PulseRate.h

00001 /**
00002  *  @file       PulseRate.h
00003  *  @brief      Header file for PulseRate.cpp
00004  *  @date       2014.08.08
00005  *  @version    1.0.0
00006  */
00007 #ifndef _INC_PulseRate
00008 #define _INC_PulseRate
00009 
00010 #include "mbed.h"
00011 
00012 #define LED_ON  (0)
00013 #define LED_OFF (1)
00014 
00015 #define BEEP_FREQ (1000.0)
00016 #define BEEP_LOUD (0.5)
00017 
00018 #define SAMPLING_RATE (0.01)    /* A/D sampling rate (10ms) */
00019 #define SPL_NUM (100)           /* Range of sampling number (0 - 99) */
00020 
00021 #define AD_OFFSET (21845)       /* Offset value for VREF (about +1.1V) */
00022 
00023 #define COEF_BH (0x3FCCB062)    /* High pass filter b0, -b1 coefficient 0.1Hz/100Hz Q30 format */
00024                                 /* Use (0x3F02946A) when 0.5Hz/100Hz Q30 format */
00025 #define COEF_AH (0x3F9960C5)    /* High pass filter -a1     coefficient 0.1Hz/200Hz Q30 format */
00026                                 /* Use (0x3E0528D5) when 0.5Hz/100Hz Q30 format */
00027 
00028 #define MV_LENGTH (5)           /* Number of moving averaging for pulse detection */
00029 #define TH_COEF (0.993)         /* Coefficient for pulse threshold (exponential decline) */
00030 #define PEAK_MIN (127)          /* Ignore waveform as pulse under this value */
00031 
00032 #define PR_LENGTH (5)           /* Number of average for pulse rate */
00033 #define PR_1MIN_SPL (6000)      /* Number of sampling for 1 minute (60*100) */
00034 #define PR_INT_MAX (300)        /* 20 bpm (60*100/20) */
00035 #define PR_INT_MIN (20)         /* 300 bpm (60*100/300) */
00036 
00037 /** Calculate pulse waveform and pulse rate
00038  */
00039 class PulseRate {
00040 
00041 public:
00042     PulseRate(PinName sensor, PinName sync_led, PinName beep);
00043     void start_sampling();
00044     bool get_wave(uint32_t &num, int32_t &wave_val);
00045     bool get_pr_val(uint32_t &pr);
00046 
00047 private:
00048     Ticker      _sampling;          /* Interval timer for data sampling */
00049 
00050     AnalogIn    _sensor;            /* A/D converter */
00051     DigitalOut  _sync_led;          /* Synchronous LED */
00052     PwmOut      _beep;              /* Piezo sounder */
00053 
00054     /* Pulse waveform */
00055     int32_t     _val;               /* Pulse waveform value */
00056     int32_t     _prev_val;          /* Previous value */
00057     int32_t     _reg_hpf;           /* High pass filter memory value */
00058     bool        _wave_flag;         /* Pulse waveform set flag */
00059     
00060     uint32_t    _sampling_num;      /* Sampling number */
00061     
00062     /* Moving averaging */
00063     int32_t     _mv_buf[MV_LENGTH]; /* Circular buffer */
00064     int32_t     _mv_idx;            /* Buffer index */
00065     
00066     /* Threshold for detecting pulse */
00067     int32_t     _detect_val;        /* Detection value */
00068     int32_t     _prev_dt_val;       /* Previous data */
00069     
00070     int32_t     _threshold_val;     /* Threshold value */
00071     int32_t     _prev_th_val;       /* Previous data */
00072     
00073     /* Pulse rate */
00074     int32_t     _pr_counter;        /* Counter for pulse rate */
00075     int32_t     _pr_buf[PR_LENGTH]; /* Circular buffer */
00076     int32_t     _pr_idx;            /* Buffer index */
00077     
00078     int32_t     _pr;                /* Pulse rate value */
00079     bool        _pr_flag;           /* Pulse rate set flag */
00080 
00081     /* Member functions */
00082     void interval_timer();
00083     int32_t hpf(int32_t val);
00084     bool detect_peak(int32_t val);
00085     void calc_pr();
00086 };
00087 #endif    /* INC_PulseRate */