main.cpp

00001 /* Program Example 14.3: Uses digital input and output using control registers, and flashes an LED. LEDS connect to mbed pins 25 and 26. Switch input to pin 9.
00002                                           */
00003 // function prototypes                                   
00004 void delay(void);
00005 //Define Digital I/O registers
00006 #define FIO0DIR0 (*( volatile unsigned char *)(0x2009C000))
00007 #define FIO0PIN0 (*( volatile unsigned char *)(0x2009C014))
00008 #define FIO2DIR0 (*(volatile unsigned char *)(0x2009C040)) 
00009 #define FIO2PIN0 (*(volatile unsigned char *)(0x2009C054))
00010 //some variables
00011 char a;
00012 char b;
00013 char i;
00014 
00015 int main() {
00016    FIO0DIR0=0x00;             // set all bits of port 0 byte 0 to input 
00017    FIO2DIR0=0xFF;             // set port 2 byte 0 to output
00018    while(1) {
00019      if (FIO0PIN0&0x01==1){   // bit test port 0 pin 0 (mbed pin 9)
00020        a=0x01;                // this reverses the order of LED flashing
00021        b=0x02;                // based on the switch position
00022      } 
00023      else {    
00024        a=0x02;
00025        b=0x01;
00026      }
00027      FIO2PIN0 |= a;        
00028      delay();
00029      FIO2PIN0 &= ~a;                    
00030      delay();
00031              
00032      for (i=1;i<=3;i++){
00033        FIO2PIN0 |= b;    
00034        delay();
00035        FIO2PIN0 &= ~b;             
00036        delay();
00037      }
00038    }                          //end while loop
00039 }
00040 
00041 void delay(void){            //delay function.
00042     int j;                      //loop variable j
00043     for (j=0; j<1000000; j++) {
00044         j++;
00045         j--;                      //waste time
00046     }
00047 }