Revision 0:a78b08608d76, committed 2014-01-11

Comitter:

asagin

Date:

Sat Jan 11 12:50:28 2014 +0000

Child:

1:171a73d84261

Commit message:

I cannnot understand interrupt.;

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Interrupt.cpp	Sat Jan 11 12:50:28 2014 +0000
@@ -0,0 +1,98 @@
+
+volatile int rate[10];                    // used to hold last ten IBI values
+volatile unsigned long sampleCounter = 0;          // used to determine pulse timing
+volatile unsigned long lastBeatTime = 0;           // used to find the inter beat interval
+volatile int P =512;                      // used to find peak in pulse wave
+volatile int T = 512;                     // used to find trough in pulse wave
+volatile int thresh = 512;                // used to find instant moment of heart beat
+volatile int amp = 100;                   // used to hold amplitude of pulse waveform
+volatile bool firstBeat = true;        // used to seed rate array so we startup with reasonable BPM
+volatile bool secondBeat = true;       // used to seed rate array so we startup with reasonable BPM
+
+
+void interruptSetup(){     
+  // Initializes Timer2 to throw an interrupt every 2mS.
+  TCCR2A = 0x02;     // DISABLE PWM ON DIGITAL PINS 3 AND 11, AND GO INTO CTC MODE
+  TCCR2B = 0x06;     // DON'T FORCE COMPARE, 256 PRESCALER 
+  OCR2A = 0X7C;      // SET THE TOP OF THE COUNT TO 124 FOR 500Hz SAMPLE RATE
+  TIMSK2 = 0x02;     // ENABLE INTERRUPT ON MATCH BETWEEN TIMER2 AND OCR2A
+  sei();             // MAKE SURE GLOBAL INTERRUPTS ARE ENABLED      
+} 
+
+
+// THIS IS THE TIMER 2 INTERRUPT SERVICE ROUTINE. 
+// Timer 2 makes sure that we take a reading every 2 miliseconds
+ISR(TIMER2_COMPA_vect){                         // triggered when Timer2 counts to 124
+    cli();                                      // disable interrupts while we do this
+    Signal = analogRead(pulsePin);              // read the Pulse Sensor 
+    sampleCounter += 2;                         // keep track of the time in mS with this variable
+    int N = sampleCounter - lastBeatTime;       // monitor the time since the last beat to avoid noise
+
+//  find the peak and trough of the pulse wave
+    if(Signal < thresh && N > (IBI/5)*3){       // avoid dichrotic noise by waiting 3/5 of last IBI
+        if (Signal < T){                        // T is the trough
+            T = Signal;                         // keep track of lowest point in pulse wave 
+         }
+       }
+      
+    if(Signal > thresh && Signal > P){          // thresh condition helps avoid noise
+        P = Signal;                             // P is the peak
+       }                                        // keep track of highest point in pulse wave
+    
+  //  NOW IT'S TIME TO LOOK FOR THE HEART BEAT
+  // signal surges up in value every time there is a pulse
+if (N > 250){                                   // avoid high frequency noise
+  if ( (Signal > thresh) && (Pulse == false) && (N > (IBI/5)*3) ){        
+    Pulse = true;                               // set the Pulse flag when we think there is a pulse
+    digitalWrite(blinkPin,HIGH);                // turn on pin 13 LED
+    IBI = sampleCounter - lastBeatTime;         // measure time between beats in mS
+    lastBeatTime = sampleCounter;               // keep track of time for next pulse
+         
+         if(firstBeat){                         // if it's the first time we found a beat, if firstBeat == TRUE
+             firstBeat = false;                 // clear firstBeat flag
+             return;                            // IBI value is unreliable so discard it
+            }   
+         if(secondBeat){                        // if this is the second beat, if secondBeat == TRUE
+            secondBeat = false;                 // clear secondBeat flag
+               for(int i=0; i<=9; i++){         // seed the running total to get a realisitic BPM at startup
+                    rate[i] = IBI;                      
+                    }
+            }
+          
+    // keep a running total of the last 10 IBI values
+    word runningTotal = 0;                   // clear the runningTotal variable    
+
+    for(int i=0; i<=8; i++){                // shift data in the rate array
+          rate[i] = rate[i+1];              // and drop the oldest IBI value 
+          runningTotal += rate[i];          // add up the 9 oldest IBI values
+        }
+        
+    rate[9] = IBI;                          // add the latest IBI to the rate array
+    runningTotal += rate[9];                // add the latest IBI to runningTotal
+    runningTotal /= 10;                     // average the last 10 IBI values 
+    BPM = 60000/runningTotal;               // how many beats can fit into a minute? that's BPM!
+    QS = true;                              // set Quantified Self flag 
+    // QS FLAG IS NOT CLEARED INSIDE THIS ISR
+    }                       
+}
+
+  if (Signal < thresh && Pulse == true){     // when the values are going down, the beat is over
+      digitalWrite(blinkPin,LOW);            // turn off pin 13 LED
+      Pulse = false;                         // reset the Pulse flag so we can do it again
+      amp = P - T;                           // get amplitude of the pulse wave
+      thresh = amp/2 + T;                    // set thresh at 50% of the amplitude
+      P = thresh;                            // reset these for next time
+      T = thresh;
+     }
+  
+  if (N > 2500){                             // if 2.5 seconds go by without a beat
+      thresh = 512;                          // set thresh default
+      P = 512;                               // set P default
+      T = 512;                               // set T default
+      lastBeatTime = sampleCounter;          // bring the lastBeatTime up to date        
+      firstBeat = true;                      // set these to avoid noise
+      secondBeat = true;                     // when we get the heartbeat back
+     }
+  
+  sei();                                     // enable interrupts when youre done!
+}// end isr
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sat Jan 11 12:50:28 2014 +0000
@@ -0,0 +1,102 @@
+#include "mbed.h"
+
+/*
+>> Pulse Sensor Amped 1.1 <<
+This code is for Pulse Sensor Amped by Joel Murphy and Yury Gitman
+    www.pulsesensor.com 
+    >>> Pulse Sensor purple wire goes to Analog Pin 0 <<<
+Pulse Sensor sample aquisition and processing happens in the background via Timer 2 interrupt. 2mS sample rate.
+PWM on pins 3 and 11 will not work when using this code, because we are using Timer 2!
+The following variables are automatically updated:
+Signal :    int that holds the analog signal data straight from the sensor. updated every 2mS.
+IBI  :      int that holds the time interval between beats. 2mS resolution.
+BPM  :      int that holds the heart rate value, derived every beat, from averaging previous 10 IBI values.
+QS  :       boolean that is made true whenever Pulse is found and BPM is updated. User must reset.
+Pulse :     boolean that is true when a heartbeat is sensed then false in time with pin13 LED going out.
+
+This code is designed with output serial data to Processing sketch "PulseSensorAmped_Processing-xx"
+The Processing sketch is a simple data visualizer. 
+All the work to find the heartbeat and determine the heartrate happens in the code below.
+Pin 13 LED will blink with heartbeat.
+If you want to use pin 13 for something else, adjust the interrupt handler
+It will also fade an LED on pin fadePin with every beat. Put an LED and series resistor from fadePin to GND.
+Check here for detailed code walkthrough:
+http://pulsesensor.myshopify.com/pages/pulse-sensor-amped-arduino-v1dot1
+
+Code Version 02 by Joel Murphy & Yury Gitman  Fall 2012
+This update changes the HRV variable name to IBI, which stands for Inter-Beat Interval, for clarity.
+Switched the interrupt to Timer2.  500Hz sample rate, 2mS resolution IBI value.
+Fade LED pin moved to pin 5 (use of Timer2 disables PWM on pins 3 & 11).
+Tidied up inefficiencies since the last version. 
+*/
+
+/*
+//  VARIABLES
+int pulsePin = 0;                 // Pulse Sensor purple wire connected to analog pin 0
+int blinkPin = 13;                // pin to blink led at each beat
+int fadePin = 5;                  // pin to do fancy classy fading blink at each beat
+int fadeRate = 0;                 // used to fade LED on with PWM on fadePin
+*/
+
+AnalogIn pulsePin(p15);  //This is signal input
+SPI blinkPin(p11,p12,p13); 
+PwmOut fadePin(p26); 
+int fadeRate = 0;
+
+// these variables are volatile because they are used during the interrupt service routine!
+volatile int BPM;                   // used to hold the pulse rate
+volatile int Signal;                // holds the incoming raw data
+volatile int IBI = 600;             // holds the time between beats, the Inter-Beat Interval
+//volatile boolean Pulse = false;     // true when pulse wave is high, false when it's low
+//volatile boolean QS = false;        // becomes true when Arduoino finds a beat.
+volatile bool Pulse = false;     // true when pulse wave is high, false when it's low
+volatile bool QS = false;        // becomes true when Arduoino finds a beat.
+/*
+void setup(){
+  pinMode(blinkPin,OUTPUT);         // pin that will blink to your heartbeat!
+  pinMode(fadePin,OUTPUT);          // pin that will fade to your heartbeat!
+  Serial.begin(115200);             // we agree to talk fast!
+  interruptSetup();                 // sets up to read Pulse Sensor signal every 2mS 
+   // UN-COMMENT THE NEXT LINE IF YOU ARE POWERING The Pulse Sensor AT LOW VOLTAGE, 
+   // AND APPLY THAT VOLTAGE TO THE A-REF PIN
+   //analogReference(EXTERNAL);   
+}
+*/
+
+void setup(){
+ // Serial.begin (115200);             // we agree to talk fast!
+ // interruptSetup();                 // sets up to read Pulse Sensor signal every 2mS 
+ Serial deta(p9,p10);             // we agree to talk fast!
+ interruptSetup();                 // sets up to read Pulse Sensor signal every 2mS   
+   
+   // UN-COMMENT THE NEXT LINE IF YOU ARE POWERING The Pulse Sensor AT LOW VOLTAGE, 
+   // AND APPLY THAT VOLTAGE TO THE A-REF PIN
+   //analogReference(EXTERNAL);   
+}
+
+void loop(){
+  sendDataToProcessing('S', Signal);     // send Processing the raw Pulse Sensor data
+  if (QS == true){                       // Quantified Self flag is true when arduino finds a heartbeat
+        fadeRate = 255;                  // Set 'fadeRate' Variable to 255 to fade LED with pulse
+        sendDataToProcessing('B',BPM);   // send heart rate with a 'B' prefix
+        sendDataToProcessing('Q',IBI);   // send time between beats with a 'Q' prefix
+        QS = false;                      // reset the Quantified Self flag for next time    
+     }
+  
+  ledFadeToBeat();
+  
+  delay(20);                             //  take a break
+}
+
+
+void ledFadeToBeat(){
+    fadeRate -= 15;                         //  set LED fade value
+    fadeRate = constrain(fadeRate,0,255);   //  keep LED fade value from going into negative numbers!
+    analogWrite(fadePin,fadeRate);          //  fade LED
+  }
+
+
+void sendDataToProcessing(char symbol, int data ){
+    Serial.print(symbol);                // symbol prefix tells Processing what type of data is coming
+    Serial.println(data);                // the data to send culminating in a carriage return
+  }
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Sat Jan 11 12:50:28 2014 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/a9913a65894f
\ No newline at end of file