PulseSensor.h

00001 #ifndef PULSE_SENSOR_H
00002 #define PULSE_SENSOR_H
00003 
00004 #include "mbed.h"
00005 
00006 
00007 /**
00008  * Class for interfacing with a http://pulsesensor.myshopify.com/ 'Pulse Sensor Amped'.
00009  * The contents of this class are based on the "Pulse Sensor Amped 1.1" Arduino Sketch.
00010  *
00011  * When using this class for the first time, it is recommended that you use the Processing 
00012  * GUI app available http://pulsesensor.myshopify.com/pages/code-and-guide. Using this, you
00013  * will easily be able to verify the operating of your sensor, and the integration of this
00014  * class into your mbed project. 
00015  */
00016  
00017 class PulseSensor
00018 {
00019     private:
00020         volatile int rate[10];                    // used to hold last ten IBI values
00021         volatile unsigned long sampleCounter;          // used to determine pulse timing
00022         volatile unsigned long lastBeatTime;           // used to find the inter beat interval
00023         volatile int P;                      // used to find peak in pulse wave
00024         volatile int T;                     // used to find trough in pulse wave
00025         volatile int thresh;                // used to find instant moment of heart beat
00026         volatile int amp;                   // used to hold amplitude of pulse waveform
00027         volatile bool firstBeat;        // used to seed rate array so we startup with reasonable BPM
00028         volatile bool secondBeat;       // used to seed rate array so we startup with reasonable BPM
00029         
00030         // these variables are volatile because they are used during the interrupt service routine!
00031         volatile uint8_t BPM;                   // used to hold the pulse rate
00032         volatile int Signal;                // holds the incoming raw data
00033         volatile int IBI;             // holds the time between beats, the Inter-Beat Interval
00034         volatile bool Pulse;        // true when pulse wave is high, false when it's low
00035         volatile bool QS;           // becomes true when a beat is found
00036     
00037     
00038         void (*_printDataCallback)(int);
00039         static const int _sensorTickRateMs = 2;
00040         int       _callbackRateMs;
00041         bool      _started;
00042         
00043         AnalogIn *_pAin;
00044         Ticker    _pulseSensorTicker;
00045         Ticker    _processDataTicker;
00046         
00047         void sensor_ticker_callback(void);
00048         void process_data_ticker_callback(void);
00049     
00050     public:
00051         /** PulseSensor Constructor - Note this does not start the reading of the sensor.
00052          * @param   analogPin Name of the analog pin that the sensor is connected to.
00053          * @param   printDataCallback Pointer to function which will be called to print the latest data. Output format available here: http://pulsesensor.myshopify.com/pages/code-and-guide
00054          * @param   callbackRateMs Rate at which the printDataCallback is to be called, recommended is 20ms for graphing of pulse signal.
00055          */
00056         //volatile uint8_t BPM;
00057         
00058         PulseSensor(PinName analogPin, void (*printDataCallback)(int), int callbackRateMs=20);
00059         
00060         /** Destructor */
00061         ~PulseSensor();
00062         
00063         /** Start reading the Pulse Sensor, and sending current readings to the print data callback.
00064          * @returns true if reading of the sensor is started, false if reading was aleady in progress.
00065          */
00066         bool start();
00067         
00068         /** Stops the current reading of the Pulse Senson.
00069          * @return true if reading is stopped, false if reading was already stopped.
00070          */
00071         bool stop();
00072         
00073         uint8_t get_bpm();
00074 };
00075 
00076 #endif