蓝桥杯单片机刷题——ADC测量电位器的电压

设计要求

通过PCF8591的ADC通道测量电位器RB2的输出电压，并使用套件上提供的USB转串口功能，完成下列程序设计要求。

串口每次接收包含5个字符的字符串，

1）若接收的5个字符中有字符’a’或’A’，则数码管显示一位小数电压值，指示灯L1点亮；

数码管显示格式如下：

电压：2.4V

2）若接收的5个字符中有字符’1’或’#’，则数码管显示两位小数电压值，指示灯L2点亮；

  数码管显示格式如下：

电压：2.41V

3）若不属于以上两种情况，则数码管显示整数电压值，指示灯全部熄灭。

  数码管显示格式如下：

电压：2V

备注：

单片机IRC振荡器频率设置为12MHz。

键盘模式：BTN；扩展模式：IO模式

串口波特率：9600bps

上电指示灯均处于熄灭状态，数码管默认显示整数。

数码管最高位固定显示字符’U’。

代码

sys.h

#ifndef __SYS_H__
#define __SYS_H__#include <STC15F2K60S2.H>
//iic.c
void get_Vrb2();
//sys.c
extern unsigned char Seg_Buff[8];
extern unsigned char UI;
extern float Vrb2;
void init74hc138(unsigned char n);
void init();
void Seg_Loop();
void seg_ui();#endif

main.c

#include "sys.h"
bit flag1=0;
bit flag2=0;
bit flag3=0;
unsigned char str[6];
void Timer0_Isr(void) interrupt 1
{static unsigned char count1=0;static unsigned int count2=0;count1++;count2++;if(count1==2){count1=0;flag1=1;}if(count2==1000){count2=0;flag2=1;}
}
void Timer0_Init(void)		//100微秒@12.000MHz
{AUXR |= 0x80;			//定时器时钟1T模式TMOD &= 0xF0;			//设置定时器模式TL0 = 0x50;				//设置定时初始值TH0 = 0xFB;				//设置定时初始值TF0 = 0;				//清除TF0标志TR0 = 1;				//定时器0开始计时ET0 = 1;				//使能定时器0中断EA=1;
}
void UartInit(void)		//9600bps@12.000MHz
{SCON = 0x50;		//8位数据,可变波特率AUXR |= 0x40;		//定时器时钟1T模式AUXR &= 0xFE;		//串口1选择定时器1为波特率发生器TMOD &= 0x0F;		//设置定时器模式TL1 = 0xC7;			//设置定时初始值TH1 = 0xFE;			//设置定时初始值ET1 = 0;			//禁止定时器中断TR1 = 1;			//定时器1开始计时ES=1;EA=1;
}
unsigned char choose_ui(unsigned char *str){unsigned char i;for(i=0;i<5;i++){if(str[i]=='A'||str[i]=='a') return 1;if(str[i]=='1'||str[i]=='#') return 2;}return 0;
}
void main(){init();Timer0_Init();UartInit();while(1){if(flag1){flag1=0;Seg_Loop();}if(flag2){flag2=0;get_Vrb2();seg_ui();}if(flag3){flag3=0;UI=choose_ui(str);seg_ui();}}
}
void uart() interrupt 4
{static unsigned char i=0;if(RI){RI=0;str[i]=SBUF;i++;if(i==5){i=0;flag3=1;}}
}

sys.c

#include "sys.h"
code unsigned char Seg_Table[]={0xC0, 0xF9 ,0xA4, 0xB0, 0x99 ,0x92 ,0x82 ,0xF8, 0x80 ,0x90,0xc1,//U 100xff //熄灭 11
};
unsigned char Seg_Buff[8]={11,11,11,11,11,11,11,11};
unsigned char UI=0;
float Vrb2;
void init74hc138(unsigned char n){P2=(P2&0x1f)|(n<<5);P2&=0x1f;
}
void init(){P0=0x00;init74hc138(5);P0=0xff;init74hc138(4);
}
void led(unsigned char addr){P0=~(0x01<<(addr-1));init74hc138(4);
}
void seg(unsigned char addr,num){P0=0xff;init74hc138(7);P0=0x01<<addr;init74hc138(6);P0=Seg_Table[num];if(UI!=0){if(UI==1){if(addr==6)P0&=0x7f;}else if(UI==2){if(addr==5)P0&=0x7f;}}init74hc138(7);
}
void Seg_Loop(){static unsigned char i=0;seg(i,Seg_Buff[i]);i++;if(i==8)i=0;
}
void ui0(){Seg_Buff[7]=(int)(Vrb2+0.005)%10;Seg_Buff[6]=11;Seg_Buff[5]=11;
}
void ui1(){Seg_Buff[7]=(int)(Vrb2*10+0.05)%10;Seg_Buff[6]=(int)(Vrb2+0.005)%10;Seg_Buff[5]=11;
}
void ui2(){Seg_Buff[7]=(int)(Vrb2*100+0.5)%10;Seg_Buff[6]=(int)(Vrb2*10+0.05)%10;Seg_Buff[5]=(int)(Vrb2+0.005)%10;
}
void seg_ui(){Seg_Buff[0]=10;switch(UI){case 0:ui0();led(9);break;case 1:ui1();led(1);break;case 2:ui2();led(2);break;//led(9)定为全部熄灭}
}

iic.c

#include "sys.h"
#include "intrins.h"
#define DELAY_TIME	10
sbit scl=P2^0;
sbit sda=P2^1;
//
static void I2C_Delay(unsigned char n)
{do{_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();		}while(n--);      	
}//
void I2CStart(void)
{sda = 1;scl = 1;I2C_Delay(DELAY_TIME);sda = 0;I2C_Delay(DELAY_TIME);scl = 0;    
}//
void I2CStop(void)
{sda = 0;scl = 1;I2C_Delay(DELAY_TIME);sda = 1;I2C_Delay(DELAY_TIME);
}//
void I2CSendByte(unsigned char byt)
{unsigned char i;for(i=0; i<8; i++){scl = 0;I2C_Delay(DELAY_TIME);if(byt & 0x80){sda = 1;}else{sda = 0;}I2C_Delay(DELAY_TIME);scl = 1;byt <<= 1;I2C_Delay(DELAY_TIME);}scl = 0;  
}//
unsigned char I2CReceiveByte(void)
{unsigned char da;unsigned char i;for(i=0;i<8;i++){   scl = 1;I2C_Delay(DELAY_TIME);da <<= 1;if(sda) da |= 0x01;scl = 0;I2C_Delay(DELAY_TIME);}return da;    
}//
unsigned char I2CWaitAck(void)
{unsigned char ackbit;scl = 1;I2C_Delay(DELAY_TIME);ackbit = sda; scl = 0;I2C_Delay(DELAY_TIME);return ackbit;
}//
void I2CSendAck(unsigned char ackbit)
{scl = 0;sda = ackbit; I2C_Delay(DELAY_TIME);scl = 1;I2C_Delay(DELAY_TIME);scl = 0; sda = 1;I2C_Delay(DELAY_TIME);
}
unsigned char adc(unsigned char addr){unsigned char temp;EA=0;I2CStart();I2CSendByte(0x90);I2CWaitAck();I2CSendByte(addr);I2CWaitAck();I2CStart();I2CSendByte(0x91);I2CWaitAck();temp=I2CReceiveByte();I2CSendAck(1);I2CStop();EA=1;return temp;
}
void get_Vrb2(){Vrb2=(float)adc(3)/255*5.0;
}

测评结果