曼码接收程序,常用在无线信号的编码与解码中,给大家分享:
rxi(){// this routine gets called every time TMR0 overflowsif(T0IF) //定时器中断程序
{TMR0 = PERIOD; // 装计时器初值
T0IF = 0; // 清定时器溢出标志
XTMR++; // 外部的系统时钟计时器加
1RFcount++; // 脉冲宽度计数器加1return;}if(RAIF) //端口电平变化中断程序
{if (RFFull) // 如果接收位满就退出
return;RFBit = RFIn; // 取样信号接收的值
RAIF = 0;switch (RFstate) // 当前状态
{case TRFDATAUP:switch (RFcount){ case 4:case 5: case 6:case 7:
PORTA = PORTA;//启动端口电平中断break;case 8:case 9:case 10:case 11:case 12:B[Bptr] = 1; // rotate if ( RFBit==0) //如是有效的下跳变则该位的数据值为1,上跳变为0{ B[Bptr]+=1; // shift in bit}if ( ( ++BitCount 7) == 0)Bptr++; // advance one byte if (BitCount == NBIT){RFstate = TRFreset; // finished receiving RFFull = 1;} RFcount=0; //重新记时PORTA = PORTA;//启动端口电平中断break;default: //超时或不足则退出接收RFstate = TRFSYNC; // reset state machine in all other casesRFcount = 0;Bptr = 0;BitCount = 0;PORTA = PORTA;//启动端口电平中断}break;case TRFSYNC:if ( RFBit){ // rising edge detected +---+ +---..// | | -Theader-> | // +----------------+if ( ( RFcount SHORT_HEAD) || ( RFcount >= LONG_HEAD)){RFstate = TRFreset;PORTA = PORTA;//启动端口电平中断break; // too short/long, no header}else{RFcount =0; // restart counterRFstate= TRFDATAUP;PORTA = PORTA;//启动端口电平中断}}else{ // still lowRFcount=0;PORTA = PORTA;//启动端口电平中断}break;case TRFreset:default:RFstate = TRFSYNC; // reset state machine in all other casesRFcount = 0;Bptr = 0;BitCount = 0;PORTA = PORTA;//启动端口电平中断break;} // switch} //电平中断 } // rxi void InitReceiver(){IOCA = 2;T0IF = 0;T0IE = 1; // TMR0 overflow interruptRAIE = 1; //使能端口电平变化中断GIE = 1; // enable interruptsRFstate = TRFreset; // reset state machine in all other casesRFFull = 0; // start with buffer emptyXTMR = 0; // start extended timerTMR0 = PERIOD; // 装计时器初值PORTA = PORTA;//启动端口电平中断}