main.cpp

00001 #include "mbed.h"
00002 
00003 /* Various states */
00004 typedef enum tState 
00005 { 
00006   STATE_A,
00007   STATE_B,
00008   STATE_C 
00009 } tState;
00010 
00011 /* Variables */
00012 tState       state;       /* Current state */
00013 char         trigger;     /* Bit set to indicate which button triggers */
00014 
00015 InterruptIn  button1(p5); /* interrupt for button 1 at pin 5 */
00016 InterruptIn  button2(p6); /* interrupt for button 1 at pin 6 */
00017 InterruptIn  button3(p7); /* interrupt for button 1 at pin 7 */
00018 BusOut       task(LED1, LED2, LED3, LED4);
00019 
00020 /* Interrupt handlers when buttons is pressed */
00021 void int_button1() {trigger |= 0x01;}  
00022 void int_button2() {trigger |= 0x02;}
00023 void int_button3() {trigger |= 0x04;}
00024 
00025 /* task to be executed during each state transition */
00026 void do_task(int n) {task = n; wait(2.0);}
00027 
00028 void sleep(void) {__WFI();} /* Power-saving sleeping mode */
00029 
00030 
00031 int main() 
00032 {
00033   /* Enable pull-down resistor for each button */
00034   button1.mode(PullDown);
00035   button2.mode(PullDown);
00036   button3.mode(PullDown);
00037   
00038   /* Assign ISR to each button */
00039   button1.rise(&int_button1);
00040   button2.rise(&int_button2);
00041   button3.rise(&int_button3);
00042   
00043   /* initial the state machine */
00044   state = STATE_A;
00045   do_task(STATE_A);
00046   
00047   while(1) 
00048   {
00049     /* While I am not triggered, sleep */
00050     while (!trigger)
00051       sleep();
00052     
00053     /* I am awake now. Check which button has triggered*/
00054     switch (state)
00055     {
00056       //////////////////////////////////////////////////////////////////
00057       case STATE_A:  ///////////////////////////////////////////////////
00058       //////////////////////////////////////////////////////////////////
00059         if (trigger & 0x01) /* Button 1 down */
00060         {
00061           do_task(1);
00062           state = STATE_B; /* Transit to STATE_B */
00063         }
00064         trigger = 0; /* Ignore other triggers in this state */
00065         break;
00066 
00067       //////////////////////////////////////////////////////////////////
00068       case STATE_B:  ///////////////////////////////////////////////////
00069       //////////////////////////////////////////////////////////////////
00070         if (trigger & 0x01) /* Button 1 down */
00071         {
00072           do_task(2);
00073           state = STATE_A;
00074         }
00075         if (trigger & 0x02) /* Button 2 down */
00076         {
00077           do_task(3);
00078           /* Remain in the same state */
00079         }
00080         if (trigger & 0x04) /* Button 3 down */
00081         {
00082           do_task(4);
00083           state = STATE_C;
00084         }
00085         trigger = 0; /* Ignore other triggers in this state */
00086         break;
00087 
00088       //////////////////////////////////////////////////////////////////
00089       case STATE_C:  ///////////////////////////////////////////////////
00090       //////////////////////////////////////////////////////////////////
00091         if (trigger & 0x04) /* Button 3 down */
00092         {
00093           do_task(5);
00094           state = STATE_A;
00095         }
00096         break;
00097     } /* while (!trigger) */
00098   } /* while (1) */
00099 }