Robert Hill
This is the Heart Rate demo program, testing and verifying the functionality of the HR sensor.
Diff: HeartRate.cpp
- Revision:
- 0:92d3ea9d3e67
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/HeartRate.cpp Wed Feb 24 17:43:56 2016 +0000
@@ -0,0 +1,202 @@
+#include "PulseSensor.h"
+#include "mbed.h"
+//#include "AnalogIn.h"
+
+DigitalOut led_red(LED_RED);
+DigitalOut led_green(LED_GREEN);
+DigitalOut led_blue(LED_BLUE);
+DigitalIn sw2(SW2);
+DigitalIn sw3(SW3);
+Serial pc(USBTX, USBRX);
+
+AnalogIn Pulse_Signal(A0); //Initialize analog input for pulse signal
+
+bool Button_Pressed = true; //Initialize flag for output on terminal
+
+PulseSensor::PulseSensor(PinName analogPin, void (*printDataCallback)(char,int), int callbackRateMs)
+{
+ _started = false;
+
+ _pAin = new AnalogIn(analogPin);
+
+ _callbackRateMs = callbackRateMs;
+
+ _printDataCallback = printDataCallback;
+}
+
+
+PulseSensor::~PulseSensor()
+{
+ delete _pAin;
+}
+
+
+void PulseSensor::process_data_ticker_callback(void)
+{
+ _printDataCallback('S', Signal); // send Processing the raw Pulse Sensor data
+ if (QS == true) { // Quantified Self flag is true when a heartbeat is found
+ //fadeRate = 255; // Set 'fadeRate' Variable to 255 to fade LED with pulse
+ _printDataCallback('B',BPM); // send heart rate with a 'B' prefix
+ _printDataCallback('Q',IBI); // send time between beats with a 'Q' prefix
+ QS = false; // reset the Quantified Self flag for next time
+ }
+}
+
+
+void PulseSensor::sensor_ticker_callback(void)
+{
+ Signal = 1023 * _pAin->read(); // 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 by waiting
+ //this also sets limit to HR sensor to max =240 BPMs
+ 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
+ long 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
+ 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
+ }
+}
+
+void sendDataToProcessing(char symbol, int data)
+{
+ pc.printf("%c%d\r\n", symbol, data);
+}
+
+int main()
+{
+ pc.baud(9600);
+ pc.printf("Hello World from FRDM-K64F board. This is the Heart Rate Demo Program. ");
+ pc.printf("Press SW2 (Button Near FRDM Logo) to see current Heart Rate.\n ");
+
+ led_blue = 1; //LED is off
+ led_green = 1;
+ led_red = 1;
+
+ PulseSensor Pulse_Signal(A0, sendDataToProcessing);
+ Pulse_Signal.start();
+ while(1)
+ {
+
+ if (sw2 == 0 && Button_Pressed == true)
+ {
+ Pulse_Signal.stop(); //stops the continuous signal
+ pc.printf("Current Heart Rate is: %d BPM \t", Pulse_Signal.BPM);
+ Button_Pressed= false;
+
+
+ wait(1);
+ }
+ else if (sw3 == 0 && Button_Pressed == true)
+ {
+ Pulse_Signal.start(); //restarts the pulse signal
+ // Button_Pressed= false;
+ }
+ Button_Pressed = true;
+ }
+}
+
+bool PulseSensor::start()
+{
+ if (_started == false)
+ {
+ sampleCounter = 0;
+ lastBeatTime = 0;
+ P =512;
+ T = 512;
+ thresh = 512;
+ amp = 100;
+ firstBeat = true;
+ secondBeat = true;
+
+ BPM=0;
+ Signal=0;
+ IBI = 600;
+ Pulse = false;
+ QS = false;
+
+ _pulseSensorTicker.attach(this, &PulseSensor::sensor_ticker_callback, ((float)_sensorTickRateMs/1000));
+ _processDataTicker.attach(this, &PulseSensor::process_data_ticker_callback, ((float)_callbackRateMs/1000));
+ _started = true;
+ return true;
+ }
+ else
+ {
+ return false;
+ }
+}
+
+bool PulseSensor::stop()
+{
+ if(_started == true)
+ {
+ _pulseSensorTicker.detach();
+ _processDataTicker.detach();
+ _started = false;
+ return true;
+ }
+ else
+ {
+ return false;
+ }
+}
\ No newline at end of file
