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本文描述用新定义51单片机（RD8G37）+超声波一体测距传感器实现简单的测距测速仪。
测距仪演示效果
新定义RD8G37Q48RJ开发板
超声波测距模块：
8位并口屏
1、main.c
unsigned short timeConsuming=0;
unsigned int oldDistance;void rectClearScreen(void);void updateDisplay(void)
{unsigned int d[2];float v,dis;char buf[8]={0};memset(buf, '0', 8);Measure_Distance(d);dis=((float)d[0])/1000;sprintf(buf,"%0.f2d",dis); // 获取当前秒 buf[4]='\0'; if(d[0]<500){//rectClearScreen();GUI_WriteASCII_BIG(6,60,buf,VGA_YELLOW,VGA_RED);}else GUI_WriteASCII_BIG(6,60,buf,VGA_WHITE,VGA_BLACK);if(oldDistance>d[0])v=((float)(oldDistance-d[0]))/d[1];else v=(d[0]-oldDistance)/d[1];sprintf(buf,"%0.2f",v); // 获取当前秒 buf[4]='\0';GUI_WriteASCII(150,60,buf,VGA_Mint,VGA_BLACK);oldDistance=d[0];}void rectClearScreen(void)
{uint8_t i;setColor(VGA_RED);for(i=0;i<30;i+=3){drawRect(i+6,i*176/220+60,214-i,110-i*176/220);}
}
void draw_interface(void)
{setColor(VGA_BLACK);clrScr(VGA_BLACK);setColor(VGA_Orange_Red);fillRect(5,5,105,83);setColor(VGA_Golden);fillRect(115,5,215,83);setColor(VGA_Medium_Blue);fillRect(5,93,105,171);setColor(VGA_Mint);fillRect(115,93,215,171);GUI_Write32CnChar(10,10,"测距测速仪",VGA_Orange_Red,VGA_BLACK);GUI_Write32CnChar(118,113,"新定义",VGA_WHITE,VGA_Dark_Green);GUI_WriteASCII(20,145,"RD8G37Q48RJ",VGA_Dark_Mineral_Blue,VGA_BLACK);setColor(VGA_BLACK);fillRect(5,53,215,111);GUI_Write32CnChar(102,72,"米",VGA_WHITE,VGA_BLACK);GUI_WriteASCII(150,60,"1.1",VGA_Mint,VGA_BLACK);GUI_WriteASCII(165,82,"m/s",VGA_WHITE,VGA_BLACK);setColor(0XC618);drawRoundRect(0,0,219,175);
}
void main(void)
{ /*<Generated by EasyCodeCube begin>*//*<UserCodeStart>*//*<SinOne-Tag><36>*/IcResourceInit();InitLCD();setColor(VGA_BLACK);draw_interface();/*<UserCodeEnd>*//*<SinOne-Tag><36>*//*<UserCodeStart>*//*<SinOne-Tag><4>*//*****MainLoop*****/while(1){/*<UserCodeStart>*//*<SinOne-Tag><14>*//***User program***/updateDisplay();Delay(50000);/*<UserCodeEnd>*//*<SinOne-Tag><14>*//*<Begin-Inserted by EasyCodeCube for Condition>*/}/*<UserCodeEnd>*//*<SinOne-Tag><4>*//*<Generated by EasyCodeCube end>*/
}
2、传感器驱动
HC_SR04.c
#include "SC_Init.h"
#include "HC_SR04.h"extern unsigned int time;void Delay_us(unsigned short time)
{do{_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();}while(--time);}void HC_GPIO_Init(void)
{ResetTrig(); //Trig拉低，为输出脉冲触发信号做准备
}void Measure_Distance(unsigned int* distance) //测距
{//unsigned int distance[2]=0;SetTrig(); //10us的脉冲触发信号Delay_us(10);ResetTrig();while(HC_ECHO==0); //等待Echo输出高电平time=0; //开始记录回波信号脉宽while(HC_ECHO==1); //等待Echo输出低电平 distance[0]=time*1.7;//根据声速和时间计算距离，即distance=time*340/2/100distance[1]=time;/*关于分辨力(mm)：定时器每次对time加1是10us,10us=0.01ms,340m/s=340mm/ms计算距离时，最小分辨力为：0.01(ms) * 340(mm/ms) / 2 = 1.7(mm)小于模块标准精度3mm,故测距结果十分精准*/return ; //返回距离,单位mm
}HC_SR04.h
#ifndef _HC_SR04_H_
#define _HC_SR04_H_#define HC_TRIG P21
#define HC_ECHO P20
#define SetTrig() HC_TRIG=1
#define ResetTrig() HC_TRIG=0
//#define ReadEcho() GPIO_ReadPin(CW_GPIOB,GPIO_PIN_9)void HC_GPIO_Init(void);
void Measure_Distance(unsigned int* distance);#endif
3、初始化和中断
SC_Init.c，
初始化8位并口屏GPIO，TIMER0。
TIMER0设置为10us中断一次，做为距离传感器的测量时间最小单位。
void SC_Init(void)
{//Forbid editing areas before the following label !!!SC_GPIO_Init();SC_OPTION_Init();SC_TIM0_Init();/*write initial function here*/ EA = 1;
}/*****************************************************
*函数名称: SC_GPIO_Init
*函数功能: GPIO初始化函数
*入口参数：void
*出口参数：void
*****************************************************/
void SC_GPIO_Init(void)
{//Forbid editing areas before the following label !!!GPIO_Init(GPIO3, GPIO_PIN_6,GPIO_MODE_OUT_PP);GPIO_Init(GPIO3, GPIO_PIN_5,GPIO_MODE_OUT_PP);GPIO_Init(GPIO3, GPIO_PIN_4,GPIO_MODE_OUT_PP);GPIO_Init(GPIO3, GPIO_PIN_3,GPIO_MODE_OUT_PP);GPIO_Init(GPIO3, GPIO_PIN_2,GPIO_MODE_OUT_PP);GPIO_Init(GPIO3, GPIO_PIN_1,GPIO_MODE_OUT_PP);GPIO_Init(GPIO3, GPIO_PIN_0,GPIO_MODE_OUT_PP);GPIO_Init(GPIO1, GPIO_PIN_0,GPIO_MODE_OUT_PP);GPIO_Init(GPIO2, GPIO_PIN_0,GPIO_MODE_IN_HI);GPIO_Init(GPIO2, GPIO_PIN_1,GPIO_MODE_OUT_PP);GPIO_Init(GPIO0, GPIO_PIN_4,GPIO_MODE_OUT_PP);GPIO_Init(GPIO0, GPIO_PIN_5,GPIO_MODE_OUT_PP);GPIO_Init(GPIO0, GPIO_PIN_6,GPIO_MODE_OUT_PP);GPIO_Init(GPIO5, GPIO_PIN_1,GPIO_MODE_OUT_PP);GPIO_Init(GPIO5, GPIO_PIN_5,GPIO_MODE_OUT_PP);GPIO_Init(GPIO4, GPIO_PIN_7,GPIO_MODE_OUT_PP);/*GPIO_Init write here*/
}/*****************************************************
*函数名称: SC_TIM0_Init
*函数功能: TIMER0初始化函数
*入口参数：void
*出口参数：void
*****************************************************/
void SC_TIM0_Init(void)
{//Forbid editing areas before the following label !!!TIM0_TimeBaseInit(TIM0_PRESSEL_FSYS_D12,TIM0_MODE_TIMER);TIM0_WorkModeConfig(TIM0_WORK_MODE2,229, 0);TIM0_ITConfig(ENABLE,LOW);TIM0_Cmd(ENABLE);/*TIM0_Init write here*/
}
SC_it.c
TIMER0中断，每次中断计数加1。
void Timer0Interrupt() interrupt 1
{/*TIM0_it write here begin*///Forbid editing areas between the labels !!!/*TIM0_it write here*//*<Generated by EasyCodeCube begin>*//*<UserCodeStart>*//*<SinOne-Tag><55>*///Timer0Interrupt{/*<UserCodeStart>*//*<SinOne-Tag><15>*//***User program***/time++;/*<UserCodeEnd>*//*<SinOne-Tag><15>*//*<Begin-Inserted by EasyCodeCube for Condition>*/}/*<UserCodeEnd>*//*<SinOne-Tag><55>*//*<Generated by EasyCodeCube end>*//*Timer0Interrupt Flag Clear begin*///Forbid editing areas between the labels !!!/*Timer0Interrupt Flag Clear end*/
}总结
1、程序中用了TIMER0，主要是TIMER0可以做到us级，可以使测距更准确。
2、HC_SR04传感器的算法是通用的。
3、RD8G37Q48是QFN封装，PCB封装引脚延长到3mm，可以用烙铁焊接。
4、HC_SR04传感器不能测太远距离，室内3米以内应该没问题。
5、所用屏幕为ST7775，220*176分辨率，8位并口屏。
6、工程的建立用的是EasyCodeCube.exe，主要实现了gpio和timer初始化。程序编写和下载用的是keil。