1. Example 15 Interrupt-Driven Controller
Lecture L6.2

3. Connecting an LED to a Port P pin

4. // Example 15a Traffic Lights
#include <hidef.h> /* common defines and macros */
#include <mc9s12dp256.h> /* derivative information */
#include "main_asm.h" /* interface to the assembly module */
#pragma LINK_INFO DERIVATIVE "mc9s12dp256b"
int dtime; // delay time
int ix; // index into states
const int numstates = 6;
const char PortH[] = { // --RYGRYG
0x0C, //
0x14, //
0x24, //
0x21, //
0x22, //
0x24, // };
const int delay[] = {
488, // 5 sec delay
98, // 1 sec delay
98, // 1 sec delay
488, // 5 sec delay

5. void interrupt 7 handler(){
dtime--;
if(dtime == 0){
PTH = PortH[ix]; // turn on next lights
dtime = delay[ix]; // get next delay time
ix++; // increment index
if(ix == numstates){ // after going through all states
ix = 0; // reset index to 0 }
clear_RTI_flag();

6. void main(void) {
PLL_init(); // set system clock frequency to 24 MHz
DDRH = 0xFF; // all bits of Port H are outputs
RTI_init(); // initialize RTI to ms interrupts
ix = 0; // reset index into states
dtime = 1; // start traffic light right away
while(1) { // do nothing while traffic light goes }

7. Interrupt-Driven Blinking SOS
International Morse Code

8. // Example 15b: Interrupt-Driven Controller: SOS
#include <hidef.h> /* common defines and macros */
#include <mc9s12dp256.h> /* derivative information */
#include "main_asm.h" /* interface to the assembly module */
#pragma LINK_INFO DERIVATIVE "mc9s12dp256b"
unsigned short dtime; // delay time
int ix; // index into states
const int numstates = 18;
const char seg7[] = {
0x6D, 0x00, 0x6D, 0x00, 0x6D, 0x00, // S
0x3F, 0x00, 0x3F, 0x00, 0x3F, 0x00, // O };
const char delay[] = {
0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x18, // dots
0x24, 0x24, 0x24, 0x24, 0x24, 0x24, // dashes
0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x30, // dots

9. void interrupt 7 handler(){
dtime--;
if(dtime == 0){
seg7_on(seg7[ix]); // turn on next display
dtime = delay[ix]; // get next delay time
ix++; // increment index
if(ix == numstates){ // after going through all states
ix = 0; // reset index to 0 }
clear_RTI_flag();

10. void main(void) {
PLL_init(); // set system clock frequency to 24 MHz
seg7_enable();
RTI_init();
ix = 0; // reset index into states
dtime = 1; // start display right away
while(1) { // do nothing while display goes }