Rob Toulson / Mbed 2 deprecated PE_14-04_DACSawtooth

by Rob Toulson and Tim Wilmshurst from textbook "Fast and Effective Embedded Systems Design: Applying the ARM mbed"

Dependencies:   mbed

main.cpp@0:ee400a44f6f3, 2013-06-16 (annotated)

Committer:
robt
Date:
Sun Jun 16 15:41:50 2013 +0000
Revision:
0:ee400a44f6f3
by Rob Toulson and Tim Wilmshurst from textbook "Fast and Effective Embedded Systems Design: Applying the ARM mbed"

Who changed what in which revision?

UserRevisionLine numberNew contents of line
robt 0:ee400a44f6f3 1 /* 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
robt 0:ee400a44f6f3 2 */
robt 0:ee400a44f6f3 3 // function prototype
robt 0:ee400a44f6f3 4 void delay(void);
robt 0:ee400a44f6f3 5 // variable declarations
robt 0:ee400a44f6f3 6 int dac_value; //the value to be output
robt 0:ee400a44f6f3 7 //define addresses of control registers, as pointers to volatile data
robt 0:ee400a44f6f3 8 #define DACR (*(volatile unsigned long *)(0x4008C000))
robt 0:ee400a44f6f3 9 #define PINSEL1 (*(volatile unsigned long *)(0x4002C004))
robt 0:ee400a44f6f3 10
robt 0:ee400a44f6f3 11 int main(){
robt 0:ee400a44f6f3 12 PINSEL1=0x00200000; //set bits 21-20 to 10 to enable analog out on P0.26
robt 0:ee400a44f6f3 13 while(1){
robt 0:ee400a44f6f3 14 for (dac_value=0;dac_value<1023;dac_value=dac_value+1){
robt 0:ee400a44f6f3 15 DACR=(dac_value<<6);
robt 0:ee400a44f6f3 16 delay();
robt 0:ee400a44f6f3 17 }
robt 0:ee400a44f6f3 18 }
robt 0:ee400a44f6f3 19 }
robt 0:ee400a44f6f3 20
robt 0:ee400a44f6f3 21 void delay(void){ //delay function.
robt 0:ee400a44f6f3 22 int j; //loop variable j
robt 0:ee400a44f6f3 23 for (j=0; j<1000000; j++) {
robt 0:ee400a44f6f3 24 j++;
robt 0:ee400a44f6f3 25 j--; //waste time
robt 0:ee400a44f6f3 26 }
robt 0:ee400a44f6f3 27 }
robt 0:ee400a44f6f3 28