tenar/tenar.c

   1 /*
   2  *      Waking Up Ogion
   3  *
   4  *      (c) 2013 Martin Mares <mj@ucw.cz>
   5  */
   6
   7 /*
   8  *      Pin assignment (component side view; "*" marks inverted signals)
   9  *
  10  *                      +-------------------+
  11  *                      | RESET*        VCC |
  12  *      diagnostic LED* | PB3           SCK |
  13  *      output RESET*   | PB4          MISO |
  14  *                      | GND          MOSI |
  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         PORTB &= ~B(PB4);               // PB4: tri-stated
  39         DDRB |= B(PB3);                 // PB3: output
  40
  41         for (byte i=0; i<5; i++) {
  42                 PORTB &= ~B(PB3);
  43                 sleep(100);
  44                 PORTB |= B(PB3);
  45                 sleep(900);
  46         }
  47
  48         PORTB &= ~B(PB3);
  49         DDRB |= B(PB4);                 // PB4: output 0
  50         sleep(300);
  51         DDRB &= ~B(PB4);                // PB4: tri-state
  52         DDRB &= ~B(PB3);                // PB3: tri-state to save power
  53
  54         for (;;) {
  55                 set_sleep_mode(SLEEP_MODE_PWR_DOWN);
  56                 sleep_mode();
  57         }
  58 }