main.cpp

00001 /* Power electronics usalle*/
00002 
00003 #include "mbed.h"
00004 
00005 
00006 #ifndef M_PI 
00007 #define M_PI 3.14159265358979323846 
00008 #endif 
00009 
00010 // Number of samples to generate sine pattern
00011 #define SINE_STEPS        100
00012 // Pwm period in us
00013 #define PWM_PERIOD        20  
00014 
00015 
00016 DigitalOut myled(LED1); 
00017 PwmOut CH1(PWM_OUT); 
00018 
00019 
00020 
00021 // dc : duty cycle
00022 // n:   a sample 
00023 // T:   Time in microsecond the sine_dc function is evaluated
00024 // 1/PWM_PERIOD defines the conmutation frequency (default 50kHz)
00025 // T divided by  PWM_PERIOD defines the number of pwm cycles for each sine term sample (default 8.3)
00026 // T times SINE_STEPS defines sine modulation period
00027  
00028  /* This program calculates values of a sine 
00029  function and splits them up in 100 points, these points are then written
00030   to the duty cycle of the pwm signals.
00031 */
00032 Ticker interrupt;
00033 InterruptIn button(USER_BUTTON);
00034 int n;
00035 double dc_min = 0.0, dc_max = 1.0;
00036 void sine_dc() { 
00037     double dc, sine_term; 
00038     n = n + 1;
00039     if(n == SINE_STEPS) n = 0;
00040     sine_term = sin(2*M_PI*n/SINE_STEPS);
00041     // Convert sine term to duty cycle: if sine_term == 0, then dc = 0.5
00042     if (sine_term > 0) dc = 0.5 + (sine_term * (dc_max - 0.5));
00043     if (sine_term < 0) dc = 0.5 + (sine_term * (0.5 - dc_min));
00044     if (sine_term == 0) dc = 0.5;
00045     CH1.write(dc);
00046 }
00047 
00048 int main() {
00049     int T = 166;
00050     n = 0;
00051     CH1.period_us(PWM_PERIOD);
00052     CH1.write(0.5);
00053 
00054 
00055     
00056     //
00057     interrupt.attach_us(&sine_dc, T);
00058     
00059     while(1) {
00060          myled = !myled;
00061          wait(1);
00062     }
00063 }
00064