《蓝桥杯真题》：2019年单片机省赛（第十届）

Posted 2022-11-25 Mascotttttt

2019年单片机省赛

• 有关题目
• 实现代码
• • main.c
  • iic.h
  • iic.c

有关题目

实现代码

注意：
频率测量功能：单片机 P34 引脚需与J3 排针上的 SIGNAL 引脚短接
限制条件方面：①切换通道注意初始化标志对应含义，例如，我代码中dac_flag为0时表示L5灯熄灭。
②定时器T0作为计数器时，除了中断溢出标志TF0可以不用外，TR0也得正常开启
③DAC输出时，注意写入的数字IIC_SendByte(temp)中temp范围在0~255;
处理数据：测量频率有可能会溢出，即uint无法存放过大频率(大于65535)，我们可以换用long 或unsigned long
源文件修改方面：官方给的iic.h中使用的时C51的头文件"reg52.h",我们需要修改为对应的15系列头文件"STC15F2K60S2.h"，这样才可以使用其中的一些特殊位寄存器
底层代码：①rd_pcf8591()函数读取最后需调用iic.c中IIC_SendAck()发送非应答信号，即SDA发送一个高电平
②DAC输出函数dac_pcf8591()在实现中需设置DA模式

main.c

#include "STC15F2K60S2.h"
#include "iic.h"

#define uchar unsigned char
#define uint unsigned int

sbit S7 = P3^0;
sbit S6 = P3^1;
sbit S5 = P3^2;
sbit S4 = P3^3;

sbit L1 = P0^0;
sbit L2 = P0^1;
sbit L3 = P0^2;
sbit L4 = P0^3;
sbit L5 = P0^4;


uchar jm = 0;//界面初始化电压界面
code uchar tab[] = 0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0xff, 0x8e, 0xc1; 
//F U 11 12

float Vrb2;
uchar Vdac = 2 * 51;//初始话DAC芯片输出固定电压值2.0V

//对应led，数码管，DAC控制。led_flag，smg_flag为0初始化led,数码管点亮，dac_flag为0初始L5熄灭
bit led_flag, smg_flag, dac_flag;
long cnt_freq, freq;//为了防止频率值过大，我们使用long类型

void sys_init();
void dac_pcf8591(uchar temp);//DAC输出
uchar rd_pcf8591(uchar addr);
void key_handle();
void led();

void dsp_smg_bit(uchar pos, val);
void display();//显示功能，分两个大块
void dsp_freq();
void dsp_vol();
void delay_k(uchar t);//延时t * 10us
void Delay1ms();		//1ms@12.000MHz，延时1ms用于给足数码管足够显示时间

void main()

	sys_init();
	while(1)
	
		Vrb2 = rd_pcf8591(0x43) * 5.0 / 255;
		key_handle();
		dac_pcf8591(Vdac);
		display();
		led();
	


void led()

	if (!led_flag)//led开
	
		uint V = (uint)(Vrb2 * 100);//Vrb2放大100倍便于比较
		if (0 == jm)
		
			P2 = (P2 & 0x1f) | 0x80;
			L1 = 0;
		
		else if (1 == jm)
		
			P2 = (P2 & 0x1f) | 0x80;
			L2 = 0;
		
		
		if ((V >= 150 && V < 250) || (V >= 350)	)
		
			P2 = (P2 & 0x1f) | 0x80;
			L3 = 0;
		
		
		if ((freq >= 1000 && freq < 5000) || freq >= 10000)
		
			P2 = (P2 & 0x1f) | 0x80;
			L4 = 0;
			
		
		if (dac_flag)
		
			P2 = (P2 & 0x1f) | 0x80;
			L5 = 0;
		
	
	else 
	
		P2 = (P2 & 0x1f) | 0x80;
		P0 = 0xff;
		P2 &= 0x1f;
		Delay1ms();
	




void key_handle()

	if(!S4)//切换模式
	
		delay_k(20);
		if (!S4)
		
			while(!S4)
				display();
			
			if (++jm >= 2)
				jm = 0;
		
	
	
	if(!S5)//dac输出模式切换
	
		delay_k(20);
		if (!S5)
		
			while(!S5)
				display();
			
			dac_flag = !dac_flag;
			if (!dac_flag)	
				Vdac = 2 * 51;
			else 
			
				Vdac = (uchar)(Vrb2 * 51);
			
		
	
	
	if(!S6)//led控制
	
		delay_k(20);
		if (!S6)
		
			while(!S6)
				display();
				
			led_flag = !led_flag;
		
	
	
	if(!S7)//数码管显示控制
	
		delay_k(20);
		if (!S7)
		
			while(!S7)
				display();
				
			smg_flag = !smg_flag;
			
		
	



void display()

	if (!smg_flag)
	
		if (0 == jm)
			dsp_vol();
		else if (1 == jm)
			dsp_freq();
	
	else 
	
		P2 = (P2 & 0x1f) | 0xc0;
		P0 = 0x00;
		
		P2 = (P2 & 0x1f) | 0xe0;
		P0 = 0xff;
		Delay1ms();
	



void dsp_vol()

	uint x = (uint)(Vrb2 * 100);
	dsp_smg_bit(1, 12);//U
	
	//第六6位添加小数点
	P2 = (P2 & 0x1f) | 0xc0;
	P0 = 1 << (6 - 1);
	
	P2 = (P2 & 0x1f) | 0xe0;
	P0 = tab[x / 100] & 0x7f;
	
	Delay1ms();
	P0 = 0xff;
	P2 &= 0x1f;
	
	dsp_smg_bit(7, x / 10 % 10);
	dsp_smg_bit(8, x % 10);


void dsp_freq()

	dsp_smg_bit(1, 11);//F
	if(freq > 99999)
		dsp_smg_bit(3, freq / 100000 % 10);
	if (freq > 9999)
		dsp_smg_bit(4, freq / 10000 % 10);
	if (freq > 999)
		dsp_smg_bit(5, freq / 1000 % 10);
	if (freq > 99)
		dsp_smg_bit(6, freq / 100 % 10);
	if (freq > 9)
		dsp_smg_bit(7, freq / 10 % 10);
	if (freq >= 0)
		dsp_smg_bit(8, freq % 10);


void dsp_smg_bit(uchar pos, val)

	P2 = (P2 & 0x1f) | 0xc0;
	P0 = 1 << (pos - 1);
	
	P2 = (P2 & 0x1f) | 0xe0;
	P0 = tab[val];
	
	Delay1ms();
	P0 = 0xff;
	P2 &= 0x1f;


void delay_k(uchar t)

	while(t--)
		display();


void Delay1ms()		//@12.000MHz

	unsigned char i, j;

	i = 12;
	j = 169;
	do
	
		while (--j);
	 while (--i);


void dac_pcf8591(uchar temp)

		IIC_Start();
		IIC_SendByte(0x90);
		IIC_WaitAck();

		IIC_SendByte(0x43);//DA模式
		IIC_WaitAck();

		IIC_SendByte(temp);
		IIC_WaitAck();
		IIC_Stop();
		//有时读取电压不成功可以延时5ms


uchar rd_pcf8591(uchar addr)

		uchar da;	
		IIC_Start();
		IIC_SendByte(0x90);
		IIC_WaitAck();

		IIC_SendByte(addr);
		IIC_WaitAck();
		IIC_Start();
		IIC_SendByte(0x91);
		IIC_WaitAck();

		da = IIC_RecByte();
		IIC_SendAck(1);
		IIC_Stop();

		return da;



void timer1() interrupt 3

	static uchar i1 = 0;
	
	if (++i1 == 20)//1s
	
		i1 = 0;
		freq = cnt_freq;
		cnt_freq = 0;
	



void timer0() interrupt 1

	cnt_freq++;


void sys_init()

	//关蜂鸣器，继电器
	P2 = (P2 & 0x1f) | 0xa0;
	P0 = 0xaf;
	
	P2 = (P2 & 0x1f) | 0x80;
	P0 = 0xff;
	P2 &= 0x1f;
	
	TMOD = 0x04;		//设置定时器模式，定时器0--计数器模式，定时器1--定时器模式
	
	TL0 = 0xff;
	TH0 = 0xff;//来一个脉冲就溢出计数一次
	TR0 = 1;
	
	//50ms
	TL1 = 0xB0;		//设置定时初值
	TH1 = 0x3C;		//设置定时初值
	TF1 = 0;		//清除TF1标志
	TR1 = 1;		//定时器1开始计时
	
	ET0 = 1;
	ET1 = 1;
	EA = 1;

iic.h

#ifndef _IIC_H
#define _IIC_H

#include "STC15F2K60S2.h"
#include "intrins.h"

sbit SDA = P2^1;
sbit SCL = P2^0;

void IIC_Start(void); 
void IIC_Stop(void);  
bit IIC_WaitAck(void);  
void IIC_SendAck(bit ackbit); 
void IIC_SendByte(unsigned char byt); 
unsigned char IIC_RecByte(void); 


#endif

iic.c

#include "iic.h"

#define DELAY_TIME 5

//I2C总线内部延时函数
void IIC_Delay(unsigned char i)

    do_nop_();
    while(i--);        


//I2C总线启动信号
void IIC_Start(void)

    SDA = 1;
    SCL = 1;
    IIC_Delay(DELAY_TIME);
    SDA = 0;
    IIC_Delay(DELAY_TIME);
    SCL = 0;	


//I2C总线停止信号
void IIC_Stop(void)

    SDA = 0;
    SCL = 1;
    IIC_Delay(DELAY_TIME);
    SDA = 1;
    IIC_Delay(DELAY_TIME);


void IIC_SendAck(bit ackbit)

    SCL = 0;
    SDA = ackbit;  					
    IIC_Delay(DELAY_TIME);
    SCL = 1;
    IIC_Delay(DELAY_TIME);
    SCL = 0; 
    SDA = 1;
    IIC_Delay(DELAY_TIME);


//等待应答
bit IIC_WaitAck(void)

    bit ackbit;
	
    SCL  = 1;
    IIC_Delay(DELAY_TIME);
    ackbit = SDA;
    SCL = 0;
    IIC_Delay(DELAY_TIME);
    return ackbit;


//I2C总线发送一个字节数据
void IIC_SendByte(unsigned char byt)

    unsigned char i;

    for(i=0; i<8; i++)
    
        SCL  = 0;
        IIC_Delay(DELAY_TIME);
        if(byt & 0x80) SDA  = 1;
        else SDA  = 0;
        IIC_Delay(DELAY_TIME);
        SCL = 1;
        byt <<= 1;
        IIC_Delay(DELAY_TIME);
    
    SCL  = 0;  


//I2C总线接收一个字节数据
unsigned char IIC_RecByte(void)

    unsigned char i, da;
    for(i=0; i<8; i++)
       
    	SCL = 1;
	IIC_Delay(DELAY_TIME);
	da <<= 1;
	if(SDA) da |= 1;
	SCL = 0;
	IIC_Delay(DELAY_TIME);
    
    return da;