main.cpp

00001 //Theremin style demo using HC-SR04 Sonar and a speaker
00002 // moving a hand away/towards sonar changes audio frequency
00003 #include "mbed.h"
00004 #include "ultrasonic.h"
00005  
00006 DigitalOut audio(p26); //output to speaker amp or audio jack
00007 DigitalOut led(LED1); 
00008 DigitalOut led2(LED2);
00009  
00010 Timeout cycle;
00011  
00012 volatile int half_cycle_time = 1;
00013  
00014 //two calls to this interrupt routine generates a square wave
00015 void toggle_interrupt()
00016 {
00017     if (half_cycle_time>22000) audio=0; //mute if nothing in range
00018     else audio = !audio; //toggle to make half a square wave
00019     led = !led;
00020     cycle.detach();
00021     //update time for interrupt activation -change frequency of square wave
00022     cycle.attach_us(&toggle_interrupt, half_cycle_time);
00023 }
00024 void newdist(int distance)
00025 {
00026     //update frequency based on new sonar data
00027     led2 = !led2;
00028     half_cycle_time = distance<<3;
00029 }
00030 //HC-SR04 Sonar module
00031 ultrasonic mu(p6, p7, .07, 1, &newdist);    
00032 //Set the trigger pin to p6 and the echo pin to p7
00033 //have updates every .07 seconds and a timeout after 1
00034 //second, and call newdist when the distance changes
00035  
00036 int main()
00037 {
00038     audio = 0;
00039     led = 0;
00040     cycle.attach(&toggle_interrupt, half_cycle_time);
00041     mu.startUpdates();//start measuring the distance with the sonar
00042     while(1) {
00043         //Do something else here
00044         mu.checkDistance();     
00045         //call checkDistance() as much as possible, as this is where
00046         //the class checks if dist needs to be called.
00047     }
00048 }