main.cpp

00001 /* 
00002 
00003 Task1_FSM_Counter
00004 
00005 Sample code from ELEC2645 Week 16 Lab
00006 
00007 Demonstrates how to implement a simple FSM counter
00008 
00009 (c) Bonny Ngangu, University of Leeds, Jan 2016
00010 
00011 */ 
00012 
00013 #include "mbed.h"
00014 
00015 // K64F on-board 4 LEDs 
00016 DigitalOut r_led(LED_RED);
00017 DigitalOut g_led(LED_GREEN);
00018 DigitalOut b_led(LED_BLUE);
00019 DigitalOut y_led(LED_BLUE);
00020 
00021 // K64F on-board switches
00022 InterruptIn sw2(SW2);
00023 InterruptIn sw3(SW3);
00024 
00025 // LEDs to display counter output
00026 // connect up external LEDs to these pins with appropriate current-limiting resistor
00027 BusOut output(PTB2,PTB3,PTB10,PTB11);
00028 
00029 // array of states in the FSM, each element is the output of the counter
00030 int fsm[4] = {8,4,2,1}; //reversed order counter going down
00031 
00032 // function prototypes
00033 // error function hangs flashing an LED
00034 void error();
00035 // set-up the on-board LEDs and switches
00036 void init_K64F();
00037 
00038 int main()
00039 {
00040     init_K64F();
00041     // set inital state 
00042     int state = 0;
00043 
00044     while(1) {  // loop forever
00045 
00046         output = fsm[state];  // output current state
00047 
00048         // check which state we are in and see which the next state should be
00049         switch(state) {
00050             case 0://0
00051                 state = 1;//1
00052                 break;
00053             case 1://1
00054                 state = 2;//2
00055                 break;
00056             case 2://2
00057                 state = 3;//3
00058                 break;
00059             case 3://3
00060                 state = 0;//0
00061                 break;
00062             default:
00063                 error();  //invalid state - call error routine
00064                 // or could jump to starting state i.e. state = 0
00065                 break;  
00066         }
00067 
00068         wait(0.2);  // small delay
00069 
00070     }
00071 }
00072 
00073 void init_K64F() 
00074 {
00075     // on-board LEDs are active-low, so set pin high to turn them off.
00076     r_led = 1;
00077     g_led = 1;
00078     b_led = 1;
00079     y_led = 1;   
00080     
00081     // since the on-board switches have external pull-ups, we should disable the internal pull-down
00082     // resistors that are enabled by default using InterruptIn
00083     sw2.mode(PullNone);
00084     sw3.mode(PullNone);
00085 
00086 }
00087 
00088 void error()
00089 {
00090     while(1) {  // if error, hang while flashing error message
00091         r_led = 0;
00092         wait(0.2);
00093         r_led = 1;
00094         wait(0.2);    
00095     }    
00096 }