main.cpp

00001 #include "mbed.h"
00002 
00003 
00004 //Global objects
00005 DigitalOut myled(LED1);
00006 Serial pc(USBTX, USBRX);
00007 Ticker t;
00008 
00009 //Integer state of the LED
00010 //static makes it visible only within main.cpp
00011 static int state = 0;
00012 
00013 //Function prototype
00014 void doISR();
00015 
00016 int main() {
00017    
00018    //Initialise
00019    pc.baud(115200);
00020    t.attach(&doISR, 2);
00021    myled = 0;
00022     
00023     //Main loop
00024     while(1) {
00025         
00026         //Go to sleep and wait for an ISR to wake
00027         sleep();    //At is says
00028         
00029         //At this point, the ISR has run
00030         
00031         //Update LED
00032         myled = state;
00033         
00034         //Echo to terminal
00035         if (state == 0) {
00036             pc.printf("LED OFF\n");
00037         } else {
00038             pc.printf("LED ON\n");   
00039         }
00040     }
00041 }
00042 
00043 //Note - the ISR is short, and does NOT call functions
00044 //such as printf (it's actually unsafe to do so)
00045 //Always check a function is "reentrant" before calling it
00046 void doISR() {
00047     //Toggle 0 to 1, or 1 to 0
00048     state ^= 1;      
00049 }