main.c

   1 #include <stdio.h>
   2 #include <wiringPi.h>
   3 #include <time.h>
   4 #define COIN_BUTTON 7
   5 #define CREDIT_EXTENSION 10
   6
   7 int expires = -1;
   8 int one_second_ago = 0;
   9
  10 void init_gpio()
  11 {
  12   wiringPiSetup();
  13   pinMode(COIN_BUTTON, INPUT);
  14   pullUpDnControl(COIN_BUTTON, PUD_UP);
  15 }
  16
  17 int now()
  18 {
  19   return (unsigned)time(NULL);
  20 }
  21
  22 int time_over()
  23 {
  24   if(one_second_ago != now() && expires != -1)
  25   {
  26     printf("You have %d seconds remaining\n", expires - now());
  27     one_second_ago = now();
  28   }
  29
  30   if(expires == now())
  31   {
  32     printf("It's all ogre now\n");
  33     expires = -1;
  34     return 1;
  35   }
  36
  37   return expires == -1;
  38 }
  39
  40 int read_button()
  41 {
  42   if(digitalRead(COIN_BUTTON) == LOW)
  43   {
  44     printf("Nice! I just added %d to your time.\n", CREDIT_EXTENSION);
  45
  46     //Increment timer
  47     if(expires == -1) //Initial credit, set the expiry to now plus time
  48     {
  49         expires = now() + CREDIT_EXTENSION;
  50     } else { //expiry already set, simply extend by time
  51         expires += CREDIT_EXTENSION;
  52     }
  53
  54     //wait for button to be released
  55     while(digitalRead(COIN_BUTTON) == LOW)
  56     {
  57        //I don't see this happening, but in principle if the button is held down
  58        //It would be possible to stop the switch happening after time runs out
  59        //So we must check for that here.
  60        if(time_over())
  61          break;
  62
  63        delay(10);
  64     }
  65
  66     return 1;
  67   }
  68
  69   return 0;
  70 }
  71
  72 int main (void)
  73 {
  74   init_gpio();
  75   printf ("Short pin 7 and 9 to increment timer.\n") ;
  76
  77   while(1)
  78   {
  79     read_button();
  80     //I don't really need to call this here but I'm doing it to see output.
  81     time_over();
  82     delay(10);
  83   }
  84 }