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| // Function: This program can be used to measure heart rate, the lowest pulse in the program be set to 30.
// Use an external interrupt to measure it.
// Hardware: Grove - Ear-clip Heart Rate Sensor, Grove - Base Shield, Grove - LED
// Arduino IDE: Arduino-1.0
// Author: FrankieChu
// Date: Jan 22, 2013
// Version: v1.0
// by <a href="http://www.seeedstudio.com" target="_blank">www.seeedstudio.com</a>
#define LED 4//indicator, Grove - LED is connected with D4 of Arduino
boolean led_state = LOW;//state of LED, each time an external interrupt
//will change the state of LED
unsigned char counter;
unsigned long temp[21];
unsigned long sub;
bool data_effect=true;
unsigned int heart_rate;//the measurement result of heart rate
const int max_heartpluse_duty = 2000;//you can change it follow your system's request.
//2000 meams 2 seconds. System return error
//if the duty overtrip 2 second.
void setup()
{
pinMode(LED, OUTPUT);
Serial.begin(9600);
Serial.println("Please ready your chest belt.");
delay(5000);
arrayInit();
Serial.println("Heart rate test begin.");
attachInterrupt(0, interrupt, RISING);//set interrupt 0,digital port 2
}
void loop()
{
digitalWrite(LED, led_state);//Update the state of the indicator
}
/*Function: calculate the heart rate*/
void sum()
{
if(data_effect)
{
heart_rate=1200000/(temp[20]-temp[0]);//60*20*1000/20_total_time
Serial.print("Heart_rate_is:\t");
Serial.println(heart_rate);
}
data_effect=1;//sign bit
}
/*Function: Interrupt service routine.Get the sigal from the external interrupt*/
void interrupt()
{
temp[counter]=millis();
Serial.println(counter,DEC);
Serial.println(temp[counter]);
switch(counter)
{
case 0:
sub=temp[counter]-temp[20];
Serial.println(sub);
break;
default:
sub=temp[counter]-temp[counter-1];
Serial.println(sub);
break;
}
if(sub>max_heartpluse_duty)//set 2 seconds as max heart pluse duty
{
data_effect=0;//sign bit
counter=0;
Serial.println("Heart rate measure error,test will restart!" );
arrayInit();
}
if (counter==20&&data_effect)
{
counter=0;
sum();
}
else if(counter!=20&&data_effect)
counter++;
else
{
counter=0;
data_effect=1;
}
}
/*Function: Initialization for the array(temp)*/
void arrayInit()
{
for(unsigned char i=0;i < 20;i ++)
{
temp[i]=0;
}
temp[20]=millis();
} |
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