StartDevice() is called. */typedef struct{  gapRolesStateNotify_t    pfnStateChange;  //!< Whenever the device changes state  gapRolesRssiRead_t       pfnRssiRead;     //!< When a valid RSSI is read from controller} gapRolesCBs_t;

    这个结构体上面的注释写的很清楚，必须在application层进行设置并在gapRoles_StartDevice()调用后使用。这里pfnStateChange成员变量是一个回调函数指针，用来处理相应状态变化下的操作。所以抓住这一点，也就实时获取到了从设备的连接状态变化。那么接下来我们只要在Application层定义一个pfnStateChange的回调函数并用来初始化一个gapRolesCBs_t的结构体即可。

    回调函数定义如下：（gLinkStatus是自定义的一个变量，用来表示连接状态）   

static void peripheralStateNotificationCB( gaprole_States_t newState ){    switch ( newState )  {    case GAPROLE_STARTED:      {        uint8 ownAddress[B_ADDR_LEN];        uint8 systemId[DEVINFO_SYSTEM_ID_LEN];               GAPRole_GetParameter(GAPROLE_BD_ADDR, ownAddress);        // use 6 bytes of device address for 8 bytes of system ID value        systemId[0] = ownAddress[0];        systemId[1] = ownAddress[1];        systemId[2] = ownAddress[2];        systemId[3] = ownAddress[3];        systemId[4] = ownAddress[4];        systemId[5] = ownAddress[5];        DevInfo_SetParameter(DEVINFO_SYSTEM_ID, DEVINFO_SYSTEM_ID_LEN, systemId);        gLinkStatus=0;      }      break;    case GAPROLE_ADVERTISING:      gLinkStatus=0;      break;    case GAPROLE_CONNECTED:      gLinkStatus=1;      break;    case GAPROLE_CONNECTED_ADV:      gLinkStatus=0;      break;                case GAPROLE_WAITING:      gLinkStatus=0;      break;    case GAPROLE_WAITING_AFTER_TIMEOUT:      gLinkStatus=0;      break;    case GAPROLE_ERROR:      gLinkStatus=0;      break;    default:      break;  }}

    然后用该回调函数初始化一个gapRolesCBs_t的结构体： 

// GAP Role Callbacksstatic gapRolesCBs_t TemperatureSensor_PeripheralCBs ={  peripheralStateNotificationCB,  // Profile State Change Callbacks  NULL                            // When a valid RSSI is read from controller (not used by application)};

    这样，在gapRoles_StartDevice()调用后（在应用层的任务处理函数中调用），便可以通过自定义的gLinkStatus变量来实时获取当前的连接状态了。