模拟串口全双工

/*由于mega16串口就一个在节省成本情况下应邀用普通IO口模拟串口通信，下面是128的实例程序，实现了全双工通信，不过占用两个定时器和一个外部中断资源，仅供考虑*//*作者：青檐铃风2012.5.13*/// Target : Mega128// Crystal: 8.0000Mhz#include<iom128v.h>#include<macros.h>#define U8 unsigned char#define bool unsigned char#define U16 unsigned int#define time1init TCNT1H=0XF9; TCNT1L=0X7D;//2400BIT/S 初值=0xFFFF-（1000000/baud/2）*8#define time3init TCNT3H=0XF9; TCNT3L=0X7D;//2400BIT/S/*++++++++++++++++++++++++++++++++++=宏定义=++++++++++++++++++++++++++++++++++++*/U8 vmRS232;// 记录模拟串口接收脚的高低电平// 脚定义#define GET_VM232_RX() (PIND &0x01) // 端口D的PD0模拟接收#define SET_VM232_TX() {PORTA|=BIT(0);} // 端口A的PA0发送#define CLR_VM232_TX() {PORTA&=~BIT(0);} // 端口A的PA0发送/*++++++++++++++++++++++=++++++++++++++++++++++++*/// 模拟串口的状态码enum {START,//接收起始位SDATA,//数据位STOP,//停止位标志U8 inRS232 = 0; // 模拟232的数据接收输入指针U8 outRS232 = 0; // 模拟232的数据接收取出指针U8 vmRS232Buf[20]={0}; // 模拟232的数据接收缓冲区U8 data=0;void delay(unsigned int x){unsigned int i,j;for(i=x;i>0;i--)for(j=0;j<330;j++);}void vm_rs232_rx(void) // 模拟232接收函数flag标志是否有接收到起始位{static U8 status = START;//静态变量每次进入时不会重新初始化static U8 cnt = 0;//三中取二的计数标志static U8 number = 0;//八位数据位标志static U8 rData;//读到的数据暂存地switch(status){case START:if(++cnt >=1){cnt = 0;number = 0;status = SDATA;}break;case SDA TA:if(++cnt >=2){cnt = 0;if((PIND&0x01)){rData |= 0x80;}else{rData &= 0x7F;}if(++number<8)//因为串口接收数据时从低位到高位的所以每次读出访在高位在一次右移一位{rData >>= 1;}if(number==8){number = 0;status = STOP;}}break;case STOP:if(++cnt>=1){cnt = 0;vmRS232Buf[inRS232++] =rData;//保存读到的数据if(inRS232==20)inRS232=0;PORTA|=BIT(1);status = START;//vmRS232=0;//取消读标志//TIMSK&=~BIT(2);//关定时器发送EIMSK=0x01; //开外部中断int_0,对应按键K20}break;default:cnt = 0;status = START;break;}}///////////////////////////////////////////发送函数/////////////////////////////bool flgVmRs232tx = 0; // 模拟232是否有数据要发送的标志，1有数据要发送，完成清零U8 vmRS232SBUF;// 模拟232要发送的一字节缓冲void vm_rs232_tx(void) // 模拟232发送函数{static U8 status = START;static U8 cnt = 0;static U8 number = 0;if(flgVmRs232tx){switch(status){case START:CLR_VM232_TX();if(++cnt >=2){cnt = 0;status = SDATA;}break;case SDA TA:if(vmRS232SBUF & 0x01){SET_VM232_TX();}else{CLR_VM232_TX();}if(++cnt >=2){cnt = 0;if(++number <=8){vmRS232SBUF >>= 1;}else{number = 0;status = STOP;}}break;case STOP:SET_VM232_TX();if(++cnt >=2){cnt = 0;status = START;flgVmRs232tx = 0;// ETIMSK&=~BIT(2);// 关中断//关了接收数据多了就会出错//EIMSK=0x01; //开外部中断int_0,对应按键K20}break;default:SET_VM232_TX();cnt = 0;status = START;flgVmRs232tx = 0;break;}}}// 波特率都是2400BIT/S ，416US/BIT// 3中取2 ，每208US抽样// 208US中断采样1个模拟串口void timer1_init(void){TCCR1B=0X01;//没分频2;//8M 8分频/// TCNT1H=0XFF;// TCNT1L=0X30;//38400BIT/S//30;2400BIT/Stime1initTIMSK|=BIT(2);// SREG|=BIT(7);}void timer3_init(void){TCCR3B=0X01;//没分频02;//8M 8分频/TCCR3A=0X00;//TCNT3H=0XFF;//TCNT3L=0X30;time3initETIMSK|=BIT(2);// SREG|=BIT(7);}/*+++++++++++++++++++++++++++++++++= MAIN =++++++++++++++++++++++++++++++++++++++*/void port_init(void){DDRA = 0x07;//PA0为输出口PORTA = 0x07;//PA0输出1DDRD = 0x00; //PD0输读入模拟rxdPORTD = 0x03;//PD0输入口上拉}void init_devices(void){//stop errant interrupts until set upCLI(); //disable all interruptsport_init();timer1_init();timer3_init();// MCUCR = 0x00;EICRA=0x00;//低电平触发成功2;//下降沿触发失败EIMSK=0x01; //开外部中断int_0,对应按键K20SEI();//re-enable interrupts//all peripherals are now initialized}void main(void){init_devices();// 收到什么就回发什么while(1){// while((PIND&0x02))while(flgVmRs232tx==1); //等待发送完再转载if(outRS232!=inRS232)//vmRS232SBUF!=data){vmRS232SBUF=vmRS232Buf[outRS232++];if(outRS232==20)outRS232=0;//TCNT3H=0XFF;//TCNT3L=0X30;time3init// data=vmRS232Buf[0];flgVmRs232tx=1;//ETIMSK|=BIT(2);//发送关了会不能及时接收数据长了会漏接}// }}}////////////////////////////////////////#pragma interrupt_handler ext_int0_isr:2 //指定外部中断函数void ext_int0_isr(void){// TCNT1H=0XFF;// TCNT1L=0X30;time1init//TIMSK&=~BIT(2);//TIMSK|=BIT(2);PORTA&=~BIT(1);vmRS232=1;//TIMSK|=BIT(2);EIMSK=0x00;//关外部中断int_0,对应按键K20}////////////////////////////////#pragma interrupt_handler time1_isr:15 //定时器1溢出void time1_isr(void){//TCNT1H=0XFF;// TCNT1L=0X30;time1init// 在这采样接收脚保证不漂移if(vmRS232)//判断是否需要读{vm_rs232_rx();}/* if(flgVmRs232tx){vm_rs232_tx();} */}#pragma interrupt_handler time3_isr:30//定时器3溢出void time3_isr(void){// TCNT3H=0XFF;// TCNT3L=0X30;time3init// 在这采样接收脚保证不漂移if(flgVmRs232tx){vm_rs232_tx();}}/*++++++++++++++++++++++++++++++++++=end=++++++++++++++++++++++++++++++ ++++++++++*/。