sampler.cpp

00001 #include "mbed.h"
00002 #include <qrsdet.h>
00003 // Use a ticker (interrupt routine) to sample the ADC at a fast rate (is 200Khz the max?), and generate an average value
00004 // Use another ticker to grab the average value at 1Khz, which is the maximum useful sampling rate for HRV data collection
00005 
00006 
00007 // These need to divide evenly into each other
00008 
00009 // 3 means sample at 8x read-out rate - SAMPLE_RATE is defined in qrsdet.h
00010 #define SHIFT_FOR_READ_OUT 1
00011 #define ADC_RATE (SAMPLE_RATE<<SHIFT_FOR_READ_OUT)  
00012 #define READ_OUT_RATE_HZ SAMPLE_RATE 
00013 
00014 #define SAMPLES_PER_READOUT (1<<SHIFT_FOR_READ_OUT)
00015 
00016 AnalogIn ECG(P0_1);  
00017 Ticker sampling_rate;
00018 int NumReadings=0;
00019 int32_t ReadingTotal=0;
00020 void (*SamplingFunction)(uint32_t);
00021 
00022 
00023 void ADC_read()
00024 {    
00025     NumReadings++;
00026     ReadingTotal += ECG.read_u16();    
00027     if (NumReadings == SAMPLES_PER_READOUT) 
00028     {
00029         SamplingFunction(ReadingTotal>>SHIFT_FOR_READ_OUT); 
00030         ReadingTotal = 0;
00031         NumReadings = 0;
00032     }                                                                                                 
00033 }
00034 
00035 void setup_sampler(void (*function)(uint32_t)) 
00036 {
00037     SamplingFunction = function;
00038     sampling_rate.attach(&ADC_read, 1.0/ADC_RATE);
00039 }