android蓝牙4.0(BLE)开发之ibeacon初步-白红宇

android蓝牙4.0(BLE)开发之ibeacon初步

阅读量：5122 次

发布时间：2019-06-13

本文共 6483 字，大约阅读时间需要 21 分钟。

一个april beacon里携带的信息如下

                         
<code 
class
=
" hljs "
>0201061AFF4C0002159069BDB88C11416BAC3F33468C2788A3044B0378C60C09417072696C426561636F6E051250002003020A0000000000000000000000</code>
        
      

具体是什么意思呢

                         
<code 
class
=
" hljs vhdl"
>
02
Number of bytes that follow in first AD structure
01
Flags AD type
06
    
Flags value 
0x1A
= 
000011010
       
bit 
0
(OFF) LE Limited Discoverable Mode
       
bit 
1
(ON) LE General Discoverable Mode
       
bit 
2
(OFF) BR/EDR Not Supported
       
bit 
3
(ON) Simultaneous LE and BR/EDR to Same Device Capable (controller)
       
bit 
4
(ON) Simultaneous LE and BR/EDR to Same Device Capable (Host)
1a Number of bytes that follow in second (and last) AD structure
前面是常规智能硬件广播包部分
ff （FF代表后面是Manufacture Data）
4c 
00
(组织标识，
0x4c00
苹果公司标识,https:
//www.bluetooth.org/en-us/specification/assigned-numbers/company-identifiers)
02
（
0x02
ibeacon标识位）
15
（
0x15
,
22
个字节标识长度，uuid，major，minor总和的长度）
90
69
bd b8-8c 
11
-
41
6b-ac 3f-
33
46
8c 
27
88
a3 (Proximity UUID)
04
4b(
1099
，major)
03
78
(
888
，minor)
c6  （切记这里是补码，转化为原码就是-
58
，iBeacon的信号发出强度值，用来作为和RSSI一起测距的基准 ，txPower）
        
计算
            
C6
            
1100
0110
补码
            
1100
0101
反码
            
1011
1010
原码
            
-（
32
+
16
+
8
+
2
）
            
-
58
0c09    （未知）
417072696c426561636f6e（AprilBeacon字符串对应的十六进制）
051250002003020a0000000000000000000000（未知）
</code>
        
      

Proximity UUID ：这是将你所有的beacon与其他人的beacon设备区别开的id！例如，目前在商店里某个区域分布着多个beacon形成一条“链带”，用于为顾客提供特定的服务，那么归属于同一条“链带”的beacon将分配到相同的proximity UUID。为这条“链带”设计的专用应用程序将会在后台使用这个UUID扫描到这条“链带”中的beacon设备。

major 编号：用于将相关的beacon标识为一组。例如，一个商店中的所有beacon将会分配到相同的major编号。通过这种方式，应用程序就能够知道顾客位于哪一家商店。

minor 标号：用于标识特定的beacon设备。例如一个商店中的每一个beacon设备都拥有唯一的minor编号，这样你才能够知道顾客位于商店中的哪个位置。

Measuring distance（测量距离）

最后一个值， TX power ，用于确定你和beacon之间距离有多近。根据这个值不但可以获得粗略的信息（比如靠近/远离/不在范围内等），也可以获取精确到米的距离（当然你也可以转换为以步为单位的距离）。那么如何实现？

TX power （上面例子中为0xC6=198，根据2的补码测得256-198=-58dBm）是距离设备1米测得的信号强度值（RSSI- Received Signal Strength Indication，接收到的信号强弱指标）。假如接收到的信号强度减弱了，那么我们可能在远离。只要知道1米距离的RSSI，以及当前的RSSI（我们可以从接收到的信号中一块获取到这些信息），那么计算出当前的距离是可能的。IOS已经实现了个这个功能，对于其它平台需要自己手动编码计算。

一个简单的测距函数

                         
<code 
class
=
"language-java hljs "
>
protected
static
double
calculateAccuracy(
int
txPower, 
double
rssi) { 
        
if
(rssi == 
0
) { 
            
return
-
1.0
; 
// if we cannot determine accuracy, return -1.
        
}
        
double
ratio = rssi * 
1.0
/ txPower;
        
if
(ratio < 
1.0
) { 
            
return
Math.pow(ratio, 
10
);
        
} 
else
{ 
            
double
accuracy = (
0.89976
) * Math.pow(ratio, 
7.7095
) + 
0.111
;
            
return
accuracy;
        
}
    
}</code>
        
      

在使用蓝牙时需要加权限

                         
<code 
class
=
"language-xml hljs "
> <uses-permission android:name=
"android.permission.BLUETOOTH"
>
    
<uses-permission android:name=
"android.permission.BLUETOOTH_ADMIN"
>
    
<uses-permission android:name=
"android.permission.RECEIVE_BOOT_COMPLETED"
>
</uses-permission></uses-permission></uses-permission></code>
        
      

关键代码如下

                         
<code 
class
=
"language-java hljs "
>
package
cn.edu.zafu.ble;
import
android.app.Activity;
import
android.bluetooth.BluetoothAdapter;
import
android.bluetooth.BluetoothDevice;
import
android.bluetooth.BluetoothManager;
import
android.content.Context;
import
android.content.Intent;
import
android.os.Bundle;
import
android.util.Log;
public
class
MainActivity 
extends
Activity { 
    
private
BluetoothAdapter mBluetoothAdapter;
    
@Override
    
protected
void
onCreate(Bundle savedInstanceState) { 
        
super
.onCreate(savedInstanceState);
        
setContentView(R.layout.activity_main);
        
BluetoothManager bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
        
mBluetoothAdapter = bluetoothManager.getAdapter();
        
if
(mBluetoothAdapter == 
null
|| !mBluetoothAdapter.isEnabled()) { 
            
Intent enableBluetooth = 
new
Intent(
                    
BluetoothAdapter.ACTION_REQUEST_ENABLE);
            
startActivityForResult(enableBluetooth, 
1
);
        
}
        
mBluetoothAdapter.startLeScan(mLeScanCallback);
    
}
    
private
BluetoothAdapter.LeScanCallback mLeScanCallback = 
new
BluetoothAdapter.LeScanCallback() { 
        
@Override
        
public
void
onLeScan(
final
BluetoothDevice device, 
final
int
rssi,
                
final
byte
[] scanRecord) { 
            
int
startByte = 
2
;
            
boolean
patternFound = 
false
;
            
// 寻找ibeacon
            
while
(startByte <= 
5
) { 
                
if
(((
int
) scanRecord[startByte + 
2
] & 
0xff
) == 
0x02
&& 
// Identifies
                                                                        
// an
                                                                        
// iBeacon
                        
((
int
) scanRecord[startByte + 
3
] & 
0xff
) == 
0x15
) { 
// Identifies
                                                                            
// correct
                                                                            
// data
                                                                            
// length
                    
patternFound = 
true
;
                    
break
;
                
}
                
startByte++;
            
}
            
// 如果找到了的话
            
if
(patternFound) { 
                
// 转换为16进制
                
byte
[] uuidBytes = 
new
byte
[
16
];
                
System.arraycopy(scanRecord, startByte + 
4
, uuidBytes, 
0
, 
16
);
                
String hexString = bytesToHex(uuidBytes);
                
// ibeacon的UUID值
                
String uuid = hexString.substring(
0
, 
8
) + 
"-"
                        
+ hexString.substring(
8
, 
12
) + 
"-"
                        
+ hexString.substring(
12
, 
16
) + 
"-"
                        
+ hexString.substring(
16
, 
20
) + 
"-"
                        
+ hexString.substring(
20
, 
32
);
                
// ibeacon的Major值
                
int
major = (scanRecord[startByte + 
20
] & 
0xff
) * 
0x100
                        
+ (scanRecord[startByte + 
21
] & 
0xff
);
                
// ibeacon的Minor值
                
int
minor = (scanRecord[startByte + 
22
] & 
0xff
) * 
0x100
                        
+ (scanRecord[startByte + 
23
] & 
0xff
);
                
String ibeaconName = device.getName();
                
String mac = device.getAddress();
                
int
txPower = (scanRecord[startByte + 
24
]);
                
Log.d(
"BLE"
,bytesToHex(scanRecord));
                
Log.d(
"BLE"
, 
"Name："
+ ibeaconName + 
"\nMac："
+ mac
                        
+ 
" \nUUID："
+ uuid + 
"\nMajor："
+ major + 
"\nMinor："
                        
+ minor + 
"\nTxPower："
+ txPower + 
"\nrssi："
+ rssi);
                
Log.d(
"BLE"
,
"distance："
+calculateAccuracy(txPower,rssi));
            
}
        
}
    
};
    
static
final
char
[] hexArray = 
"0123456789ABCDEF"
.toCharArray();
    
private
static
String bytesToHex(
byte
[] bytes) { 
        
char
[] hexChars = 
new
char
[bytes.length * 
2
];
        
for
(
int
j = 
0
; j < bytes.length; j++) { 
            
int
v = bytes[j] & 
0xFF
;
            
hexChars[j * 
2
] = hexArray[v >>> 
4
];
            
hexChars[j * 
2
+ 
1
] = hexArray[v & 
0x0F
];
        
}
        
return
new
String(hexChars);
    
}
    
protected
static
double
calculateAccuracy(
int
txPower, 
double
rssi) { 
        
if
(rssi == 
0
) { 
            
return
-
1.0
; 
// if we cannot determine accuracy, return -1.
        
}
        
double
ratio = rssi * 
1.0
/ txPower;
        
if
(ratio < 
1.0
) { 
            
return
Math.pow(ratio, 
10
);
        
} 
else
{ 
            
double
accuracy = (
0.89976
) * Math.pow(ratio, 
7.7095
) + 
0.111
;
            
return
accuracy;
        
}
    
}
}
</code>
        
      

至此，本文也就结束，所谓初步，就是获取ibeacon模块的基本信息。

源码

http://download.csdn.net/detail/sbsujjbcy/8503507

转载于:https://www.cnblogs.com/Free-Thinker/p/5560433.html

你可能感兴趣的文章