main.cpp

00001 #include "mbed.h"
00002 #include <cmath>
00003 
00004 #define PERIOD 2000
00005 
00006 float analog_avg(AnalogIn ain, int samples);
00007 float exp_curve(float x, float a);
00008 void HSVtoRGB( float *r, float *g, float *b, float h, float s, float v );
00009 
00010 AnalogIn pot(p20);
00011 PwmOut red(p23);
00012 PwmOut green(p21);
00013 PwmOut blue(p22);
00014 PwmOut sync(p25);
00015 DigitalOut out1(p30);
00016 
00017 int main() {
00018     int period = PERIOD;
00019     float r, g, b;
00020     
00021     red.period_us(period);
00022     green.period_us(period);
00023     blue.period_us(period);
00024     sync.period_us(period);
00025     sync.pulsewidth_us(period/2);
00026     while (1) {
00027         /*float h = pot * 360.0f;
00028         HSVtoRGB(&r, &g, &b, h, 1, 0.1);
00029         red.pulsewidth_us(r * PERIOD);
00030         green.pulsewidth_us(g * PERIOD);
00031         blue.pulsewidth_us(b * PERIOD);*/
00032         
00033         for (float h = 0; h < 360; h += 0.1) {
00034             out1 = 1;
00035             out1 = 0;
00036             HSVtoRGB(&r, &g, &b, h, 1, exp_curve(analog_avg(pot,3), 4));
00037             
00038             red.pulsewidth_us(exp_curve(r,1.5) * PERIOD);
00039             green.pulsewidth_us(exp_curve(g,1.5) * PERIOD);
00040             blue.pulsewidth_us(exp_curve(b,1.5) * PERIOD);
00041             
00042             wait_us(1000);
00043         }
00044     }
00045 }
00046 
00047 float analog_avg(AnalogIn ain, int samples) {
00048     int sum = 0;
00049     
00050     for (int i = 0; i < samples; i++) {
00051         sum += ain.read_u16();
00052     }
00053     
00054     return (sum / samples) / ((float)0xFFFF);
00055 }    
00056     
00057 // returns a value between 0.0 and 1.0 for an input x of 0.0 to 1.0
00058 // a affects how "exponential" this curve will be
00059 float exp_curve(float x, float a) {
00060     return (exp(x*a)-1)/(exp(a) - 1);
00061 }
00062 
00063 
00064 void HSVtoRGB( float *r, float *g, float *b, float h, float s, float v )
00065 {
00066     int i;
00067     float f, p, q, t;
00068     if( s == 0 ) {
00069         // achromatic (grey)
00070         *r = *g = *b = v;
00071         return;
00072     }
00073     h /= 60;            // sector 0 to 5
00074     i = floor( h );
00075     f = h - i;          // factorial part of h
00076     p = v * ( 1 - s );
00077     q = v * ( 1 - s * f );
00078     t = v * ( 1 - s * ( 1 - f ) );
00079     switch( i ) {
00080         case 0:
00081             *r = v;
00082             *g = t;
00083             *b = p;
00084             break;
00085         case 1:
00086             *r = q;
00087             *g = v;
00088             *b = p;
00089             break;
00090         case 2:
00091             *r = p;
00092             *g = v;
00093             *b = t;
00094             break;
00095         case 3:
00096             *r = p;
00097             *g = q;
00098             *b = v;
00099             break;
00100         case 4:
00101             *r = t;
00102             *g = p;
00103             *b = v;
00104             break;
00105         default:        // case 5:
00106             *r = v;
00107             *g = p;
00108             *b = q;
00109             break;
00110     }
00111 }