基于 HD7279 的键盘显示接口实验(C语言).doc

实验 基于 HD7279 的键盘显示接口实验一、实验目的1 掌握7279的工作原理和编程方法。2 掌握在MCS51系统中扩展7279键盘显示接口的方法。二、实验要求编写程序，利用7279及键盘显示接口电路，编程实现按键的读取，并将按键值显示在数码管上。三、芯片资料HD7279A 是一片具有串行接口的，可同时驱动8位共阴式数码管（或64只独立LED）的智能显示驱动芯片，该芯片同时还可连接多达64键的键盘矩阵，单片即可完成LED显示、键盘接口的全部功能。HD7279A内部含有译码器，可直接接受BCD码或16进制码，并同时具有2种译码方式，此外，还具有多种控制指令，如消隐、闪烁、左移、右移、段寻址等。HD7279A具有片选信号，可方便地实现多于8位的显示或多于64键的键盘接口。程序：#include void long_delay(void);void short_delay(void);void delay(unsigned char);void write(unsigned char, unsigned char);unsigned char read(unsigned char);void send_byte(unsigned char);unsigned char receive_byte(void);unsigned char j, k;unsigned int tmr;sbit cs=P14;sbit clk=P15;sbit dat=P12;sbit key=P32; #define RESET 0xa4#define TEST 0xbf#define DECODE0 0x80/下载数据方式0#define DECODE1 0xc8 /下载数据方式1#define READ 0x15#define UNDECODE 0x90#define RTL_CYCLE 0xa3#define RTR_CYCLE 0xa2#define RTL_UNCYL 0xa1#define RTR_UNCYL 0xa0#define ACTCTL 0x98 /xiaoyin#define SEGON 0xe0 /duanliang#define SEGOFF 0xc0#define BLINKCTL 0x88void main() send_byte(TEST);for (j=0;j3;j+) delay(100); send_byte(RESET);IP=0x01;/外部中断0高优先级EA=1; IT0=1; /外部中断0为下降沿触发 EX0=1; while (1);void T0ISR() interrupt 0 unsigned char k ,s,g,z; for (tmr=0;tmr0x2000;tmr+); send_byte(RESET); k=read(READ); g=k%10; s=k/10; send_byte(0x87); send_byte(s); send_byte(0x86); send_byte(g); delay(50); switch(k) case 0x01: for (tmr=0;tmr0x2000;tmr+); send_byte(RESET); write(UNDECODE+7,0x37);/ 不译码显示H delay(80); for (j=0;j23;j+) send_byte(RTR_CYCLE);/ 循环右移 delay(12); break;case 0x02: for (tmr=0;tmr0x2000;tmr+); send_byte(RESET); write(UNDECODE,0x37); delay(80); for (j=0;j23;j+) send_byte(RTL_CYCLE);/ 循环zuo移 delay(12); break;case 0x03: for (tmr=0;tmr0x2000;tmr+); send_byte(RESET); for (j=0;j16;j+) send_byte(RTL_UNCYL); write(DECODE0,j); delay(50); break;case 0x09: for (tmr=0;tmr0x2000;tmr+); send_byte(RESET); for (j=0;j16;j+) send_byte(RTR_UNCYL); write(DECODE1+7,j); delay(50); delay(100); break;case 0x0a: for (tmr=0;tmr0x2000;tmr+); send_byte(RESET); for (j=0;j16;j+) send_byte(RTR_UNCYL); write(DECODE1+7,j); delay(50); delay(150); z=0xff; for (j=0;j6;j+) z=z/2; write(ACTCTL,z);/ 加一个消隐位 delay(100); write(ACTCTL,0xff); break;case 0x11: for (tmr=0;tmr0x2000;tmr+); send_byte(RESET); for (j=0;j64;j+) write(SEGON,j);/ 将64个显示段逐个点亮 delay(20); break;case 0x12: for (tmr=0;tmr0x2000;tmr+); send_byte(RESET); for (j=0;j64;j+) write(SEGON,j);/ 将64个显示段逐个点亮 delay(20); for (j=0;j64;j+) write(SEGOFF,j);/ 将前一个显示段关闭 delay(20); break; default: break; void write(unsigned char cmd, unsigned char dta)send_byte (cmd);send_byte (dta);unsigned char read(unsigned char command)send_byte(command);return(receive_byte();void send_byte(unsigned char out_byte)unsigned char i;cs=0;long_delay(); /最少25微秒for (i=0;i8;i+)if (out_byte&0x80)dat=1;elsedat=0;clk=1;short_delay();clk=0;short_delay();out_byte=out_byte*2;dat=0;unsigned char receive_byte(void)unsigned char i, in_byte;dat=1;long_delay();for (i=0;i8;i+)clk=1;short_delay(); /输出键盘数据建立时间in_byte=in_byte*2;if (dat)in_byte=in_byte|0x01;clk=0;short_delay();dat=0;return (in_byte);void long_delay(void)unsigned char i;for (i=0;i0x30;i+);void