main.cpp

00001 #include "mbed.h"
00002 
00003 DigitalOut gpo(PTD7);
00004 DigitalOut led(LED_RED);
00005 
00006 InterruptIn trig(PTD1);
00007 Timer trigtimer;
00008 Timeout output_timeout;
00009 Timeout input_timeout;
00010 
00011 
00012 typedef enum {TRIG_DETECT_IDLE, TRIG_LOW, TRIG_FIRST_HIGH} trig_enum_t;
00013 typedef enum {TRIG_EVENT_RISING, TRIG_EVENT_FALLING, TRIG_EVENT_TIMEOUT} trig_event_t;
00014 
00015 trig_enum_t trigger = TRIG_DETECT_IDLE;
00016 
00017 //Function declarations
00018 void input_timeout_handler(void);
00019 void get_new_state(trig_enum_t * trig, trig_event_t event);
00020 void set_output(void);
00021 void trig_rise_event(void);
00022 void trig_fall_event(void);
00023 
00024 
00025 
00026 void input_timeout_handler(void)
00027 {
00028     get_new_state(&trigger, TRIG_EVENT_TIMEOUT);
00029 }
00030 
00031 void get_new_state(trig_enum_t * trig, trig_event_t event)
00032 {
00033     const int jitter = 8;
00034     switch(*trig)
00035     {
00036     case TRIG_DETECT_IDLE:
00037     {
00038         if(event == TRIG_EVENT_FALLING)
00039         {
00040             *trig = TRIG_LOW;
00041             trigtimer.reset();
00042         }
00043         else // should not happen
00044             *trig = TRIG_DETECT_IDLE;
00045         break;
00046     }
00047     case TRIG_LOW:
00048     {
00049         if(event == TRIG_EVENT_RISING)
00050         {
00051             if(trigtimer.read_us() > (30 - jitter) && trigtimer.read_us() < (30+jitter) ) //if first low period detected
00052             {
00053                 *trig = TRIG_FIRST_HIGH;
00054                 input_timeout.attach_us(input_timeout_handler, 60);
00055             }
00056             else //pulse too short or too long
00057                 *trig = TRIG_DETECT_IDLE;      
00058         }
00059         
00060         else // should not happen
00061             *trig = TRIG_DETECT_IDLE;
00062         break;
00063     }
00064     case TRIG_FIRST_HIGH:
00065     {
00066         led=!led;
00067         if(event == TRIG_EVENT_TIMEOUT)
00068         {
00069            gpo.write(0);
00070            output_timeout.attach_us(set_output, 1000);
00071            *trig = TRIG_DETECT_IDLE;
00072         }
00073         
00074         else // should not happen, maybe falling edge due to TOP684
00075         {
00076             *trig = TRIG_DETECT_IDLE;
00077             input_timeout.detach();
00078         }
00079         break;
00080     } 
00081     default:
00082         break;
00083     }
00084         
00085 }
00086      
00087 
00088 void set_output(void)
00089 {
00090     gpo.write(1);
00091 }
00092 
00093 
00094 void trig_rise_event(void)
00095 {
00096      get_new_state(&trigger, TRIG_EVENT_RISING);
00097 }
00098 
00099 
00100 void trig_fall_event(void)
00101 {
00102     get_new_state(&trigger, TRIG_EVENT_FALLING);
00103 
00104 }    
00105 
00106 int main()
00107 {
00108     trigtimer.start();
00109     trig.rise(trig_rise_event);
00110     trig.fall(trig_fall_event);
00111     while (true) {
00112         //gpo = !gpo; // toggle pin
00113         //led = !led; // toggle led
00114         wait(0.2f);
00115     }
00116 }