Diff: sampler.cpp

Revision:

62:8e2fbe131b53

Parent:

61:1de72bdab0ef

--- a/sampler.cpp	Sun May 17 00:27:16 2015 +0000
+++ b/sampler.cpp	Sun Jun 28 03:06:00 2015 +0000
@@ -1,19 +1,22 @@
 #include "mbed.h"
-
+#include <qrsdet.h>
 // Use a ticker (interrupt routine) to sample the ADC at a fast rate (is 200Khz the max?), and generate an average value
 // Use another ticker to grab the average value at 1Khz, which is the maximum useful sampling rate for HRV data collection
 
 
 // These need to divide evenly into each other
-#define SAMPLING_RATE_HZ 4000   
-#define READ_OUT_RATE_HZ 50  
 
-#define SAMPLES_PER_READOUT (SAMPLING_RATE_HZ/READ_OUT_RATE_HZ)
+// 3 means sample at 8x read-out rate - SAMPLE_RATE is defined in qrsdet.h
+#define SHIFT_FOR_READ_OUT 1
+#define ADC_RATE (SAMPLE_RATE<<SHIFT_FOR_READ_OUT)  
+#define READ_OUT_RATE_HZ SAMPLE_RATE 
+
+#define SAMPLES_PER_READOUT (1<<SHIFT_FOR_READ_OUT)
 
 AnalogIn ECG(P0_1);  
 Ticker sampling_rate;
 int NumReadings=0;
-uint32_t ReadingTotal=0;
+int32_t ReadingTotal=0;
 void (*SamplingFunction)(uint32_t);
 
 
@@ -23,7 +26,7 @@
     ReadingTotal += ECG.read_u16();    
     if (NumReadings == SAMPLES_PER_READOUT) 
     {
-        SamplingFunction(ReadingTotal/NumReadings);
+        SamplingFunction(ReadingTotal>>SHIFT_FOR_READ_OUT); 
         ReadingTotal = 0;
         NumReadings = 0;
     }                                                                                                 
@@ -32,5 +35,5 @@
 void setup_sampler(void (*function)(uint32_t)) 
 {
     SamplingFunction = function;
-    sampling_rate.attach(&ADC_read, 1.0/SAMPLING_RATE_HZ);
+    sampling_rate.attach(&ADC_read, 1.0/ADC_RATE);
 }