main.c

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//通用AT89C51试验板驱动
//包括串口通信，键盘输入，三线串行通信
//P1口接4X4键盘。P1.0接键盘最右边插头。
//驱动程序包括：按键后串口发送键号0-F；三线接收；三线和串口接收后串口发送补码
//最后修改2004-12-18


//控制芯片AT89C51
#include <AT89X51.H> 

//3线串行通信
sbit CTRL=P3^2; //INT0
sbit CLK=P3^4;
sbit DATA=P3^5;

//4X4键盘扫描
sbit SCAN1=P1^4;
sbit SCAN2=P1^5;
sbit SCAN3=P1^6;
sbit SCAN4=P1^7;

//键盘定义

#define KEY1 0x0008 
#define KEY2 0x0080 
#define KEY3 0x0800 
#define KEY4 0x8000 
#define KEY5 0x0004 
#define KEY6 0x0040 
#define KEY7 0x0400
#define KEY8 0x4000
#define KEY9 0x0002
#define KEY0 0x0020  
#define KEYA 0x0200
#define KEYB 0x2000  
#define KEYC 0x0001  
#define KEYD 0x0010 
#define KEYE 0x0100
#define KEYF 0x1000 

//UART变量
bit flag_uart_busy;
unsigned char uartread,uartwrite; //已读取和已写入的指针
unsigned char uartbuf[8];//接收缓冲
unsigned char urvcmd;//接收的指令

//三线串行通信,与UART共用接收缓冲和指针
unsigned char ctrlsend,ctrlwrite;//发送指针 
unsigned char ctrlbuf[8];//发送缓冲

//时基 1280Hz 
#define RELOAD_HIGH 253 
#define RELOAD_LOW 70   
unsigned char tmrhigh,tmrlow;

//键盘输入
unsigned int nk;
bit flag_keyscan_en;

//其他变量
unsigned char delay1,delay2;
unsigned char ikey;

//按键常量
unsigned int code keys[16]={KEY0,KEY1,KEY2,KEY3,KEY4,KEY5,KEY6,KEY7,KEY8,KEY9,KEYA,KEYB,KEYC,KEYD,KEYE,KEYF};

/*************************
三线串行发送
**************************/
void sendtoctrl(unsigned char cmd){
	ctrlbuf[ctrlwrite]=cmd;
	if(++ctrlwrite==8) ctrlwrite=0;
	}
 

/**************************
main
***************************/

void main (void){

//启动延时
{unsigned int i;
	for(i=0;i<60000;i++){ 
		;}
	}


//初始化

//端口
	P0=0;
	P3=0xFF;

//timer0设置	
	TMOD|=0x01; //Timer0: 16-bit timer; 
	TH0=RELOAD_HIGH; 
	TL0=RELOAD_LOW;
	tmrhigh=RELOAD_HIGH;
	tmrlow=RELOAD_LOW;

//UART设置
	SCON = 0x50; // SCON: mode 1, 8-bit UART, enable rcvr 
	TMOD|= 0x20; // TMOD: timer 1, mode 2, 8-bit reload 
	PCON|=0x80;//	SMOD=1;speed double
	TL1=0xFD; //19200 baud rate
	TH1=0xFD; //19200 baud rate reload
	TXD=1;
	RXD=1;

//INT0中断设置
	IT0=1;//边沿触发

//中断设置
	EA=1; 
	ET0=1; //TIMER 0 enabled
	ET1=0; //TIMER 1 disabled
	ES=1;  //UART enabled	
	EX0=1; //INT0 enabled

//变量初始化
	uartread=0;
	uartwrite=0; 
	flag_uart_busy=0;

	ctrlsend=0;
	ctrlwrite=0;

	flag_keyscan_en=1;


//启动定时器
	TR0=1;
	TR1=1;


while (1) {
	
	
//uart communication
//uart  received 
if(uartread!=uartwrite){//uart cmd received
	if(++uartread>7) uartread=0;
	urvcmd=uartbuf[uartread];
	
	//add uart process code here

		while(flag_uart_busy){
			;}
		flag_uart_busy=1;
		SBUF=255-urvcmd;

	} //end of if

//end of uart

//-------------------------feedback code
/*
		sendtoctrl(FB_RAD10);
		while(flag_uart_busy){
			;}
		flag_uart_busy=1;
		SBUF=FB_RAD10;
		}
*/

//key input
if(!flag_keyscan_en){ //new input

	if(nk){

		//which key pressed
		ikey=0;
		while (!(nk&keys[ikey])){
			ikey++;
			}

		while(flag_uart_busy){
			;}
		flag_uart_busy=1;
		SBUF=ikey;

		}

//f(nk&KEY9){

	flag_keyscan_en=1;
	}
//end of key


	} //end of while(1)

}


/***************************************************
timer 0 interrupt
****************************************************/
void timer0(void) interrupt 1 using 1{

static signed char tick=0;
static unsigned char ctrlcmd=0,ctrlcmdbit=0;//3线串口发送字节，发送比特位置指针


//reload
    TR0=0; // stop T0
    TH0=tmrhigh; 
    TL0=tmrlow;
    TR0=1; // resume T0

//tick and key 
if(--tick<0){  //1/10s
	tick=128;
	delay1++;
	delay2++;

//key input
	if(flag_keyscan_en){
		unsigned char temp;
		nk=0;
		P1|=0x0F;  // all high
		SCAN1=0;  
		temp=P1&0x0F;
		nk=temp;

		SCAN1=1;
		SCAN2=0;
		temp=P1&0x0F;
		nk=nk*16+temp;
	
		SCAN2=1;
		SCAN3=0;
		temp=P1&0x0F;
		nk=nk*16+temp;

		SCAN3=1;
		SCAN4=0;
		temp=P1&0x0F;
		nk=nk*16+temp;
		SCAN4=1;

		nk=~nk;			//key pressed=bit set to 1
		flag_keyscan_en=0;  
		}//end of key scan
	} //end of tick

//send cmd to controller	

	if(ctrlcmdbit){ //is sending
		CLK=1;
		ctrlcmd>>=1;
		if(ctrlcmd&0x01) DATA=1;
		else DATA=0;
		if(++ctrlcmdbit==9){ //last(MSB) bit+1
			CTRL=1;			
			CLK=0;
			ctrlcmdbit=0;
			if(++ctrlsend==8) ctrlsend=0;
			EX0=1; //INT0 enabled
			DATA=1;
			CLK=1;
			}
		else CLK=0;
		}
	else if(ctrlsend!=ctrlwrite){ //cmd to be sent, bit=0;
		CLK=1;
		if(CLK==1) {//is not receiving	
			EX0=0; //INT0 disabled		
			CTRL=0;			
			ctrlcmd=ctrlbuf[ctrlsend];
			ctrlcmdbit++;
			if(ctrlcmd&0x01) DATA=1;
			else DATA=0;
			CLK=0;
			}			
		}



}


/***************************************************
uart interrupt
****************************************************/

void uart(void) interrupt 4 using 2{

if( TI){
	TI=0;
	}
if (RI){
	if(++uartwrite>7) uartwrite=0;
	uartbuf[uartwrite]=SBUF;
	RI=0;
	}
flag_uart_busy=0;

}
 
/***************************************************
INT0 interrupt
receive cmd from driver
****************************************************/
void int0(void) interrupt 0 using 3{
static unsigned char ctrlcmd=0;

	if(CLK==1) { //end of byte
		if(++uartwrite>7) uartwrite=0;
		uartbuf[uartwrite]=ctrlcmd;
		ctrlcmd=0;
		}
	else{
		ctrlcmd>>=1;
		if(DATA==1) ctrlcmd+=128;
		}

}