Pulse and body temperature monitor based on 51 single chip microcomputer

1. Hardware Solution

The system is based on the STC89C52 microcontroller. The photoelectric sensor uses the internal timer of the microcontroller system to calculate the time. The photoelectric sensor generates a signal. The microcontroller accumulates the signal to get the pulse beats. The time is obtained by the timer. During the operation of the system, the indicator light can be observed to flash. If it flashes evenly, it means that the measurement value is accurate. When the system stops running, the total pulse number can be displayed. In addition, we also added a temperature sensor DS18B20 to detect human body temperature.

It is mainly composed of 51 single chip microcomputer + 1602 LCD display + infrared tube collection + button + buzzer; as shown in the figure:

2. Design function

(1) This design is based on the STC89C51/52 (similar to AT89S51/52 and AT89C51/52) microcontroller.

(2) LCD1602 liquid crystal displays the current heart rate and current body temperature. The heart rate unit is heart rate/minute and the temperature unit is Celsius.

(3) Place your finger in the infrared tube and read your heart rate within 2 seconds; hold the temperature sensor in your hand to measure your current body temperature.

(4) Press the button to set the upper and lower limits of heart rate and body temperature for the alarm.

(5) Three buttons: one for setting, one for adding, and one for subtracting. Press the setting button to set the heart rate value, and press it again to set the temperature value;

3. Design Schematic

(1) The schematic diagram is mainly designed using AD software, as shown in the figure:

(2) The Protues simulation diagram is as follows:

(3) The PCB diagram is as follows:

4. Software Design

Main program source code

/********************Main function****************/

void main()

{

    ReadTemperature();

    show1(); //Display greetings and other information

time_init(); //Initialize the timer 

init_int0(); //External interrupt 0 initialization program

    init_eeprom(); //Read eeprom data

while(1)

{

      key(); //Key scan

      if(flat300ms>=4) //200ms

   {

    flat300ms=0;

//==================Main interface===================

  if(yemian==0)  

{

  if(biaozhi==0)

{

                   biaozhi=1;

   lcd_init(); // Initialization

   display(0x00,'H');

   display(0x01,'e');

   display(0x02,'a');

   display(0x03,'r');

   display(0x04,'t');

   display(0x05,':');

   display(0x40,'T');

   display(0x41,'e');

   display(0x42,'m');

   display(0x43,'p');

   display(0x44,':');

                 }

               wendumaibo();

   baojin();

       }

//==================Pulse alarm upper limit setting===================

  if(yemian==1)  

{

  if(biaozhi==1)

{

                   biaozhi=2;

   Buzzer=1;

   lcd_init(); // Initialization

   display(0x04,'H');

   display(0x05,'e');

   display(0x06,'a');

   display(0x07,'r');

   display(0x08,'t');

   display(0x09,'-');

   display(0x0a,'H');

display(0x46,S_heart_H/100+'0');

             display(0x47,S_heart_H%100/10+'0');

                 display(0x48,S_heart_H%100%10+'0');   

               }

                shezhi();

       }

//==================Pulse alarm lower limit setting===================

  if(yemian==2)  

{

  if(biaozhi==2)

{

                   biaozhi=3;

   Buzzer=1;

   lcd_init(); // Initialization

   display(0x04,'H');

   display(0x05,'e');

   display(0x06,'a');

   display(0x07,'r');

   display(0x08,'t');

   display(0x09,'-');

   display(0x0a,'L');

display(0x46,S_heart_L/100+'0');

             display(0x47,S_heart_L%100/10+'0');

                 display(0x48,S_heart_L%100%10+'0');   

               }

                shezhi();

       }

//==================Temperature alarm upper limit setting===================

  if(yemian==3)  

{

  if(biaozhi==3)

{

                   biaozhi=4;

   Buzzer=1;

   lcd_init(); // Initialization

   display(0x05,'T');

   display(0x06,'e');

   display(0x07,'m');

   display(0x08,'p');

   display(0x09,'-');

   display(0x0a,'H');

   display(0x46,S_temp_H/100+'0');

               display(0x47,S_temp_H%100/10+'0');

                   display(0x48,S_temp_H%100%10+'0');   

                }

                shezhi();

       }       

//==================Temperature alarm lower limit setting===================

  if(yemian==4)  

{

  if(biaozhi==4)

{

                   biaozhi=0;

   Buzzer=1;

   lcd_init(); // Initialization

   display(0x05,'T');

   display(0x06,'e');

   display(0x07,'m');

   display(0x08,'p');

   display(0x09,'-');

   display(0x0a,'L');

   display(0x46,S_temp_L/100+'0');

               display(0x47,S_temp_L%100/10+'0');

                   display(0x48,S_temp_L%100%10+'0');   

                }

                shezhi();

       }       

   }

    }

 }