main.cpp

00001 #include "mbed.h"
00002 
00003 #define PI 3.142
00004 #define AMP 0.8
00005 
00006 #define SIGNAL_OUTPUT_FREQ 25//usec
00007 // coz twice zone of human audibility
00008 AnalogOut signal(p18);
00009 AnalogIn adin(p17);
00010 
00011 Ticker t_wave;
00012 
00013 float freq;
00014 
00015 float wave_value;
00016 void sawtoothWave(){
00017     wave_value+=freq*SIGNAL_OUTPUT_FREQ/1000000;
00018     if(wave_value > 1.0)
00019         wave_value = 0.0;
00020     float output = AMP*wave_value;
00021     signal = output;
00022 }
00023 
00024 float theata;
00025 void sinWave(){
00026     theata += 2*PI*SIGNAL_OUTPUT_FREQ*freq/1000000;
00027     if(theata > 2*PI)
00028         theata = 0.0; 
00029     float output = AMP*( sin(theata)+0.5 );
00030     signal = output;
00031 }
00032 
00033 int main() {
00034     wave_value = 0.0;
00035     freq = 1000;
00036     t_wave.attach_us(&sinWave , SIGNAL_OUTPUT_FREQ);
00037     while(1){
00038         freq = 5000*adin.read();
00039     } 
00040 }