sphinx/sphinx.c

   1 /*
   2  *      Asking Riddles at the Entrance to Garage
   3  *
   4  *      (c) 2017 Martin Mares <mj@ucw.cz>
   5  */
   6
   7 /*
   8  *      Pin assignment (component side view; "*" marks inverted signals)
   9  *
  10  *                      +-------------------+
  11  *                      | RESET*        VCC |
  12  *      button          | PB3           SCK |
  13  *      output          | PB4          MISO |
  14  *                      | GND      PB0=MOSI |   diagnostic LED*
  15  *                      +-------------------+
  16  */
  17
  18 #define F_CPU 1200000UL
  19
  20 #include <avr/io.h>
  21 #include <avr/sleep.h>
  22 #include <util/delay.h>
  23
  24 typedef uint8_t byte;
  25
  26 #define B(x) (1U<<(x))
  27
  28 static void sleep(uint16_t millisec)
  29 {
  30         while (millisec) {
  31                 _delay_ms(1);
  32                 millisec--;
  33         }
  34 }
  35
  36 int main(void)
  37 {
  38         DDRB |= B(PB0);                 // PB0: output
  39         DDRB |= B(PB4);                 // PB4: output
  40         PORTB &= ~B(PB3);               // PB3: input, no pullup
  41
  42         for (byte i=0; i<5; i++) {
  43                 PORTB &= ~B(PB0);
  44                 sleep(100);
  45                 PORTB |= B(PB0);
  46                 sleep(100);
  47         }
  48
  49         for (;;) {
  50                 sleep(10);
  51                 if (PINB & B(PB3)) {
  52                         PORTB &= ~B(PB0);
  53                         PORTB |= B(PB4);
  54                 } else {
  55                         PORTB |= B(PB0);
  56                         PORTB &= ~B(PB4);
  57                 }
  58         }
  59
  60         for (;;) {
  61                 set_sleep_mode(SLEEP_MODE_PWR_DOWN);
  62                 sleep_mode();
  63         }
  64 }