main.cpp

00001 /*
00002  * Simple monophonic synthesizer
00003  * auther: alaif.
00004  */
00005 #include "mbed.h"
00006 #include "USBMIDI.h"
00007 
00008 /* MIDI note no -> FREQ */
00009 #include "math.h"
00010 #define NOTE2FREQ(note) (440 * pow(2, ((note - 69) / 12.0f)))
00011 
00012 /* HARDWARE Config */
00013 PwmOut sp1(p21);
00014 DigitalOut led_ready(LED1);
00015 DigitalOut led_noteon(LED2);
00016 
00017 //NOTE ON event
00018 void note_on(int note, int vel)
00019 {
00020     if (vel != 0) {
00021         sp1.period(1.0f / NOTE2FREQ(note));         //Set freq
00022         sp1.write(0.5f);                            //SQUARE WAVE ON
00023         led_noteon = 1;
00024     } else {
00025         sp1.write(0.0f);                            //SQUARE WAVE OFF
00026         led_noteon = 0;
00027     }
00028 }
00029 
00030 //NOTE OFF event
00031 void note_off()
00032 {
00033     sp1.write(0.0f);
00034     led_noteon = 0;
00035 }
00036 
00037 //Recv midi message handler.
00038 void do_message(MIDIMessage msg)
00039 {
00040     int key = msg.key();
00041     switch (msg.type()) {
00042         case MIDIMessage::NoteOnType:
00043             note_on(key, msg.velocity());
00044             break;
00045         case MIDIMessage::NoteOffType:
00046             note_off();
00047             break;
00048     }
00049 }
00050 
00051 /* Main */
00052 USBMIDI midi;
00053 int main() {
00054     led_ready = 0;          
00055     midi.attach(do_message);    // call back for messages received    
00056     led_ready = 1;
00057     
00058     while (1) {}
00059 }