sphinx/sphinx.c

   1 /*
   2  *      The Sphinx -- A Device for Asking Riddles at the Entrance to the 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  *      Note that MOSI is used for programming, so the LED is connected
  18  *      via jumper, which must be open during programming.
  19  */
  20
  21 #define F_CPU 1200000UL
  22
  23 #include <avr/interrupt.h>
  24 #include <avr/io.h>
  25 #include <avr/sleep.h>
  26 #include <util/delay.h>
  27
  28 typedef uint8_t byte;
  29 typedef uint16_t u16;
  30
  31 #define B(x) (1U<<(x))
  32
  33 static void sleep(uint16_t millisec)
  34 {
  35         while (millisec) {
  36                 _delay_ms(1);
  37                 millisec--;
  38         }
  39 }
  40
  41 static byte out_pulse;
  42 #define OUT_PULSE_WIDTH 100
  43 static byte debounce;
  44 #define DEBOUNCE_THRESHOLD 3
  45 static byte pressed;
  46 static u16 press_timer;
  47 #define LONG_PRESS 500
  48 static byte second_timer;
  49 static byte unlocked;
  50 #define UNLOCK_SECONDS 20
  51
  52 ISR(TIM0_COMPA_vect)
  53 {
  54         if (out_pulse) {
  55                 if (!--out_pulse)
  56                         PORTB &= ~B(PB4);
  57         }
  58
  59         if (!second_timer) {
  60                 second_timer = 100;
  61                 if (unlocked)
  62                         unlocked--;
  63         }
  64         second_timer--;
  65
  66         if (PINB & B(PB3)) {
  67                 // Switch open
  68                 if (debounce)
  69                         debounce--;
  70                 else
  71                         pressed = 0;
  72         } else {
  73                 // Switch closed
  74                 if (debounce < DEBOUNCE_THRESHOLD)
  75                         debounce++;
  76                 else
  77                         pressed = 1;
  78         }
  79
  80         if (unlocked) {
  81                 if (!(second_timer & 7))
  82                         PORTB ^= B(PB0);
  83                 if (pressed) {
  84                         if (out_pulse < 2)
  85                                 out_pulse = 2;
  86                         PORTB |= B(PB4);
  87                         unlocked = UNLOCK_SECONDS;
  88                 }
  89         } else {
  90                 if (!pressed) {
  91                         PORTB |= B(PB0);
  92                         press_timer = 0;
  93                 } else {
  94                         PORTB &= ~B(PB0);
  95                         if (press_timer < LONG_PRESS) {
  96                                 press_timer++;
  97                                 if (press_timer == LONG_PRESS) {
  98                                         out_pulse = OUT_PULSE_WIDTH;
  99                                         PORTB |= B(PB4);
 100                                         unlocked = UNLOCK_SECONDS;
 101                                 }
 102                         }
 103                 }
 104         }
 105 }
 106
 107 int main(void)
 108 {
 109         // PB0: output for diagnostic LED
 110         DDRB |= B(PB0);
 111
 112         // PB3: button input, needs pull up
 113         PORTB |= B(PB3);
 114
 115         // PB4: output to control the gate
 116         PORTB &= ~B(PB4);
 117         DDRB |= B(PB4);
 118
 119         for (byte i=0; i<5; i++) {
 120                 PORTB &= ~B(PB0);
 121                 sleep(50);
 122                 PORTB |= B(PB0);
 123                 sleep(50);
 124         }
 125
 126 #if 0
 127         // Copy mode
 128         for (;;) {
 129                 sleep(10);
 130                 if (PINB & B(PB3)) {
 131                         PORTB |= B(PB0);
 132                         PORTB &= ~B(PB4);
 133                 } else {
 134                         PORTB &= ~B(PB0);
 135                         PORTB |= B(PB4);
 136                 }
 137         }
 138 #endif
 139
 140         // Set up timer interrupt
 141         TCCR0A = 0x02;                  // No OC pins, clear on compare
 142         TCCR0B = 0x05;                  // Run at CLK_IO / 1024
 143         OCR0A = 11;                     // Approximately once in 10ms
 144         TIMSK0 = B(OCIE0A);             // Interrupt on compare
 145         sei();
 146
 147         // Sleep well, my little sphinx
 148         for (;;) {
 149                 set_sleep_mode(SLEEP_MODE_IDLE);
 150                 sleep_mode();
 151         }
 152 }