Diff: main.cpp

Revision:

4:d4804771134a

Parent:

3:c80aa39db5bb

Child:

5:44cfc3e81d1c

--- a/main.cpp	Thu Jan 25 09:21:43 2018 +0000
+++ b/main.cpp	Thu Jan 25 10:20:46 2018 +0000
@@ -6,6 +6,15 @@
 
 #define N_SAMPLES 1024
 
+#define PEAK_SEARCH_START 1 //first bin to include in peak search
+#define PEAK_SEARCH_END 50 //last bin to include in peak search
+#define SUM_AROUND_PEAK 1 //+/- this many bins
+
+#define REGRESSION_SLOPE 53.77986f //from Excel fit to test data
+#define REGRESSION_INTERCEPT -80.07f
+
+float thresholds[] = {10.f, 30.f, 50.f, 70.f}; //estimated t90 thresholds to turn on LEDs
+
 //mbed class def
 Serial pc(USBTX, USBRX); // tx, rx
 MS5607SPI pressure_sensor(p5, p6, p7, p8); // mosi, miso, sclk, cs
@@ -52,6 +61,8 @@
     int iter_counter = 0; //Iteration counter
     iter_timer.start();
 
+    printf("fsmpl titer mean_press fmax sum_peak    t90\n");
+
     //program loop    
     while(1) {
         sample_timer.reset();
@@ -83,31 +94,48 @@
         mag_data[0] = f_data[0];
         mag_data[N_SAMPLES / 2] = f_data[1];
         
-        //Output iteration data
-        iter_counter++;
-        printf("%10.5g %5d %5d\n", f_data[0] / N_SAMPLES, 1000000 / (sample_timer.read_us() / N_SAMPLES), iter_timer.read_ms() / iter_counter);
-        
         //Output raw data
         /*for(int i = 0; i < N_SAMPLES; i++) {
             printf("%f %f\n", p_data_raw[i], f_data[i]);
         }*/
         
-        //Analysis - average from bin 15 to bin 25
-        //Print out subset of data
-        float average = 0;
         
-        for(int i = 15; i < 25; i++) {
-            printf("%10.5g ", mag_data[i]);
-            average += mag_data[i] / 10;
+        //Find peak in spectrum
+        float max_mag = -1;
+        int max_mag_i = -1;
+        for(int i = PEAK_SEARCH_START + SUM_AROUND_PEAK; i < PEAK_SEARCH_END; i++){
+            //printf("%10f ", mag_data[i]);
+            if(mag_data[i] > max_mag) {
+                max_mag_i = i;
+                max_mag = mag_data[i];
+            }
+        }
+        //printf("\n");
+        
+        //Sum surrounding
+        float sum = 0.f;
+        for(int i = max_mag_i - SUM_AROUND_PEAK; i < (max_mag_i + SUM_AROUND_PEAK + 1); i++) {
+            sum += mag_data[i];
+            //printf("%10f ", mag_data[i]);
         }
         
-        printf("%10.5g\n", average);
+        //printf("\n");
+        
+        //Scale by N_SAMPLES to recover pressure in Pa
+        sum /= N_SAMPLES;
+        
+        //Apply inverse of logarithmic regression from test data
+        float t90 = exp((sum + 80.07) / 53.77986);
+        
+        
+        //Output iteration data
+        iter_counter++;
+        printf("%5d %5d %10.0f %4d %10.5e %3.0f\n", 1000000 / (sample_timer.read_us() / N_SAMPLES), iter_timer.read_ms() / iter_counter, f_data[0] / N_SAMPLES, max_mag_i, sum, t90);
         
         //Set LEDs based on thresholds
-        leds[0] = average > 1000.f;
-        leds[1] = average > 2000.f;
-        leds[2] = average > 3000.f;
-        leds[3] = average > 4000.f;
+        for(int i = 0; i < 4; i++) {
+            leds[i] = t90 >= thresholds[i];
+        }
         
         //break;
     }