iOS 蓝牙-获取校验和

获取校验和方法

-(Byte)CalCheckSum2:(NSData*)data

{

   Byte chksum=0;

   Byte*byte=(Byte*)[databytes];

  for(NSUInteger i=0;i<[datalength];i++)

   {

     chksum+=byte[I];

   }

   returnchksum;

}

我的需求：指令是13位byte数组，最后一位是前面十二位的校验和，第三四位是时间（24小时制）小时和分钟转换成的byte字节，其他的都是固定的指令。我的构造方法是

//防盗器 定时充电指令

-(void)onTimeChargeByBlueWith:(NSString*)timeStr

{

NSArray*array=[timeStr componentsSeparatedByString:@":"];

Byte onTimeChargeOrder[13]={0};

onTimeChargeOrder[0]=0xB9;

onTimeChargeOrder[1]=0x60;

onTimeChargeOrder[2]=[self  getByteWithIntString:array[0]];

onTimeChargeOrder[3]=[self getByteWithIntString:array[1]];

onTimeChargeOrder[4]=0x00;

onTimeChargeOrder[5]=0x00;

onTimeChargeOrder[6]=0x00;

onTimeChargeOrder[7]=0x00;

onTimeChargeOrder[8]=0x00;

onTimeChargeOrder[9]=0x00;

onTimeChargeOrder[10]=0x00;

onTimeChargeOrder[11]=0x00;

onTimeChargeOrder[12]=[self  CalCheckSum2:[NSData  dataWithBytes:onTimeChargeOrder  length:12]];

NSData*data=[NSData dataWithBytes:&onTimeChargeOrder length:sizeof(onTimeChargeOrder)];

NSLog(@"构造完的数据是 %@",data);//这里可以拿到data，然后对蓝牙的peripheral对象调用writeValue方法// [self.currPeripheral writeValue:data forCharacteristic:self.characteristic type:CBCharacteristicWriteWithResponse];

}

#pragmamark-----------工具方法----------------

-(Byte)getByteWithIntString:(NSString*)intString

{

inthourInt=[intString intValue];

Byte hourByte[4]={0};

hourByte[0]=(char)(hourInt>>24&0xff);

hourByte[1]=(char)((hourInt>>16)&0xff);

hourByte[2]=(char)((hourInt>>8)&0xff);

hourByte[3]=(char)((hourInt)&0xff);

return(char)((hourInt)&0xff);

}

// 获取校验和

-(Byte)CalCheckSum2:(NSData*)data

{

Byte chksum=0;

Byte*byte=(Byte*)[data bytes];

for(NSUInteger i=0;i<[data length];i++){

   chksum+=byte[I];

}

returnchksum;

}

最后调用方法

[self onTimeChargeByBlueWith:@"13:45"];

得到的数据为

2017-03-11 11:23:21.211 test0227[92358:2093146] 构造完的数据是 <b9600d2d 00000000 00000000 53>