《KEY(按键)应用》大全

设计中你是否遇到过这样的问题：你的产品上要求有几十个按键，处理器IO口很少，PCB的面积又有严格限制，或者你要严格控制成本，无法使用象7219那样的扩展芯片，怎么解决这个问题？下面有个方法，大家都见过遥控器吧，上面不但有几十个按键，而且功能还挺多什么去抖动，同时按键处理都有了，最最重要的是控制芯片体积小，价格便宜（也就1，2块钱），外围器件少。

不过具体实现起来有点小麻烦，这类芯片的信号一般是PPM输出的，通常为了有更远的遥控距离，按键编码调制在一个38k 左右的载波上。

所以我们不得不再为这个方案多花上1块钱，加一个有烂运放做的低通滤波器，将载波滤除后在接到单片机的IO脚上，由于两个频率相差较多，这个滤波器并不难做。

我使用LM324做的。

其中有两级低通，一个比较器。

当你的示波器上出现一串可爱的几百赫兹的方波时，你的硬件就成功啦。

既然只用一条IO就扩展了几十个按键，软件上自然会多费些事，此类芯片发码都是有引导头，同步部分，用户码，键码等部分组成，有三十多个位，具体可参照sc6121资料。

下面时一个完整的接收程序，针对的芯片是sc6121，处理器89c51 ////////////////////////////////////////////////////////////////////////////////*定时器1中断服务程序*//*每100us中断一次,定时检测HangSignal线上的电平状态,根据6121的砝码格式译出用户码键码.\\ib_KeyCode[0] 用户码低位,ib_KeyCode[1]用户码高位,ib_KeyCode[2]键码,ib_KeyCode[3]键码的反码*//////////////////////////////////////////////////////////////////////////////////////void HandIn() interrupt 3 using 3 {unsigned char tempbit=0;bit Hbit;Hbit=HandSignal; /*采样信号线*/if (NewKey==FALSE){ /*如果上一次按键事件已经北处理*/ switch (ib_HandState){ /*根据接收状态散转*/case LEAD: /*引导头接收情况*/if (Hbit){ /*如果信号线是高电平*/if ((ib_LowTime>MIN_LeadTime)&&(ib_LowTime<MAX_LeadTime)) /*判断低电平时间是否合乎要求*/ib_HandState=START; /*正确进入同步头接收状态*/else ib_HandState=RESTART; /*否则复位接收程序*/ ib_LowTime=0; /*清除低电平时间计数*/}else{ /*如果信号是低电平*/ib_LowTime++; /*增加低电平时间计数器*/if (ib_LowTime>MAX_LeadTime) /*判断低电平时间是否超时*/ib_HandState=RESTART; /*是的话复位接收程序*/}break;case START: /*同步头接收情况*/if(Hbit){ /*如果信号线是高电平*/ib_HighTime++; /*高电平时间计数器加一*/if (ib_HighTime>MAX_SynTime) /*如果高电平时间超长,复位接收程序*/ib_HandState=RESTART;}else{ /*如果信号线是低电平*/if ((ib_HighTime>MIN_SynTime)&&(ib_HighTime<MAX_SynTime)) /*如果高电平时间合乎要求,将状态设定为数据为高电平检测*/ib_HandState=WAIT_HIGH;else ib_HandState=RESTART; /*否则复位接收程序*/ib_HighTime=0;}break;case WAIT_HIGH: /*等待数据位的上升沿的情况*/if (Hbit){ /*如果检测到一个上升沿*/if ((ib_LowTime>MIN_L_Time)&&(ib_LowTime<MAX_L_Time)) { /*如果低电平时间合乎要求,将状态设定为等待数据下降沿*/ib_HandState=WAIT_LOW;}else ib_HandState=RESTART; /*否则复位接收程序*/ib_LowTime=0;}else{ /*如果仍为低电平*/ib_LowTime++; /*低电平时间计数器加一*/if (ib_LowTime>MAX_L_Time) /*如果低电平时间超长,则复位寄售程序*/ib_HandState=RESTART;}break;case WAIT_LOW: /*等待数据下降沿的情况*/if (Hbit){ /*如果仍是高电平*/ib_HighTime++; /*高电平数据计数器加一*/ if (ib_HighTime>MAX_H_Time) /*如果高电平实际超长,则复位接收程序*/ib_HandState=RESTART;}else{ /*如果收到一个下降沿*/ib_KeyCode[ib_KeyPoint]>>=1; /*接收数据字节右移一位*/if ((ib_HighTime>MIN_B1TIME)&&(ib_HighTime<MAX_B1TIME)) { /*如果高电平宽度符合逻辑1标准,接收字节高位置一*/ib_KeyCode[ib_KeyPoint]+=0x80;}ib_BitCount++; /*接收数据位计数器加一*/if (ib_BitCount>7) { /*如果接收满一个字节*/ib_BitCount=0; /*清空位计数器*/ib_KeyPoint++; /*指向下一个字节*/if (ib_KeyPoint>3) /*如果接收完整个数据*/{//unsigned char i;NewKey=TRUE; /*置有新键按下标志*///for (i=0;i<4;i++){//TI=0;//SBUF=ib_KeyCode;//while(!TI);//TI=0;//}//ib_HandState=RESTART;}}ib_HighTime=0; /*将高电平时间计数器清零*/ib_HandState=WAIT_HIGH; /*设定系统为等待上升沿状态*/}break;default:break;}}if (ib_HandState==RESTART){ /*如果程序处于复位状态*/ib_LowTime=0; /*复位各项参数*/ib_HighTime=0;ib_HandState=LEAD;ib_KeyCode[0]=0; ib_KeyCode[1]=0;ib_KeyCode[2]=0; ib_KeyCode[3]=0;ib_KeyPoint=0;ib_BitCount=0;NewKey=FALSE;}}好多遥控器（无线，红外）发射数据都是PPM调制的，以上程序稍微改动后可以应用于各种PPM调制信号的场合。

4×4矩阵式键盘识别技术#include <AT89X51.H>unsigned char ID;void delay10ms(void){ unsigned char i,j;for(i=20;i>0;i--)for(j=248;j>0;j--);}void delay02s(void){ unsigned char i;for(i=20;i>0;i--){delay10ms();}}void main(void){ while(1){ if(P3_7==0){delay10ms();if(P3_7==0){ID++;if(ID==4){ID=0;}while(P3_7==0);}}switch(ID){ case 0:P1_0=~P1_0;delay02s();break; case1:P1_1=~P1_1;delay02s();break;case 2:P1_2=~P1_2;delay02s();break;case 3:P1_3=~P1_3;delay02s();break;}}}支持键盘双击事件的C程序设计！/********************************************************************************** KeyBoard Encode ProgramThis Program can encode press_key up to 128 and it can deal KB_DBClick MessageThis is just a test proram and only use 2 key.If More Key need to Encode ,pleasemodify the function:KBKeyPress()This Porgram use Message_Driver method,the KB_Msg is used to record what KB_Msg has occured.The meaning of 'SysKBMsg' is list as following.Program Design:LiBaizhanVer:1.10Date:2003-3-16************************************************************************************/#include <reg51.h>#include <intrins.h>sbit Key1 = P1^0;sbit Key2 = P1^1;/*Some System Var Pre_DefinitionCrystal Frequence is 11.0592MHz*/#define TIME_2MS 0X74#define TIME_20MS 0X043B#define KB_INTERNAL 3 /*Key DBClk Detection Internal *//*SysKBMsg define Keyboard Message,it include Single_Click or Double_ClickIt's bit6~bit0 record key_encode and bit 7 record DBClk(1) or SglClk(0)It can record and encode up to 127(2^7-1) keysNo key is press when it is 0This method did not deal key such as Ctrl_Key or Alt_Key or Shift_Key...etc.*//*_________________________________________________*/data unsigned char SysKBMsg=0; /*| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |*//*| D/S | KB6 | KB5 | KB4 | KB3 | KB2 | KB1 | KB0 |*/data unsigned char KBCounter=0;bit KBCounterStart=0;bit KBCounterStop=0; /*if KeyBoard counter stop then this bit is 1*/bit KBCounterFlag=0; /*Current Counter is used by KeyBoard*/void TimerInt0(void) interrupt 1 /*timer 0 interrupt use to record how long key is press*/{TR0=0;if(KBCounterFlag) /*Current Counter is used by KeyBoard*/{if(KBCounter<KB_INTERNAL) /*if DBClk Detection is not finish then detect continue*/{KBCounter++;TR0=1;}else{KBCounter=0; /*DBClk Detection is finish*/KBCounterStop=1;}}}void DelayMS(unsigned int dltime);void Init51(void);unsigned char KBKeyPress(void); /*only return what key is press*/void KBKeyEncode(void); /*encode which key is pressed and DBClk or SglClk*/void KBStartTimer(unsigned char CntH,unsigned char CntL); /*load counter initial value and start timer*/ void KBStopTimer(void);void KBDealPressKey(void); /*deal key_press message*/void main(void){Init51();while(1){KBKeyEncode(); /*recored what KeyBoard Msg occure:which key is press and single clk or db clk*/KBDealPressKey();}}/*Delay Time is :(20+17*dl_time)*12/CrystalFrequence(us)*/void DelayMS(unsigned int dltime){unsigned int i;for(i=0;i<dltime;i++);}void Init51(void){SCON = 0x50; /* mode 1: 8-bit UART, enable receiver */TMOD = 0x21; /* timer 1 mode 2: 8-Bit reload *//* timer 0 mode 1: 16-bit Timer */TH1 = BAUD_4800; /* reload value 9600 baud */TR1 = 1; /* timer 1 run */IE = 0X12; /* enable Serial INT,Timer0 INT */ES = 0; /* disable Serial INT*/EA = 1; /* Open INT Ctrl */}void KBKeyEncode(void){data unsigned char CurrPress=0,LastPress=0;if((LastPress=KBKeyPress())!=0) /*if some key is press then start encode*/{KBStartTimer(0,0); /*some key is press then start DBClk Detection Counter*/SysKBMsg=LastPress; /*record the key that is pressed this time*/while(!KBCounterStop){if((CurrPress=KBKeyPress())!=0X0) /*if some key is pressed during DBClk Detection then jump out to see wether DBclk is occured*/break;}if((KBCounterStop==0)&&(LastPress==CurrPress)) /*this key DBClk occured*/SysKBMsg|=0X80;KBStopTimer();}}unsigned char KBKeyPress(void){data unsigned char KeyPress=0;if((P1&0X03)!=0X03){DelayMS(TIME_20MS);if((KeyPress=(P1&0X03))!=0X03) /*some key is press*/{if(KBCounterStart)TR0=0;while((P1&0X03)!=0X03); /*wait until key is free*/DelayMS(TIME_20MS);if(KBCounterStart)TR0=1;}else /*Key is not real press*/{KeyPress=0;}}return KeyPress;}void KBStartTimer(unsigned char CntH,unsigned char CntL){TR0=0;TH0=CntH;TR0=1; /*Start Counter*/TL0=CntL;KBCounterFlag=1; /*this counter is used by KeyBoard*/KBCounterStart=1;KBCounterStop=0;}void KBStopTimer(void){TR0=0;TH0=0;TL0=0;KBCounter=0;KBCounterFlag=0;KBCounterStart=0;}void KBDealPressKey(void){data unsigned char tmp=0;switch(SysKBMsg) /*here is just a test program,test to deal Sgl_Clk and DB_Clk Msg*/ {case 0X01: tmp=0X01;break;case 0X02: tmp=0X02;break;case 0X81: tmp=0X81;break;case 0X82: tmp=0X82;break;default : break;}SysKBMsg=0; /*this key msg has been done*/96个key的零延时采集HotPower 发表于2003-11-5 18:04 侃单片机←返回版面;-------96键演示程序-------------------------;这是1个回复题中的应用示例,已通过软仿真“验证”;这只是键扫描技术的1个“缩影”,方法实在太多.;有“难看之处”,敬请高手们批评指教.;HotPower将虚心接受，坚决改正.重新做人.;发表目的: 在21IC中壮大游击队.;----------------------------------------------------;由于2051资源问题,本程序只取多任务键盘的压放键2个事件;废除长压键(压键1段时间后才激活)事件;废除长放键(放键1段时间后才激活)事件;废除双击键事件;废除任意组合键事件按键扫描驱动程序//按键扫描驱动程序unsigned char key,key_h,kpush;unsigned int key_l;//按键连接到p1.0、p1.1、p1.2void int_t0(void) interrupt 1 {unsigned char dd,i;TL0=TL0+30;TH0=0xfb; //800/* 按键判别*/if ((P1&0x7)==0x7) {if ((key_l>30)&&(key_l<800)&&(key_h>30)) { //释放按键，如果之前按键时间少于1秒，读入键值 key=kpush;}if ((++key_h)>200) key_h=200;key_l=0;if (key>=0x80) key=0; //如果之前的按键为长按1秒，清除键值} else {kpush=P1&0x7;key_l++;if ((key_l>800)&&(key_h>30)) { //如果按键超过1秒，键值加0x80标志长按键key=kpush|0x80;key_h=0;key_l=0;}}void main(void) {TMOD=0x1;TR0=1;ET0=1;EA=1; while (1) {while (!key) {}switch (key) {case 1:break;case 2:break;}}}键盘接口软件设计软件设计要考虑以下3部分内容：键盘缓冲区的设置；初始化程序；中断服务程序。