蓝桥杯单片机必备知识—–(5)独立按键

蓝桥杯单片机必备知识—–(5)独立按键

独立按键

注：在使用独立按键部分时，需将跳线帽放置BIT端

代码逻辑：

1.放在while（1）一直扫描按键是否按下
2.放在中断中 中断一次扫描按键是否按下
注：大型项目会放在中断中进行，一直扫描会占用过多资源，如果参加比赛则可以在while中一直使用循环

按键扫描函数

void read_key()
{
   
	uchar temp;  
	static unsigned state = 0;		//状态
	temp = P3 & 0x0f; 	//临时存储P3的状态
	switch(state)
	{
   
		case 0:{
   if(P3 != 0x0f) state = 1;}break;	//状态0，检测到有按键按下
		case 1:										//再次检测是否有按键按下，消抖
		{
   
			if(P3 != 0x0f){
   
			switch(temp)
			{
   
				case 0x0e:{
   s7++;state = 2;}break;	//如果S7按键对应的状态改变，则s7++
				case 0x0d:{
   s6++;state = 2;}break;	//如果S6按键对应的状态改变，则s7++
				case 0x0b:{
   s5++;state = 2;}break;	//如果S5按键对应的状态改变，则s7++
				case 0x07:{
   s4++;state = 2;}break;	//如果S4按键对应的状态改变，则s7++
			}
			}
			else state = 0;
		}break;
		case 2:{
   if(P3 == 0xff) state = 0;}break;	//检测按键是否抬起
	}
}

中断函数

void time0() interrupt 1
{
   
	static unsigned char intr = 0;
	display();
	if(++intr == 8) 	//按键消抖时间为5~10ms 
	{
   
		intr = 0;
		read_key();		//进行键扫描
	}
}

主函数内容不再赘述，如有不明白请看1,2中的内容

测试结果：

代码粘贴

#include <stc15f2k60s2.h>
#define uint unsigned int
#define uchar unsigned char
uchar tab[] = {
0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0xff};
uchar dspbuf[8] = {
10,10,10,10,10,10,10,10};
uchar s4 =0 ,s5 = 0,s6 = 0,s7 = 0;
void read_key();
void display();
void load();
void cls()
{

//关闭LED
P2 = (P2 & 0x1f) | 0x80;
P0 = 0xff;
P2 = 0x1f;
//关闭BUZZ
P2 = (P2 & 0x1f) | 0xa0;
P0 = 0x00;
P2 = 0x1f;
}
void main()
{

cls();
AUXR = 0x80;
TMOD = 0x80;
TL0 = 0xcd;
TH0 = 0xd4;
TR0 = 1;
ET0 = 1;
EA = 1;
while(1)
{
}
}
void time0() interrupt 1
{

static unsigned char intr = 0;
display();
if(++intr == 8) 	
{

intr = 0;
read_key();
}
}
void read_key()
{

uchar temp;
static unsigned state = 0;
temp = P3 & 0x0f;
switch(state)
{

case 0:{
if(P3 != 0x0f) state = 1;}break;
case 1:
{

if(P3 != 0x0f){

switch(temp)
{

case 0x0e:{
s7++;state = 2;}break;
case 0x0d:{
s6++;state = 2;}break;
case 0x0b:{
s5++;state = 2;}break;
case 0x07:{
s4++;state = 2;}break;
}
}
else state = 0;
}break;
case 2:{
if(P3 == 0xff) state = 0;}break;
}
}
void load()
{

dspbuf[0] = s4;
dspbuf[1] = s5;
dspbuf[2] = s6;
dspbuf[3] = s7;
dspbuf[4] = 10;
dspbuf[5] = 10;
dspbuf[6] = 10;
dspbuf[7] = 10;
}
void display()
{

static unsigned char dspcom = 0;
load();
P2 = (P2 & 0x1f) | 0xe0;
P0 = 0xff;
P2 = 0x1f;
P2 = (P2 & 0x1f) | 0xc0;
P0 = 1 << dspcom;
P2 = 0x1f;
P2 = (P2 & 0x1f) | 0xe0;
P0 = tab[dspbuf[dspcom]];
P2 = 0x1f;
if(++dspcom == 8) dspcom = 0;
}