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iOS 蓝牙

时间:2016-07-03 19:55:01      阅读:222      评论:0      收藏:0      [点我收藏+]

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蓝牙协议本身经历了从1.0到4.0的升级演变, 最新的4.0以其低功耗著称,所以一般也叫BLE(Bluetoothlow energy)。

iOS 有两个框架支持蓝牙与外设连接。一个是 ExternalAccessory。从ios3.0就开始支持,也是在iphone4s出来之前用的比较多的一种模式,但是它有个不好的地方,External Accessory需要拿到苹果公司的MFI认证。

另一个框架则是本文要介绍的CoreBluetooth,在iphone4s开始支持,专门用于与BLE设备通讯(因为它的API都是基于BLE的)。这个不需要MFI,并且现在很多蓝牙设备都支持4.0,所以也是在IOS比较推荐的一种开发方法。

CoreBluetooth介绍

CoreBluetooth框架的核心其实是两个东西,peripheral和central, 可以理解成外设和中心。对应他们分别有一组相关的API和类,如下图所示:

技术分享

如果你要编程的设备是central那么你大部分用到,反之亦然。在我们这个示例中,金融刷卡器是peripheral,我们的iphone手机是central,所以我将大部分使用上图中左边部分的类。使用peripheral编程的例子也有很多,比如像用一个ipad和一个iphone通讯,ipad可以认为是central,iphone端是peripheral,这种情况下在iphone端就要使用上图右边部分的类来开发了。

服务和特征

有个概念有必要先说明一下。什么是服务和特征呢(service and characteristic)?

每个蓝牙4.0的设备都是通过服务和特征来展示自己的,一个设备必然包含一个或多个服务,每个服务下面又包含若干个特征。特征是与外界交互的最小单位。比如说,一台蓝牙4.0设备,用特征A来描述自己的出厂信息,用特征B来与收发数据等。

服务和特征都是用UUID来唯一标识的,UUID的概念如果不清楚请自行google,国际蓝牙组织为一些很典型的设备(比如测量心跳和血压的设备)规定了标准的service UUID(特征的UUID比较多,这里就不列举了),如下:

#define      BLE_UUID_ALERT_NOTIFICATION_SERVICE   0x1811  
 #define     BLE_UUID_BATTERY_SERVICE   0x180F  
 #define     BLE_UUID_BLOOD_PRESSURE_SERVICE   0x1810  
 #define     BLE_UUID_CURRENT_TIME_SERVICE   0x1805  
 #define     BLE_UUID_CYCLING_SPEED_AND_CADENCE   0x1816  
 #define     BLE_UUID_DEVICE_INFORMATION_SERVICE   0x180A  
 #define     BLE_UUID_GLUCOSE_SERVICE   0x1808  
 #define     BLE_UUID_HEALTH_THERMOMETER_SERVICE   0x1809  
 #define     BLE_UUID_HEART_RATE_SERVICE   0x180D  
 #define     BLE_UUID_HUMAN_INTERFACE_DEVICE_SERVICE   0x1812  
 #define     BLE_UUID_IMMEDIATE_ALERT_SERVICE   0x1802  
 #define     BLE_UUID_LINK_LOSS_SERVICE   0x1803  
 #define     BLE_UUID_NEXT_DST_CHANGE_SERVICE   0x1807  
 #define     BLE_UUID_PHONE_ALERT_STATUS_SERVICE   0x180E  
 #define     BLE_UUID_REFERENCE_TIME_UPDATE_SERVICE   0x1806  
 #define     BLE_UUID_RUNNING_SPEED_AND_CADENCE   0x1814  
 #define     BLE_UUID_SCAN_PARAMETERS_SERVICE   0x1813  
 #define     BLE_UUID_TX_POWER_SERVICE   0x1804  
 #define     BLE_UUID_CGM_SERVICE   0x181A  

当然还有很多设备并不在这个标准列表里,比如我用的这个金融刷卡器。蓝牙设备硬件厂商通常都会提供他们的设备里面各个服务(service)和特征(characteristics)的功能,比如哪些是用来交互(读写),哪些可获取模块信息(只读)等.

实现细节

作为一个中心要实现完整的通讯,一般要经过这样几个步骤:

建立中心角色—扫描外设(discover)—连接外设(connect)—扫描外设中的服务和特征(discover)—与外设做数据交互(explore and interact)—断开连接(disconnect)。

1建立中心角色

首先在我自己类的头文件中要包含CoreBluetooth的头文件,并继承两个协议<CBCentralManagerDelegate,CBPeripheralDelegate>,代码如下:
[objc] view plain copy 在CODE上查看代码片派生到我的代码片
#import <CoreBluetooth/CoreBluetooth.h>  
CBCentralManager *manager;  
manager = [[CBCentralManager alloc] initWithDelegate:self queue:nil];  

2扫描外设(discover)

代码如下:
[objc] view plain copy 在CODE上查看代码片派生到我的代码片
[manager scanForPeripheralsWithServices:nil options:options];

这个参数应该也是可以指定特定的peripheral的UUID,那么理论上这个central只会discover这个特定的设备,但是我实际测试发现,如果用特定的UUID传参根本找不到任何设备,我用的代码如下:
[objc] view plain copy 在CODE上查看代码片派生到我的代码片
NSArray *uuidArray = [NSArray arrayWithObjects:[CBUUID UUIDWithString:@"1800"],[CBUUID UUIDWithString:@"180A"],  
[CBUUID UUIDWithString:@"1CB2D155-33A0-EC21-6011-CD4B50710777"],[CBUUID UUIDWithString:@"6765D311-DD4C-9C14-74E1-A431BBFD0652"],nil];  

[manager scanForPeripheralsWithServices:uuidArray options:options];  

目前不清楚原因,怀疑和设备本身在的广播包有关。

3连接外设(connect)
当扫描到4.0的设备后,系统会通过回调函数告诉我们设备的信息,然后我们就可以连接相应的设备,代码如下:
[objc] view plain copy 在CODE上查看代码片派生到我的代码片
- (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI  
{  

    if(![_dicoveredPeripherals containsObject:peripheral])  
        [_dicoveredPeripherals addObject:peripheral];  

    NSLog(@"dicoveredPeripherals:%@", _dicoveredPeripherals);  
}  

//连接指定的设备  
-(BOOL)connect:(CBPeripheral *)peripheral  
{  
    NSLog(@"connect start");  
    _testPeripheral = nil;  

    [manager connectPeripheral:peripheral  
                       options:[NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES] forKey:CBConnectPeripheralOptionNotifyOnDisconnectionKey]];  

    //开一个定时器监控连接超时的情况  
    connectTimer = [NSTimer scheduledTimerWithTimeInterval:5.0f target:self selector:@selector(connectTimeout:) userInfo:peripheral repeats:NO];  

    return (YES);  
}  

4扫描外设中的服务和特征(discover)
同样的,当连接成功后,系统会通过回调函数告诉我们,然后我们就在这个回调里去扫描设备下所有的服务和特征,代码如下:

[objc] view plain copy 在CODE上查看代码片派生到我的代码片
- (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral  
{  
    [connectTimer invalidate];//停止时钟  

    NSLog(@"Did connect to peripheral: %@", peripheral);  
    _testPeripheral = peripheral;  

    [peripheral setDelegate:self];  
    [peripheral discoverServices:nil];  


}  

一个设备里的服务和特征往往比较多,大部分情况下我们只是关心其中几个,所以一般会在发现服务和特征的回调里去匹配我们关心那些,比如下面的代码:
[objc] view plain copy 在CODE上查看代码片派生到我的代码片
- (void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error  
{  


    NSLog(@"didDiscoverServices");  

    if (error)  
    {  
        NSLog(@"Discovered services for %@ with error: %@", peripheral.name, [error localizedDescription]);  

        if ([self.delegate respondsToSelector:@selector(DidNotifyFailConnectService:withPeripheral:error:)])  
            [self.delegate DidNotifyFailConnectService:nil withPeripheral:nil error:nil];  

        return;  
    }  


    for (CBService *service in peripheral.services)  
    {  

        if ([service.UUID isEqual:[CBUUID UUIDWithString:UUIDSTR_ISSC_PROPRIETARY_SERVICE]])  
        {  
            NSLog(@"Service found with UUID: %@", service.UUID);  
            [peripheral discoverCharacteristics:nil forService:service];  
            isVPOS3356 = YES;  
            break;  
        }  


    }  
}  

- (void)peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error   
{  

    if (error)   
    {  
        NSLog(@"Discovered characteristics for %@ with error: %@", service.UUID, [error localizedDescription]);  

        if ([self.delegate respondsToSelector:@selector(DidNotifyFailConnectChar:withPeripheral:error:)])  
            [self.delegate DidNotifyFailConnectChar:nil withPeripheral:nil error:nil];  

        return;  
    }  


    for (CBCharacteristic *characteristic in service.characteristics)  
    {  
        if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:UUIDSTR_ISSC_TRANS_TX]])  
        {  
            NSLog(@"Discovered read characteristics:%@ for service: %@", characteristic.UUID, service.UUID);  

            _readCharacteristic = characteristic;//保存读的特征  

            if ([self.delegate respondsToSelector:@selector(DidFoundReadChar:)])  
                [self.delegate DidFoundReadChar:characteristic];  

            break;  
        }  
    }  


    for (CBCharacteristic * characteristic in service.characteristics)  
    {  


        if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:UUIDSTR_ISSC_TRANS_RX]])  
        {  

            NSLog(@"Discovered write characteristics:%@ for service: %@", characteristic.UUID, service.UUID);  
            _writeCharacteristic = characteristic;//保存写的特征  

            if ([self.delegate respondsToSelector:@selector(DidFoundWriteChar:)])  
                [self.delegate DidFoundWriteChar:characteristic];  

            break;  


        }  
    }  

    if ([self.delegate respondsToSelector:@selector(DidFoundCharacteristic:withPeripheral:error:)])  
        [self.delegate DidFoundCharacteristic:nil withPeripheral:nil error:nil];  

}  

5与外设做数据交互(explore and interact)

发送数据很简单,我们可以封装一个如下的函数:
[objc] view plain copy 在CODE上查看代码片派生到我的代码片
//写数据  
-(void)writeChar:(NSData *)data  
{  
    [_testPeripheral writeValue:data forCharacteristic:_writeCharacteristic type:CBCharacteristicWriteWithResponse];  
}  

_testPeripheral和_writeCharacteristic是前面我们保存的设备对象和可以读写的特征。

然后我们可以在外部调用它,比如当然我要触发刷卡时,先组好数据包,然后调用发送函数:
[objc] view plain copy 在CODE上查看代码片派生到我的代码片
-(void)msrRead  
{  

    unsigned char command[512] = {0};  
    unsigned charchar *pTmp;  
    int nSendLen = 0;  
    unsigned char ucCrc[3] = {0};  

    _commandType = COMMAND_MSR_READ;  

    pTmp = command;  


    *pTmp = 0x02;//start  
    pTmp++;  

    *pTmp = 0xc1;//main cmd  
    pTmp++;  

    *pTmp = 0x07;//sub cmd  
    pTmp++;  



    nSendLen = 2;  

    *pTmp = nSendLen/256;  
    pTmp++;  
    *pTmp = nSendLen%256;  
    pTmp++;  

    *pTmp = 0x00;//sub cmd  
    pTmp++;  

    *pTmp = 0x00;//sub cmd  
    pTmp++;  


    Crc16CCITT(command+1,pTmp-command-1,ucCrc);  
    memcpy(pTmp,ucCrc,2);  


    NSData *data = [[NSData alloc] initWithBytes:&command length:9];  
    NSLog(@"send data:%@", data);  
    [g_BLEInstance.recvData setLength:0];  

    [g_BLEInstance writeChar:data];  
}  

比如说,你要交互的特征,它的properties的值是0x10,表示你只能用订阅的方式来接收数据。我这里是用订阅的方式,启动订阅的代码如下:
[objc] view plain copy 在CODE上查看代码片派生到我的代码片
//监听设备  
-(void)startSubscribe  
{  
    [_testPeripheral setNotifyValue:YES forCharacteristic:_readCharacteristic];  
}  

当设备有数据返回时,同样是通过一个系统回调通知我,如下所示:
[objc] view plain copy 在CODE上查看代码片派生到我的代码片
- (void)peripheral:(CBPeripheral *)peripheral didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error  
{  

    if (error)   
    {  
        NSLog(@"Error updating value for characteristic %@ error: %@", characteristic.UUID, [error localizedDescription]);  

        if ([_mainMenuDelegate respondsToSelector:@selector(DidNotifyReadError:)])  
            [_mainMenuDelegate DidNotifyReadError:error];  

        return;  
    }  

    [_recvData appendData:characteristic.value];  


    if ([_recvData length] >= 5)//已收到长度  
    {  
        unsigned charchar *buffer = (unsigned charchar *)[_recvData bytes];  
        int nLen = buffer[3]*256 + buffer[4];  
        if ([_recvData length] == (nLen+3+2+2))  
        {  
            //接收完毕,通知代理做事  
            if ([_mainMenuDelegate respondsToSelector:@selector(DidNotifyReadData)])  
                [_mainMenuDelegate DidNotifyReadData];  

        }  
    }  

}  

6 断开连接(disconnect)

这个比较简单,只需要一个API就行了,代码如下:

[objc] view plain copy 在CODE上查看代码片派生到我的代码片
//主动断开设备  
-(void)disConnect  
{  

    if (_testPeripheral != nil)  
    {  
        NSLog(@"disConnect start");  
        [manager cancelPeripheralConnection:_testPeripheral];  
    }  

} 


iOS 蓝牙

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原文地址:http://blog.csdn.net/airzingj/article/details/51791337

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