This code is used to detect sighs from a patient and send a signal to a mobile device. It reads analog sensor data to calculate a sliding average breath value and compare it to a threshold. When the average exceeds the threshold for a possible sigh, it monitors for the average to drop below a level to confirm the sigh. Upon detection, it sends a signal over a serial connection and lights an LED for one second.

1. /*
Michael Kontopoulos
2009
Sigh Collector - Sender Code
*/
#include <NewSoftSerial.h>
NewSoftSerial mySerial = NewSoftSerial(4, 5); //instead of 1,2 (rx,tx)
//PINS
int stretcher = 1;
int threshPin = 0;
int threshLed=3;
int val = 0; // variable to store the value coming from the sensor
int pot = 0;
int sighPin = 13;
//VARIABLES
int const numVals = 40;
int breathVals[numVals];
//int diffVals[numVals/4];
int total=0, diffTotal=0, avg=0, rate=0;
int state = 0;
int threshold=0;
int normBreath;
int prevMillis=0;
boolean possibleSigh;
void setup() {
Serial.begin(9600);
mySerial.begin(9600);
pinMode(sighPin, OUTPUT);
pinMode(stretcher, INPUT);
possibleSigh = false;
}
void loop() {
serialHandler();
val = analogRead(stretcher);
threshold = analogRead(threshPin);
// Serial.println(val);
checkSigh(avg);
//Array of the last 30 breath values
for(int i=1; i<numVals; i++)
{
//Shift the values down
breathVals[i-1] = breathVals[i];
//Add the most recent value to the last element
breathVals[numVals-1] = val;
//Obtaining the sliding scale average
//First add up all the values in the array
total += abs(breathVals[i-1]);
//Average them
avg = total/numVals;

2. }
total=0;
diffTotal=0;
//PRINT TESTS
Serial.print("Average Value: ");
Serial.print(avg);
Serial.print("tThreshold: ");
Serial.println(threshold);
if((avg >= threshold) && (avg < 400))
{
// digitalWrite(threshLed, HIGH);
possibleSigh = true;
}
else {
//digitalWrite(threshLed, LOW);
}
}
long int prevMillz = 0;
void checkSigh(int average)
{
if(possibleSigh)
{ prevMillis = millis();
//when avg drops back down, register the sigh
if(average <= 15) {
mySerial.println(8, DEC);
Serial.println("sigh detected. mobile unit");
digitalWrite(sighPin, HIGH);
delay(1000);
digitalWrite(sighPin, LOW);
possibleSigh=false;
}
}
else
possibleSigh=false;
}
///////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////
void serialHandler()
{
if (mySerial.available()) {
Serial.print((char)mySerial.read());
}
if (Serial.available()) {
mySerial.print((char)Serial.read());
}
delay(100);
}