main.cpp

00001 /* Program Example 14.4: Sawtooth waveform on DAC output. View on oscilloscope. Port 0.26 is used for DAC output, i.e. mbed Pin 18
00002                                                 */
00003 // function prototype                                              
00004 void delay(void);
00005 // variable declarations                                              
00006 int dac_value;             //the value to be output
00007 //define addresses of control registers, as pointers to volatile data 
00008 #define DACR (*(volatile unsigned long *)(0x4008C000))
00009 #define PINSEL1 (*(volatile unsigned long *)(0x4002C004))
00010 
00011 int main(){
00012   PINSEL1=0x00200000; //set bits 21-20 to 10 to enable analog out on P0.26
00013   while(1){
00014     for (dac_value=0;dac_value<1023;dac_value=dac_value+1){
00015       DACR=(dac_value<<6); 
00016       delay();
00017     }
00018   }
00019  }
00020 
00021 void delay(void){            //delay function.
00022     int j;                      //loop variable j
00023     for (j=0; j<1000000; j++) {
00024         j++;
00025         j--;                      //waste time
00026     }
00027 }
00028