Diff: main.cpp

Revision:

0:e3c27b347c15

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Tue Mar 12 13:19:29 2013 +0000
@@ -0,0 +1,55 @@
+/*
+ * here is an example for using the GP2d12 sensor.
+ * Basically I interpolated the output curve (output voltage wrt distance) whose
+ * Matlab code is reported below.
+ * I'm too lazy for creating a class, so the code has been provided within the 
+ * main function
+ */
+#include "mbed.h"
+
+DigitalOut myled(LED1);
+
+AnalogIn s (p20);
+
+#define k_5 12466.0
+#define k_4 -23216.0
+#define k_3 14974.0
+#define k_2 -3585.0
+#define k_1 19.0
+#define k_0 96.0
+
+int main() {
+    while(1) {
+        float val = s.read();
+        float res = 0.0;
+        res += k_5*(val*val*val*val*val);
+        res += k_4*(val*val*val*val);
+        res += k_3*(val*val*val);
+        res += k_2*(val*val);
+        res += k_1*val;
+        res += k_0;
+        printf("%f, dst=%f\n\r", val, res);
+        myled = 1;
+        wait(0.2);
+        myled = 0;
+        wait(0.2);
+    }
+}
+
+/*
+Matlab commands:
+Y = [10    15    20    25    30    35    40    50    60    70    80   90    100];
+X = [0.70  0.57  0.39  0.32  0.28  0.24  0.20  0.17  0.13  0.12  0.1  0.01  0.0001];
+p = polyfit(X, Y, 5);
+x_test = [0:0.05:0.7];
+for i=1:length(x_test)
+    y_test(i) = polyval(p, x_test(i));
+end
+polyval(p,0.5)
+%x = 0.5;
+%res = p(1)*(x^4) + p(2)*(x^3) + p(3)*(x^2) + p(4)*(x^1) + p(5)*(x^0);
+figure
+plot(X, Y, 'b')
+hold on
+plot(x_test, y_test, 'r')
+*/