关于低功耗蓝牙的连接参数更新
Posted xiaoshideyuxiang
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首先要明确:连接参数是由主机端确定的,从机端可以发起更新连接参数的请求。主机端可以直接下发连接参数,而从机端则只能是发起更新请求并附带想要的连接参数范围。
在初始化中将想要的连接参数设置进osal( 在和ios设备连接时需要注意一些规则,在前面有提到 ):
GAPRole_SetParameter( GAPROLE_PARAM_UPDATE_ENABLE, sizeof( uint8 ), &enable_update_request );
GAPRole_SetParameter( GAPROLE_MIN_CONN_INTERVAL, sizeof( uint16 ), &desired_min_interval );
GAPRole_SetParameter( GAPROLE_MAX_CONN_INTERVAL, sizeof( uint16 ), &desired_max_interval );
GAPRole_SetParameter( GAPROLE_SLAVE_LATENCY, sizeof( uint16 ), &desired_slave_latency );
GAPRole_SetParameter( GAPROLE_TIMEOUT_MULTIPLIER, sizeof( uint16 ), &desired_conn_timeout );
追踪下GAPRole_SetParameter函数中这些参数的运作:
case GAPROLE_MIN_CONN_INTERVAL:
uint16 newInterval = *((uint16*)pValue);
if ( len == sizeof ( uint16 ) &&
( newInterval >= MIN_CONN_INTERVAL ) &&
( newInterval <= MAX_CONN_INTERVAL ) )
gapRole_MinConnInterval = newInterval;
else
ret = bleInvalidRange;
break;
都是存储在全局变量中,那么这些参数是何时发出去的呢?
且看:
在建立连接后会产生一个MSG然后在gapRole_ProcessGAPMsg函数中的GAP_LINK_PARAM_UPDATE_EVENT事件
gap.h中有对这一事件的介绍
case GAP_LINK_ESTABLISHED_EVENT:
gapEstLinkReqEvent_t *pPkt = (gapEstLinkReqEvent_t *)pMsg;
if ( pPkt->hdr.status == SUCCESS )
VOID osal_memcpy( gapRole_ConnectedDevAddr, pPkt->devAddr, B_ADDR_LEN );
gapRole_ConnectionHandle = pPkt->connectionHandle;
gapRole_state = GAPROLE_CONNECTED;
if ( gapRole_RSSIReadRate )
// Start the RSSI Reads
VOID osal_start_timerEx( gapRole_TaskID, RSSI_READ_EVT, gapRole_RSSIReadRate );
// Store connection information
gapRole_ConnInterval = pPkt->connInterval;
gapRole_ConnSlaveLatency = pPkt->connLatency;
gapRole_ConnTimeout = pPkt->connTimeout;
// Check whether update parameter request is enabled
if ( gapRole_ParamUpdateEnable == TRUE )
// Get the minimum time upon connection establishment before the
// peripheral can start a connection update procedure.
uint16 timeout = GAP_GetParamValue( TGAP_CONN_PAUSE_PERIPHERAL );
osal_start_timerEx( gapRole_TaskID, START_CONN_UPDATE_EVT, timeout*1000 );
// Notify the Bond Manager to the connection
VOID GAPBondMgr_LinkEst( pPkt->devAddrType, pPkt->devAddr, pPkt->connectionHandle, GAP_PROFILE_PERIPHERAL );
// Set enabler to FALSE; device will become discoverable again when
// this value gets set to TRUE
gapRole_AdvEnabled = FALSE;
else if ( pPkt->hdr.status == bleGAPConnNotAcceptable )
// Set enabler to FALSE; device will become discoverable again when
// this value gets set to TRUE
gapRole_AdvEnabled = FALSE;
// Go to WAITING state, and then start advertising
gapRole_state = GAPROLE_WAITING;
else
gapRole_state = GAPROLE_ERROR;
notify = TRUE;
break;
osal_start_timerEx( gapRole_TaskID, START_CONN_UPDATE_EVT, timeout*1000 );
这个事件便是发起连接参数更新,这个timeout是为了让连接更稳定,在建立连接之后得经过一段稳定的时间在更新参数
有网友的做法是在peripheralStateNotificationCB函数中的GAPROLE_CONNECTED里面添加更新参数的函数手动发起更新请求,不知这种做法是否有风险。
GAPRole_SendUpdateParam( uint16 minConnInterval, uint16 maxConnInterval,
uint16 latency, uint16 connTimeout, uint8 handleFailure );
也可以用下面这个中方式,两者本质都是用gapRole_startConnUpdate( GAPROLE_NO_ACTION );
GAPRole_SetParameter( GAPROLE_PARAM_UPDATE_REQ, sizeof ( uint8 ), TRUE );
怎么获取实时连接参数?
好办!
如下函数,注册一个回调函数,然后就可以得到connInterval,connSlaveLatency,connTimeout这三项参数,当参数更新成功是进入回调;因此可以在回调函数里面用LCD,打印,发给APP等等各种方式来展示
GAPRole_RegisterAppCBs( gapRolesParamUpdateCB_t *pParamUpdateCB );
顺便贴一下回调函数的调用:
case GAP_LINK_PARAM_UPDATE_EVENT:
gapLinkUpdateEvent_t *pPkt = (gapLinkUpdateEvent_t *)pMsg;
// Cancel connection param update timeout timer (if active)
VOID osal_stop_timerEx( gapRole_TaskID, CONN_PARAM_TIMEOUT_EVT );
if ( pPkt->hdr.status == SUCCESS )
// Store new connection parameters
gapRole_ConnInterval = pPkt->connInterval;
gapRole_ConnSlaveLatency = pPkt->connLatency;
gapRole_ConnTimeout = pPkt->connTimeout;
// Make sure there's no pending connection update procedure
if ( osal_get_timeoutEx( gapRole_TaskID, START_CONN_UPDATE_EVT ) == 0 )
// Notify the application with the new connection parameters
if ( pGapRoles_ParamUpdateCB != NULL )
(*pGapRoles_ParamUpdateCB)( gapRole_ConnInterval,
gapRole_ConnSlaveLatency,
gapRole_ConnTimeout );
break;
就写到这了,其他验证过会再更新
第一次写,有点乱。。。
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