蓝牙4.0协议栈按键流程分析

1、蓝牙4.0协议栈按键流程分析在介绍蓝牙按键流程分析之前，我们需要了解一个概念，那就是就是OSAL。什么是OSAL呢？可能大伙对于OS是比较了解的，学了计算机的搞过 OS的也基本接触过，简单来说就是一个操作系统抽象层，可以理 解为运行在CC2540上的操作系统，说操作系统还不能算，TI的OSAL只实现了任务切换和消息机制。并且把协议栈的代码、硬件处理的代码，用户程序的代码等分别放到了OSAL层的不同任务处理函数中去了，各任务函数之间通过消息机制、同一个任务之间通过事件的的方式来通信。什么是EVENT事件?OSAL为每个任务函数分配了一个 16位的事件变量，每一位代表一个事件，最高位为 0x800

2、0 表示为系统事件SYS_EVENT_MSG。其余的15位留给用户自定义需要的事件。通常事件由定时 器启动，比如一秒后我要点亮 LED2，这就需要发送一个点亮 LED2的事件，然后等待定时器1s后溢出，于是启动点亮LED2事件，事件会调用相应的hal层API点亮LED2。什么是MSG消息MSG是比EVENT事件更具体并且可以携带数据的一种通信方式，MSG的标记是按数值，而不是按位。比如 0x01和0x02 是两个不同的消息，但对于事件0x03则是0x01 事件和0x02事件的组合。MSG收发使用osal_msg_send()和 osal_msg_receive(); 当调用 osal_msg_

3、send()发送一个 msg 的同时会在 EVENT 列表中触发一个message ready event 。(请注意最后一句话，这句话点出了为什么按键时间的触发为何会导致系统事件 也接受到了)现在以SimpleBLEPeripheral为例说明按键流程在SimpleBLEPeripheral任务初始化函数中有这样一条代码:/ Register for all key events - This app will handle all key eventsRegisterForKeys( simpleBLEPeripheral_TasklD );这个函数来自OnBoard.c 源文件中/* *

4、 Keyboard Register function* The keyboard handler is setup to send all keyboard changes to * one task (if a task is registered).* If a task registers, it will get all the keys. You can change this * to register for individual keys.*/ uint8 RegisterForKeys( uint8 task_id )/ Allow only the first taski

5、f ( registeredKeysTaskID = NO_TASK_ID )registeredKeysTaskID = task_id;return ( true );elsereturn ( false );向一个全局变量registeredKeysTaskID中赋值自己的任务ID,调用了这个函数就能成功注册按键服务，那这个全局变量在何时使用呢？分析到这里，感觉有点迷糊了，我们可以从顶到下分析。任何一个程序都是从main函数开始的，这点我们要坚信。所以我们首先找到这个main函数打开SimpleBLEPeripheral_Main.c文件可以看至/* fnmain* briefStart

6、 of application.* paramnone* return none*/int main(void)/* Initialize hardware */HAL_BOARD_INIT();/ Initialize board I/OInitBoard( OB_COLD );/* Initialze the HAL driver */HalDriverInit();/* Initialize NV system */osal_snv_init();/* Initialize LL */* Initialize the operating system */ osalnit_system(

7、);/* Enable interrupts */HAL_ENABLE_INTERRUPTS();/ Final board initializationlnitBoard( OB_READY );#if defined ( POWER_SAVING )osal_pwrmgr_device( PWRMGR_BATTERY );#endif/* Start OSAL */osal_start_system(); / No Return from herereturn 0;我们打开InitBoard( OB_READY ); 可以看到如下代码/* fn InitBoard()* brief Ini

8、tialize the CC2540DB Board Peripherals* param level: COLD,WARM,READY* return None*/void InitBoard( uint8 level )if ( level = OB_COLD )/ Interrupts offosal_int_disable( INTS_ALL );/ Turn all LEDs offHalLedSet( HAL_LED_ALL, HAL_LED_MODE_OFF );/ Check for Brown-Out reset/ ChkReset();else / !OB_COLD/* I

9、nitialize Key stuff */OnboardKeylntEnable = HAL_KEY_INTERRUPT_ENABLE; /OnboardKeylntEnable = HAL_KEY_INTERRUPT_DISABLE;HalKeyConfig( OnboardKeylntEnable, OnBoard_KeyCallback);看到我上面标注的函数了吧？那个是一个按键回调服务注册函数，注册了一个OnBoard_KeyCallback 函数HalKeyConfig 函数的实现：将上述的回调函数的地址复制给了函数指针变量。通过跟踪发现该函数的指针变量在按键的轮询函数中调用了，如

10、下图:/* fnHalKeyPoll* brief Called by hal_driver to poll the keys* param None* * return None* void HalKeyPoll (void) uint8 keys = 0;|uint8 notify = 0;|#if defined (CC2540_MINIDK)/* Key is active low */if (!(HAL_KEY_SW_1_PORT & HAL_KEY_SW_1_BIT)/* Key is active low */#else/* Key is active low */if (!(H

11、AL_KEY_SW_6_PORT & HAL_KEY_SW_6_BIT)keys |= HAL_KEY_SW_6;if (HAL_KEY_JOY_MOVE_PORT & HAL_KEY_JOY_MOVE_BIT) /* Key is active HIGH */keys = halGetJoyKeylnput();#endif/* If interrupts are not enabled, previous key status and current key status* are compared to find out if a key has changed status.*/if

12、(!Hal_KeyIntEnable)if (keys = halKeySavedKeys)/* Exit - since no keys have changed */return;elsenotify = 1;else/* Key interrupt handled here */if (keys)notify = 1;/* Store the current keys for comparation next time */halKeySavedKeys = keys;/* Invoke Callback if new keys were depressed */if (notify &

13、 (pHalKeyProcessFunction)(pHalKeyProcessFunction) (keys, HAL_KEY_STATE_NORMAL);在这里底层的按键查询函数调用一个函数指针，而非具体的函数，这样就将处理按键的接口留给了上层，上层应用中, 另需解析的函数指针传入的参数1 : keys就知道是哪个按键被按下了。我们再回到刚才的 OnBoard_KeyCallback回调函数处，该回调函数代码如下：/* fn OnBoard_KeyCallback* brief Callback service for keys* param keys - keys that were p

14、ressed* state - shifted* return void*:void OnBoard_KeyCallback ( uint8 keys, uint8 state )uint8 shift; |(void)state;/ shift key (S1) is used to generate key interrupt/ applications should not use S1 when key interrupt is enabledshift = (OnboardKeyIntEnable = HAL_KEY_INTERRUPT_ENABLE) ? false : (keys

15、 & HAL_KEY_SW_6) ? true : false);if ( OnBoard_SendKeys( keys, shift ) != SUCCESS) /就是这句话将按键消息上传到应用层去处理的/ Process SW1 hereif ( keys & HAL_KEY_SW_1 ) / Switch 1/ Process SW2 hereif ( keys & HAL_KEY_SW_2 ) / Switch 2/ Process SW3 hereif ( keys & HAL_KEY_SW_3 ) / Switch 3/ Process SW4 hereif ( keys & HA

16、L_KEY_SW_4 ) / Switch 4/ Process SW5 hereif ( keys & HAL_KEY_SW_5 ) / Switch 5/ Process SW6 hereif ( keys & HAL_KEY_SW_6 ) / Switch 6/* If any key is currently pressed down and interruptis still enabled, disable interrupt and switch to polling */ if( keys != 0 ) |if( OnboardKeylntEnable = HAL_KEY_IN

17、TERRUPT_ENABLE ) OnboardKeyIntEnable = HAL_KEY_INTERRUPT_DISABLE;HalKeyConfig( OnboardKeyIntEnable, OnBoard_KeyCallback);/* If no key is currently pressed down and interrupt is disabled, enable interrupt and turn off polling */ elseif( OnboardKeylntEnable = HAL_KEY_INTERRUPT_DISABLE )OnboardKeylntEn

18、able = HAL_KEY_INTERRUPT_ENABLE;HalKeyConfig( OnboardKeylntEnable, OnBoard_KeyCallback);进入按键消息发送函数中可以看到:* fn*OnBoard_SendKeys* briefSend Key Pressed message to application.|* param keys - keys that were pressedstate - shifted* return status*uint8 OnBoard_SendKeys( uint8 keys, uint8 state )keyChange_

19、t *msgPtr;if ( registeredKeysTaskID != NO_TASK_ID )/ Send the address to the taskmsgPtr = (keyChange_t *)osal_msg_allocate( sizeof(keyChange_t);if ( msgPtr )msgPtr-hdr.event = KEY_CHANGE;msgPtr-state = state;msgPtr-keys = keys;osal_msg_send( registeredKeysTaskID, (uint8 *)msgPtr );return ( SUCCESS )

20、;elsereturn ( FAILURE );主要是将按键时间，状态和按键值打包到信息中最后通过osal_msg_send( registeredKeysTaskID, (uint8*)msgPtr );发送到注册了按键服务的应用层去，最终用户按了哪个按键，如何响应该按键在系统事件 SYS_EVENT_MSG 中处理。疑问又来了，为什么通过osal_msg_send收发的消息会出现在SYS_EVENT_MSG中呢？这个疑问，就是刚才我说过的osal_msg_send( registeredKeysTaskID, (uint8 *)msgPtr )会产生一个amessage ready eve

21、nt in the destination tasks event list./* fn osal_msg_send* brief* This function is called by a task to send a command message to* another task or processing element. The sending_task field must* refer to a valid task, since the task ID will be used* for the response message. This function will also

22、 set a message* ready event in the destination tasks event list.* paramuint8 destination_task - Send msg to Task ID* paramuint8 *msg_ptr - pointer to new message buffer* return SUCCESS, INVALID_TASK, INVALID_MSG_POINTER*/uint8 osal_msg_send( uint8 destination_task, uint8 *msg_ptr )return ( osal_msg_

23、enqueue_push( destination_task, msg_ptr, FALSE );/* fn simpleBLEPeripheral_ProcessOSALMsg* brief Process an incoming task message.* param pMsg - message to process* return none*/static void simpleBLEPeripheral_ProcessOSALMsg( osal_event_hdr_t *pMsg )switch ( pMsg-event )#if defined( CC2540_MINIDK )c

24、ase KEY_CHANGE:/按键处理事件，用户产生的按键都是在这里处理(keyChange_tsimpleBLEPeripheral_HandleKeys(keyChange_t*)pMsg)-state,*)pMsg)-keys );break;#endif / #if defined( CC2540_MINIDK )default:/ do nothing break;在SimpleBLEPeripheral 中，对按键的响应如下：joystick right(SW2)收发广播的开启和关闭/* fn simpleBLEPeripheral_HandleKeys* brief Handl

25、es all key events for this device.* param shift - true if in shift/alt.* param keys - bit field for key events. Valid entries:* HAL_KEY_SW_2* HAL_KEY_SW_1* return none*/static void simpleBLEPeripheral_HandleKeys( uint8 shift, uint8 keys ) uint8 SK_Keys = 0;VOID shift; / Intentionally unreferenced parameterif ( keys & HAL_KEY_SW_1 )SK_Keys |= SK_KEY_LEFT;if ( keys & HAL_KEY_SW_2 )SK_Keys |= SK_KEY_RIGHT;/ if device is not in a connection, pressing t