Revision 0:eefa433e1005, committed 2018-05-26

Comitter:

moe414

Date:

Sat May 26 03:59:57 2018 +0000

Commit message:

Respiration sensor using a Thermistor

Changed in this revision

diff -r 000000000000 -r eefa433e1005 main.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sat May 26 03:59:57 2018 +0000
@@ -0,0 +1,45 @@
+/*
+Repiration rate using an NTC thermistor 
+this porgam is desgined to read the the voltage on the thrmistor sensor and convert it to temperature.
+A timer will start at the begining and after 60 seconds the program will print the breath per minute.
+the program will set the first tempeature as the threshold and compare it with the threshold if the 
+temperature increased by 0.5 degrees a count will increase each time it occures. when the program reaches 
+60 seconds, the program will print the number of counts which relates to the breathing rate per minute.
+created by Mohammed Al Qanber on APR 10, 2018.
+*/
+#include "mbed.h"
+#include "therm.h"// the temperature eqiuation written in a function in a seperate file.
+AnalogIn sensor(A0);//attache AnalogIn to pin A0.
+ Serial pc(USBTX, USBRX);// serial communications.
+ //varibales definition 
+float tempinf(float sensor) ;
+float TT;
+float tempin;
+Timer mytimer; // create the timer function. 
+ int count =0; // initial the count with zero value.
+int main(){
+    while(1){
+       
+        float reading = sensor; //set the voltage reading from the function to a variable.
+        //pc.printf("the reading value is %f\n",reading);//print the analog reading voltage
+float threshold=tempinf(sensor); //set the first temperature as the threshold.
+  mytimer.start(); //start the timer.
+   // pc.printf("the reading value is %f\n",threshold);// print the threshold value if needed.
+  tempin=tempinf(sensor);//use the temprature equation output and assgin it to tempin
+//pc.printf(" %f C \n",tempin);//print the temperature value if needed.
+   wait(1.5);  // wait 1.5 seconds between readings.  
+   //the if function will compare the temperature reading to the threshold.   
+if (tempin>threshold+1/2){
+ count++; // the count will increase by one when the if statment is true.
+}
+ int timer=mytimer.read(); // this function will read the timer value.
+ // if the timer value reaches 60 seconds the if statment will be true.
+ if (timer>=60){
+   // pc.printf(" time: %d  \n",timer); // print the time to make sure it reached 60 seconds if needed.
+    pc.printf(" %d  \n",count); // print the breath per minute.
+    mytimer.reset();// reset the timer for the next cycle 
+    count =0;// reset the counter for the next cycle.
+    } 
+}
+}
+ 

diff -r 000000000000 -r eefa433e1005 therm.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/therm.h	Sat May 26 03:59:57 2018 +0000
@@ -0,0 +1,12 @@
+
+//this function is programmed to take the analong voltage value and convert it to temperature.
+float tempinf(float sensor) {
+        // first it will convert the voltage to resistance
+        double R_ratio = (1/sensor- 1);
+        double logR_ratio=log(R_ratio);
+        //the next line will convert the resistance to temperatue in Kelvin units using Steinhart and Hart equation.
+        double T_kelvin=1/(.003354016+.000256985*logR_ratio+.000002620131*logR_ratio*logR_ratio);
+        float T = (T_kelvin - 273);//conver the temperture to celsious 
+        return T; // returen the temperature value.
+
+}
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