Table of contents
1. Design background
Among the four diagnostic methods of TCM (look, smell, question, and feel), pulse diagnosis occupies a very important position. Pulse diagnosis is the most distinctive diagnostic method in traditional Chinese medicine. It has a long history and rich content. It is the embodiment and application of the basic spirit of "holistic concept" and "syndrome differentiation" in traditional Chinese medicine. The pulse carries a wealth of information about the health of the human body. Since the publication of the earliest pulse study monograph "Mai Jing" in my country in the third century AD, pulse diagnosis has attracted the attention of Chinese and foreign people as a means and method of "green non-invasive" diagnosis. However, because Chinese medicine relies on fingers to obtain pulse information, although pulse diagnosis is simple, non-invasive, and painless, it is easy to be accepted by patients, but some defects have also been exposed in long-term medical practice. First of all, the feature of distinguishing the pulse condition based on the feeling of the doctor's fingers alone is limited by feeling, experience and expression, and there are inevitably many subjective factors, which affect the standardization of pulse condition judgment. Secondly, this technique of cutting the pulse with fingers is difficult to master. Furthermore, the perceived pulse condition cannot be recorded and preserved, which affects the research on the pulse condition mechanism. The qualitative and subjectivity of pulse diagnosis has greatly affected its accuracy and feasibility, and has become a restrictive factor in the application, development and communication of pulse diagnosis in traditional Chinese medicine. In order to carry forward traditional Chinese medicine and promote the application and development of pulse diagnosis, it must be combined with modern technology to achieve a more scientific and objective diagnosis.
The nurses in the hospital have to take the pulse of the hospitalized patients every day and record the patient's pulse rate per minute. The method is to press the arteries in the patient's wrist with their hands and count according to the beating of the pulse. In order to save time, generally do not make a 1-minute measurement, usually measure the number of heartbeats in 10 seconds, and then multiply the result by 6 to get the number of heartbeats per minute, even if it is time-consuming, and the accuracy is not high . Therefore, it is very meaningful to develop a powerful pulse measuring instrument.
Two, realize the function
This topic has designed and completed a pulse measurement system based on 51 single-chip microcomputer . The system takes the STC89C52 single-chip microcomputer as the core, uses the 5mm photoelectric pair tube as the sensor (the frequency-adjustable square wave simulation is used in the simulation), uses the internal timer of the single-chip microcomputer system to calculate the time, and generates the pulse signal through the photoelectric pair tube and its related external circuits. Calculate the number of pulse beats by detecting the interval between two pulses, and display the pulse number on the LCD. The system realizes the functions of real-time monitoring and display of pulse, threshold value adjustment and over-limit alarm. The experimental results show that the system works normally, the measurement sensitivity is high, and the designed function is realized. The pulse measuring instrument designed this time mainly has the following functions:
- Has the basic characteristics of intelligent products;
- It has the functions of pulse detection and real-time display of the user;
- It has the alarm function of pulse number exceeding the limit;
- With button adjustment function, the upper and lower limit thresholds of the current pulse alarm can be adjusted;
3. Simulation demonstration
Adjust the lower threshold, the default lower threshold is 40.
Adjust the upper threshold, the default upper threshold is 100.
When the simulated pulse rate is 0.4Hz, the pulse rate measured by LCD1602 is 24BPM, which is lower than the lower threshold, the pulse rate is abnormal, and the buzzer will alarm.
When the simulated pulse frequency is 1Hz, the pulse rate measured by LCD1602 is 60BPM, which is higher than the lower threshold and lower than the upper threshold, the pulse rate is normal, and the buzzer does not alarm at this time. 
When the simulated pulse rate is 2Hz, the pulse rate measured by LCD1602 is 120BPM, which is higher than the upper limit threshold, the pulse rate is abnormal, and the buzzer will alarm.
4. Source program
#include <reg52.h>
#include <intrins.h>
#define uint unsigned int
#define uchar unsigned char
#define ulong unsigned long //宏定义
#define LCD_DATA P0 //定义P0口为LCD_DATA
sbit LCD_RS =P2^5;
sbit LCD_RW =P2^6;
sbit LCD_E =P2^7; //定义LCD控制引脚
sbit Xintiao =P1^0 ; //脉搏检测输入端定义
sbit speaker =P2^4; //蜂鸣器引脚定义
void delay5ms(void); //误差 0us
void LCD_WriteData(uchar LCD_1602_DATA); /********LCD1602数据写入***********/
void LCD_WriteCom(uchar LCD_1602_COM); /********LCD1602命令写入***********/
void lcd_1602_word(uchar Adress_Com,uchar Num_Adat,uchar *Adress_Data); /*1602字符显示函数，变量依次为字符显示首地址，显示字符长度，所显示的字符*/
void InitLcd();//液晶初始化函数
void Tim_Init();
uchar Xintiao_Change=0;
uint Xintiao_Jishu;
uchar stop;
uchar View_Data[3];
uchar View_L[3];
uchar View_H[3];
uchar Xintiao_H=100; //脉搏上限
uchar Xintiao_L=40; //脉搏下限
uchar num[10];
uint num_OK=0;
uchar XT=0;
uchar Key_Change;
uchar Key_Value; //按键键值
uchar View_Con; //设置的位（0正常工作，1设置上限，2设置下限）
uchar View_Change;
void main() //主函数
{
InitLcd();
Tim_Init();
lcd_1602_word(0x80,16,"Heart Rate: "); //初始化显示
TR0=1;
TR1=1; //打开定时器
while(1) //进入循环
{
if(Key_Change) //有按键按下并已经得出键值
{
Key_Change=0; //将按键使能变量清零，等待下次按键按下
View_Change=1;
switch(Key_Value) //判断键值
{
case 1: //设置键按下
{
View_Con++; //设置的位加
if(View_Con==3) //都设置好后将此变量清零
{
View_Con=0;
}
break; //跳出，下同
}
case 2: //加键按下
{
if(View_Con==2) //判断是设置上限
{
if(Xintiao_H<150) //上限数值小于150
{
Xintiao_H++; //上限+
}
}
if(View_Con==1) //如果是设置下限
{
if(Xintiao_L<Xintiao_H-1)//下限值小于上限-1（下限值不能超过上限）
{
Xintiao_L++; //下限值加
}
}
break;
}
case 3: //减键按下
{
if(View_Con==2) //设置上限
{
if(Xintiao_H>Xintiao_L+1)//上限数据大于下限+1（同样上限值不能小于下限）
{
Xintiao_H--; //上限数据减
}
}
if(View_Con==1) //设置下限
{
if(Xintiao_L>30) //下限数据大于30时
{
Xintiao_L--; //下限数据减
}
}
break;
}
}
}
if(View_Change)//开始显示变量
{
View_Change=0;//变量清零
if(stop==0) //心率正常时
{
if(View_Data[0]==0x30) //最高位为0时不显示
{
View_Data[0]=' ';
}
}
else //心率不正常（计数超过5000，也就是两次信号时间超过5s）不显示数据
{
View_Data[0]=' ';
View_Data[1]=' ';
View_Data[2]=' ';
}
switch(View_Con)
{
case 0: //正常显示
{
lcd_1602_word(0x80,16,"Heart Rate: ");//显示一行数据
lcd_1602_word(0xc0,16," ");//显示第二行数据
lcd_1602_word(0xcd,3,View_Data); //第二行显示心率
break;
}
case 1: //设置下限时显示
{
lcd_1602_word(0x80,16,"Heart Rate: ");//第一行显示心率
lcd_1602_word(0x8d,3,View_Data);
View_L[0]=Xintiao_L/100+0x30; //将下限数据拆字
View_L[1]=Xintiao_L%100/10+0x30;
View_L[2]=Xintiao_L%10+0x30;
if(View_L[0]==0x30) //最高位为0时，不显示
{
View_L[0]=' ';
}
lcd_1602_word(0xC0,16,"Warning L : ");//第二行显示下限数据
lcd_1602_word(0xCd,3,View_L);
break;
}
case 2: //设置上限时显示（同上）
{
lcd_1602_word(0x80,16,"Heart Rate: ");
lcd_1602_word(0x8d,3,View_Data);
View_H[0]=Xintiao_H/100+0x30;
View_H[1]=Xintiao_H%100/10+0x30;
View_H[2]=Xintiao_H%10+0x30;
if(View_H[0]==0x30)
{
View_H[0]=' ';
}
lcd_1602_word(0xC0,16,"Warning H : ");
lcd_1602_word(0xCd,3,View_H);
break;
}
}
}
}
}
void Time1() interrupt 3 //定时器1服务函数
{
static uchar Key_Con,Xintiao_Con;
uchar i,j;
uchar zancun;
bit flag_break;
TH1=0xd8; //10ms
TL1=0xf0; //重新赋初值
switch(Key_Con) //无按键按下时此值为0
{
case 0: //每10ms扫描此处
{
if((P3&0x07)!=0x07)//扫描按键是否有按下
{
Key_Con++; //有按下此值加1，值为1
}
break;
}
case 1: //10ms后二次进入中断后扫描此处（Key_Con为1）
{
if((P3&0x07)!=0x07)//第二次进入中断时，按键仍然是按下（起到按键延时去抖的作用）
{
Key_Con++; //变量加1，值为2
switch(P3&0x07) //判断是哪个按键按下
{
case 0x06:Key_Value=1;break; //判断好按键后将键值赋值给变量Key_Value
case 0x05:Key_Value=2;break;
case 0x03:Key_Value=3;break;
}
}
else //如果10ms时没有检测到按键按下（按下时间过短）
{
Key_Con=0; //变量清零，重新检测按键
}
break;
}
case 2: //20ms后检测按键
{
if((P3&0x07)==0x07) //检测按键是否还是按下状态
{
Key_Change=1; //有按键按下使能变量，（此变量为1时才会处理键值数据）
Key_Con=0; //变量清零，等待下次有按键按下
}
break;
}
}
switch (Xintiao_Con)//此处与上面按键的检测类似
{
case 0: //默认Xintiao_Con是为0的
{
if(!Xintiao)//每10ms（上面的定时器）检测一次脉搏是否有信号
{
Xintiao_Con++;//如果有信号，变量加一，程序就会往下走了
}
break;
}
case 1:
{
if(!Xintiao) //每过10ms检测一下信号是否还存在
{
Xintiao_Con++;//存在就加一
}
else
{
Xintiao_Con=0;//如果不存在了，检测时间很短，说明检测到的不是脉搏信号，可能是其他干扰，将变量清零，跳出此次检测
}
break;
}
case 2:
{
if(!Xintiao)
{
Xintiao_Con++;//存在就加一
}
else
{
Xintiao_Con=0;//如果不存在了，检测时间很短，说明检测到的不是脉搏信号，可能是其他干扰，将变量清零，跳出此次检测
}
break;
}
case 3:
{
if(!Xintiao)
{
Xintiao_Con++;//存在就加一
}
else
{
Xintiao_Con=0;//如果不存在了，检测时间很短，说明检测到的不是脉搏信号，可能是其他干扰，将变量清零，跳出此次检测
}
break;
}
case 4:
{
if(Xintiao)//超过30ms有信号，判定此次是脉搏信号，然后当信号消失后，执行以下程序
{
if(Xintiao_Change==1)//心率计原理为检测两次脉冲间隔时间计算心率，变量Xintiao_Change第一次脉冲时为0的，所有走下面的else，第二次走这里
{
if(60000/Xintiao_Jishu<200)
{
num[XT]=(60000/Xintiao_Jishu);
XT++;
if(XT>=5)
{
XT=0;
for(i=0;i<5;i++)
{
flag_break=0;
for(j=0;j<5;j++)
{
if(num[j]>num[j+1]) {zancun=num[j];num[j]=num[j+1];num[j+1]=zancun;flag_break=1;}
}
if(flag_break==0) break;
}
num_OK=(num[1]+num[2]+num[3]/*+num[5]+num[6]+num[7]*/)/3;
if((num_OK>=Xintiao_H)||(num_OK<=Xintiao_L))//心率不在范围内报警
speaker=0; //蜂鸣器响
else
speaker=1; //不响
}
View_Data[0]=num_OK/100+0x30; //计算心跳并拆字显示：心跳计时是以10ms为单位，两次心跳中间计数如果是100次，也就是100*10ms=1000ms=1s
View_Data[1]=num_OK%100/10+0x30; //那么计算出的一分钟（60s）心跳数就是：60*1000/（100*10ms）=60次 其中60是一分钟60s，1000是一秒有1000ms，100是计数值，10是一次计数对应 的时间是10ms
View_Data[2]=num_OK%10+0x30; //计算出的心跳数/100得到心跳的百位，%100是取余的，就是除以100的余数，再除以10就得到十位了，以此类推
//数字后的单个数据+0x30的目的是得到对应数字的液晶显示码，数字0对应的液晶显示码是0x30，1是0x30+1，以此类推
}
if(num_OK>200)
{
View_Data[0]='-';
View_Data[1]='-';
View_Data[2]='-';
speaker=1; //不响
// XT=0;
}
View_Change=1; //计算出心率后启动显示
Xintiao_Jishu=0; //心跳计数清零
Xintiao_Change=0; //计算出心率后该变量清零，准备下次检测心率
stop=0; //计算出心率后stop清零
}
else//第一次脉冲时Xintiao_Change为0
{
Xintiao_Jishu=0; //脉冲计时变量清零，开始计时
Xintiao_Change=1;//Xintiao_Change置1，准备第二次检测到脉冲时计算心率
}
Xintiao_Con=0; //清零，准备检测下一次脉冲
break;
}
}
}
}
/**定时器T0工作函数**/
void Time0() interrupt 1
{
TH0=0xfc; //1ms
TL0=0x18; //重新赋初值
Xintiao_Jishu++; //心跳计数加
if(Xintiao_Jishu==5000)//心跳计数大于5000
{
Xintiao_Jishu=0; //数据清零
View_Change=1; //显示位置1
Xintiao_Change=0; //置零，准备再次检测
stop=1; //心跳计数超过5000后说明心率不正常或者没有测出，stop置1
speaker=1; //关闭蜂鸣器
}
}
/**定时器初始化函数**/
void Tim_Init()
{
EA=1; //打开中断总开关
ET0=1; //打开T0中断允许开关
ET1=1; //打开T1中断允许开关
TMOD=0x11; //设定定时器状态
TH0=0xfc; //1ms
TL0=0x18; //赋初值
TH1=0xd8; //10ms
TL1=0xf0; //赋初值
}
/**在指定地址显示指定数量的指定字符**/
/**Adress_Com显示地址，Num_Adat显示字符数量，Adress_Data显示字符串内容**/
void lcd_1602_word(uchar Adress_Com,uchar Num_Adat,uchar *Adress_Data)
{
uchar a=0;
uchar Data_Word;
LCD_WriteCom(Adress_Com); //选中地址
for(a=0;a<Num_Adat;a++) //for循环决定显示字符个数
{
Data_Word=*Adress_Data; //读取字符串数据
LCD_WriteData(Data_Word); //显示字符串
Adress_Data++; //显示地址加一
}
}
/***************1602函数*******************/
void LCD_WriteData(uchar LCD_1602_DATA) /********LCD1602数据写入***********/
{
delay5ms(); //操作前短暂延时，保证信号稳定
LCD_E=0;
LCD_RS=1;
LCD_RW=0;
_nop_();
LCD_E=1;
LCD_DATA=LCD_1602_DATA;
LCD_E=0;
LCD_RS=0;
}
/********LCD1602命令写入***********/
void LCD_WriteCom(uchar LCD_1602_COM)
{
delay5ms();//操作前短暂延时，保证信号稳定
LCD_E=0;
LCD_RS=0;
LCD_RW=0;
_nop_();
LCD_E=1;
LCD_DATA=LCD_1602_COM;
LCD_E=0;
LCD_RS=0;
}
void InitLcd() //初始化液晶函数
{
delay5ms();
delay5ms();
LCD_WriteCom(0x38); //display mode
LCD_WriteCom(0x38); //display mode
LCD_WriteCom(0x38); //display mode
LCD_WriteCom(0x06); //显示光标移动位置
LCD_WriteCom(0x0c); //显示开及光标设置
LCD_WriteCom(0x01); //显示清屏
delay5ms();
delay5ms();
}
void delay5ms(void) //5ms延时函数
{
unsigned char a,b;
for(b=185;b>0;b--)
for(a=12;a>0;a--);
}
Pulse measuring instrument simulation source file and source program based on 51 single-chip microcomputer Baidu network disk link: Link: https://pan.baidu.com/s/1SmSCnLM7eEt0QqP1d88I8g
Extraction code: tv3h