CC2541 BLE源码阅读知识积累之外设从机Peripheral工作模式

一时失言乱红尘 2022-06-12 14:36 209阅读 0赞

转自：http://blog.csdn.net/zhjr1220/article/details/9416761

阅读的源代码：核心主要是位于BLE/project/SimpleBLEPeripheral部分

阅读的参考文档：TI\_BLE\_Software\_Developer's\_Guide.pdf，BLE\_CC2540\_DeepDive\_Training\_2011.pdf，TI\_BLE\_Sample\_Applications\_Guide.pdf，SIG的Core\_V4.0.pdf

在BLE的源码架构中，感觉是好复杂，还好TI对协议栈不开源，不然就得累死。能力有限只能把整个架构从最简单的主从工作模式入手。

1.BLE中主从机建立连接，到配对和绑定的过程如下图。

![20130508085338678][]

正如上图所示，最简单一次蓝牙通信需要以上相关步骤，包括discovery device,connect,pairing,bond等4个主要部分。

2.BLE中的GAP和GATT

初始接触，感觉十分的抽象，到现在为止，GAP个人认为就是监控上图中的交互状态，比如从广播变成连接，到配对等。

GATT通俗理解为用于主从机之间的客户端和服务器端的数据交互，以Attribute Table来体现。

GAP Role Profile:在GAP剧本里所处的4个角色：广播Advertise，主机central，从机Peripheral，观察者Observer。

GATT Attribute:通用属性配置文件。

3.SimpleBLEPeripheral\_Init函数解析。

无论是在主机还是从机，任何的蓝牙都将这部分内容作为自己的APPlication，在init中都会完成Bluetooth的GAP，GATT，SM等相关初始化。

void SimpleBLEPeripheral\_Init( uint8 task\_id )  
\{  
  simpleBLEPeripheral\_TaskID = task\_id;

// Setup the GAP Peripheral Role Profile  //GAP外设剧本  
  \{

\#if defined( CC2540\_MINIDK )  
      // For the CC2540DK-MINI keyfob, device doesn't start advertising until button is pressed  
      uint8 initial\_advertising\_enable = FALSE;  
    \#else  
      // For other hardware platforms, device starts advertising upon initialization  
      uint8 initial\_advertising\_enable = TRUE;//广播使能  
    \#endif

// By setting this to zero, the device will go into the waiting state after  
    // being discoverable for 30.72 second, and will not being advertising again  
    // until the enabler is set back to TRUE  
    uint16 gapRole\_AdvertOffTime = 0;

uint8 enable\_update\_request = DEFAULT\_ENABLE\_UPDATE\_REQUEST;//使能请求更新  
    uint16 desired\_min\_interval = DEFAULT\_DESIRED\_MIN\_CONN\_INTERVAL; //最小连接间隔0.1ms  
    uint16 desired\_max\_interval = DEFAULT\_DESIRED\_MAX\_CONN\_INTERVAL;  //最大连接间隔 1ms  
    uint16 desired\_slave\_latency = DEFAULT\_DESIRED\_SLAVE\_LATENCY;//0  
    uint16 desired\_conn\_timeout = DEFAULT\_DESIRED\_CONN\_TIMEOUT;//10s,定义该参数表示在该时间段内建立的连接不成功

// Set the GAP Role Parameters  
    GAPRole\_SetParameter( GAPROLE\_ADVERT\_ENABLED, sizeof( uint8 ), &initial\_advertising\_enable );  
    GAPRole\_SetParameter( GAPROLE\_ADVERT\_OFF\_TIME, sizeof( uint16 ), &gapRole\_AdvertOffTime );

GAPRole\_SetParameter( GAPROLE\_SCAN\_RSP\_DATA, sizeof ( scanRspData ), scanRspData );//当主机扫描到广播后会发出扫描请求，从机就发回该数据到主机  
    GAPRole\_SetParameter( GAPROLE\_ADVERT\_DATA, sizeof( advertData ), advertData );//广播参数

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 );  
  \}

// Set the GAP Characteristics, Set GAP GATT Server parameter  
  GGS\_SetParameter( GGS\_DEVICE\_NAME\_ATT, GAP\_DEVICE\_NAME\_LEN, attDeviceName );//GAP GATT服务器参数设置

// Set advertising interval  
  \{  
    uint16 advInt = DEFAULT\_ADVERTISING\_INTERVAL;

GAP\_SetParamValue( TGAP\_LIM\_DISC\_ADV\_INT\_MIN, advInt );  
    GAP\_SetParamValue( TGAP\_LIM\_DISC\_ADV\_INT\_MAX, advInt );  
    GAP\_SetParamValue( TGAP\_GEN\_DISC\_ADV\_INT\_MIN, advInt );  
    GAP\_SetParamValue( TGAP\_GEN\_DISC\_ADV\_INT\_MAX, advInt );  
  \}

// Setup the GAP Bond Manager   //GAP 绑定管理器设置  
  \{  
    uint32 passkey = 0; // passkey "000000"，密钥  
    uint8 pairMode = GAPBOND\_PAIRING\_MODE\_WAIT\_FOR\_REQ;//配对模式，配置成等待主机的配对请求  
    uint8 mitm = TRUE;  
    uint8 ioCap = GAPBOND\_IO\_CAP\_DISPLAY\_ONLY;  
    uint8 bonding = TRUE;  
    GAPBondMgr\_SetParameter( GAPBOND\_DEFAULT\_PASSCODE, sizeof ( uint32 ), &passkey );  
    GAPBondMgr\_SetParameter( GAPBOND\_PAIRING\_MODE, sizeof ( uint8 ), &pairMode );  
    GAPBondMgr\_SetParameter( GAPBOND\_MITM\_PROTECTION, sizeof ( uint8 ), &mitm );  
    GAPBondMgr\_SetParameter( GAPBOND\_IO\_CAPABILITIES, sizeof ( uint8 ), &ioCap );  
    GAPBondMgr\_SetParameter( GAPBOND\_BONDING\_ENABLED, sizeof ( uint8 ), &bonding );  
  \}

// Initialize GATT attributes  
  GGS\_AddService( GATT\_ALL\_SERVICES );            // GAP  
  GATTServApp\_AddService( GATT\_ALL\_SERVICES );    // GATT attributes  
  DevInfo\_AddService();                           // Device Information Service  
  SimpleProfile\_AddService( GATT\_ALL\_SERVICES );  // Simple GATT Profile  
\#if defined FEATURE\_OAD  
  VOID OADTarget\_AddService();                    // OAD Profile  
\#endif

// Setup the SimpleProfile Characteristic Values，对相关数值做初始化  
  \{  
    uint8 charValue1 = 1;  
    uint8 charValue2 = 2;  
    uint8 charValue3 = 3;  
    uint8 charValue4 = 4;  
    uint8 charValue5\[SIMPLEPROFILE\_CHAR5\_LEN\] = \{ 1, 2, 3, 4, 5 \};  
    SimpleProfile\_SetParameter( SIMPLEPROFILE\_CHAR1, sizeof ( uint8 ), &charValue1 );  
    SimpleProfile\_SetParameter( SIMPLEPROFILE\_CHAR2, sizeof ( uint8 ), &charValue2 );  
    SimpleProfile\_SetParameter( SIMPLEPROFILE\_CHAR3, sizeof ( uint8 ), &charValue3 );  
    SimpleProfile\_SetParameter( SIMPLEPROFILE\_CHAR4, sizeof ( uint8 ), &charValue4 );  
    SimpleProfile\_SetParameter( SIMPLEPROFILE\_CHAR5, SIMPLEPROFILE\_CHAR5\_LEN, charValue5 );  
  \}

\#if defined( CC2540\_MINIDK )

SK\_AddService( GATT\_ALL\_SERVICES ); // Simple Keys Profile

// Register for all key events - This app will handle all key events  
  RegisterForKeys( simpleBLEPeripheral\_TaskID );//注册按键，在这里当按键按下时，该任务会收到一个事件发来的消息

// makes sure LEDs are off  
  HalLedSet( (HAL\_LED\_1 | HAL\_LED\_2), HAL\_LED\_MODE\_OFF );

// For keyfob board set GPIO pins into a power-optimized state  
  // Note that there is still some leakage current from the buzzer,  
  // accelerometer, LEDs, and buttons on the PCB.

P0SEL = 0; // Configure Port 0 as GPIO  
  P1SEL = 0; // Configure Port 1 as GPIO  
  P2SEL = 0; // Configure Port 2 as GPIO

P0DIR = 0xFC; // Port 0 pins P0.0 and P0.1 as input (buttons),  
                // all others (P0.2-P0.7) as output  
  P1DIR = 0xFF; // All port 1 pins (P1.0-P1.7) as output  
  P2DIR = 0x1F; // All port 1 pins (P2.0-P2.4) as output

P0 = 0x03; // All pins on port 0 to low except for P0.0 and P0.1 (buttons)  
  P1 = 0;   // All pins on port 1 to low  
  P2 = 0;   // All pins on port 2 to low

\#endif // \#if defined( CC2540\_MINIDK )

\#if (defined HAL\_LCD) && (HAL\_LCD == TRUE)

\#if defined FEATURE\_OAD  
  \#if defined (HAL\_IMAGE\_A)  
    HalLcdWriteStringValue( "BLE Peri-A", OAD\_VER\_NUM( \_imgHdr.ver ), 16, HAL\_LCD\_LINE\_1 );  
  \#else  
    HalLcdWriteStringValue( "BLE Peri-B", OAD\_VER\_NUM( \_imgHdr.ver ), 16, HAL\_LCD\_LINE\_1 );  
  \#endif // HAL\_IMAGE\_A  
\#else  
  HalLcdWriteString( "BLE Peripheral", HAL\_LCD\_LINE\_1 );  
\#endif // FEATURE\_OAD

\#endif // (defined HAL\_LCD) && (HAL\_LCD == TRUE)

// Register callback with SimpleGATTprofile  
  VOID SimpleProfile\_RegisterAppCBs( &simpleBLEPeripheral\_SimpleProfileCBs );//给应用注册回调函数

// Enable clock divide on halt  
  // This reduces active current while radio is active and CC254x MCU  
  // is halted  
  HCI\_EXT\_ClkDivOnHaltCmd( HCI\_EXT\_ENABLE\_CLK\_DIVIDE\_ON\_HALT );

\#if defined ( DC\_DC\_P0\_7 )

// Enable stack to toggle bypass control on TPS62730 (DC/DC converter)  
  HCI\_EXT\_MapPmIoPortCmd( HCI\_EXT\_PM\_IO\_PORT\_P0, HCI\_EXT\_PM\_IO\_PORT\_PIN7 );

\#endif // defined ( DC\_DC\_P0\_7 )

// Setup a delayed profile startup  
  osal\_set\_event( simpleBLEPeripheral\_TaskID, SBP\_START\_DEVICE\_EVT );//标志SBP\_START\_DEVICE\_EVT启动该event

4.GAP部分的初始化和相关API以及，事件的处理过程。

在上3中的init中可以看到GAP作为Peripheral Role需要设置的核心参数如下

GAPROLE\_ADVERT\_ENABLED：广播使能。

GAPROLE\_ADVERT\_DATA：广播时的参数，

GAPROLE\_SCAN\_RSP\_DATA：从机扫描响应，返回的数据包

GAPROLE\_MIN\_CONN\_INTERVAL：处于连接状态后的设备，都会有个hop，一段时间内进行数据交互，以保证两者是连接的。当前后两次交互时，需要等待的最小间隔时间

GAPROLE\_MAX\_CONN\_INTERVAL：...需要等待的最大间隔时间

GAPROLE\_SLAVE\_LATENCY：处于连接后，从机可以做出不响应连接请求的间隔数目，即跳过n个交互的连接。

GAPROLE\_TIMEOUT\_MULTIPLIER：从上次成功连接到这次连接成功的最大允许延时。如果规定时间内未成功则认为本次连接失败，丢弃。该值必须比有效连接的间隔大。

GAPROLE\_PARAM\_UPDATE\_ENABLE：请求主机更新参数，主机可以接受也可以拒绝。

GAP通过在启动设备事件的任务处理中启动设备，其实主要是向GAP中注册回调函数，让系统在发现自身运行状态变化时，调用该函数，方便应用层进行相关操作。

VOID GAPRole\_StartDevice( &simpleBLEPeripheral\_PeripheralCBs );//启动设备，注册回调函数，用于监督设备的状态变化:广播、连接、配对、绑定等。

static void peripheralStateNotificationCB( gaprole\_States\_t newState )//传入参数由GPA自己输入，内部调用回调函数给用户  
  switch ( newState )  
  \{  
    case GAPROLE\_STARTED://在GAPRole\_StartDevice后发生状态变化  
      \{  
        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\[2\];

// set middle bytes to zero  
        systemId\[4\] = 0x00;  
        systemId\[3\] = 0x00;

// shift three bytes up  
        systemId\[7\] = ownAddress\[5\];  
        systemId\[6\] = ownAddress\[4\];  
        systemId\[5\] = ownAddress\[3\];

DevInfo\_SetParameter(DEVINFO\_SYSTEM\_ID, DEVINFO\_SYSTEM\_ID\_LEN, systemId);

\#if (defined HAL\_LCD) && (HAL\_LCD == TRUE)  
          // Display device address  
          HalLcdWriteString( bdAddr2Str( ownAddress ),  HAL\_LCD\_LINE\_2 );  
          HalLcdWriteString( "Initialized",  HAL\_LCD\_LINE\_3 );  
        \#endif // (defined HAL\_LCD) && (HAL\_LCD == TRUE)  
      \}  
      break;

case GAPROLE\_ADVERTISING:  
      \{  
        \#if (defined HAL\_LCD) && (HAL\_LCD == TRUE)  
          HalLcdWriteString( "Advertising",  HAL\_LCD\_LINE\_3 );  
        \#endif // (defined HAL\_LCD) && (HAL\_LCD == TRUE)  
      \}  
      break;

case GAPROLE\_CONNECTED:  
      \{  
        \#if (defined HAL\_LCD) && (HAL\_LCD == TRUE)  
          HalLcdWriteString( "Connected",  HAL\_LCD\_LINE\_3 );  
        \#endif // (defined HAL\_LCD) && (HAL\_LCD == TRUE)  
      \}  
      break;

case GAPROLE\_WAITING:  
      \{  
        \#if (defined HAL\_LCD) && (HAL\_LCD == TRUE)  
          HalLcdWriteString( "Disconnected",  HAL\_LCD\_LINE\_3 );  
        \#endif // (defined HAL\_LCD) && (HAL\_LCD == TRUE)  
      \}  
      break;

case GAPROLE\_WAITING\_AFTER\_TIMEOUT:  
      \{  
        \#if (defined HAL\_LCD) && (HAL\_LCD == TRUE)  
          HalLcdWriteString( "Timed Out",  HAL\_LCD\_LINE\_3 );  
        \#endif // (defined HAL\_LCD) && (HAL\_LCD == TRUE)  
      \}  
      break;

case GAPROLE\_ERROR:  
      \{  
        \#if (defined HAL\_LCD) && (HAL\_LCD == TRUE)  
          HalLcdWriteString( "Error",  HAL\_LCD\_LINE\_3 );  
        \#endif // (defined HAL\_LCD) && (HAL\_LCD == TRUE)  
      \}  
      break;

default:  
      \{  
        \#if (defined HAL\_LCD) && (HAL\_LCD == TRUE)  
          HalLcdWriteString( "",  HAL\_LCD\_LINE\_3 );  
        \#endif // (defined HAL\_LCD) && (HAL\_LCD == TRUE)  
      \}  
      break;

可以看到GAP Role 作为外设从机时，各种状态的变化，而这些状态 变化都由GAP（不开源部分）调用回调函数，将当前状态参数传入，以使得不同的APP做出反应。体现了一种回调函数设计的便捷性。

5.GATT Server的相关设置函数。

// Initialize GATT attributes  
  GGS\_AddService( GATT\_ALL\_SERVICES );            // GAP Service  
  GATTServApp\_AddService( GATT\_ALL\_SERVICES );    // GATT attributes  
  DevInfo\_AddService();                           // Device Information Service  
  SimpleProfile\_AddService( GATT\_ALL\_SERVICES );  // Simple GATT Profile

通常一个GATT中GAP server和GATT server是必须强制存在的（Mandatory）以及自己设计的profile server.

作为GATT的server和client，主要通过Attribute来进行交互，当client请求server读取数据时，通过如下注册的回调函数来进行访问。

// Register callback with SimpleGATTprofile  
  VOID SimpleProfile\_RegisterAppCBs( &simpleBLEPeripheral\_SimpleProfileCBs );//给应用注册回调函数

在回调函数中对时间做出处理。

[20130508085338678]: /images/20220612/e66ac50f4cea44bba5b350572a4a7b43.png