firmware/firmware.c

   1 #include <avr/io.h>
   2 #include <avr/interrupt.h>
   3 #include <util/delay.h>
   4 #include <stdio.h>
   5 #include "rs485.h"
   6
   7 #define TIMEOUT 0x2FF
   8
   9 #define N_TRIGGERS 3
  10 #define N_SENSORS 12
  11 #define N_TRIG_SENSORS 4
  12
  13 static int16_t distances[N_SENSORS];
  14
  15 static void pull_trigger(uint8_t trig)
  16 {
  17         switch (trig) {
  18         case 0: PORTD |= _BV(PD7); _delay_us(10); PORTD &= ~_BV(PD7); break;
  19         case 1: PORTB |= _BV(PB4); _delay_us(10); PORTB &= ~_BV(PB4); break;
  20         case 2: PORTC |= _BV(PC4); _delay_us(10); PORTC &= ~_BV(PC4); break;
  21         }
  22 }
  23
  24 static uint16_t get_pin(uint8_t trig)
  25 {
  26         switch (trig) {
  27         case 0: return (PIND & 0x78) >> 3;
  28         case 1: return PINB & 0x0F;
  29         default: return PINC & 0x0F;
  30         }
  31 }
  32
  33 static void do_measurement(unsigned char trig)
  34 {
  35         uint16_t starttimes[N_TRIG_SENSORS], starttime;
  36         uint8_t to_start = (1 << N_TRIG_SENSORS) - 1;
  37         uint8_t to_measure = 0, i;
  38
  39         pull_trigger(trig);
  40
  41         starttime = TCNT1;
  42
  43         while (to_start || to_measure) {
  44                 uint8_t bits = 0;
  45                 uint16_t now = TCNT1;
  46
  47                 if (now-starttime >= TIMEOUT)
  48                         break;
  49
  50                 bits = get_pin(trig);
  51
  52                 for (i = 0; i < N_TRIG_SENSORS; i++) {
  53                         uint8_t mask = 1 << i;
  54
  55                         if ((to_start & mask) && (bits & mask)) {
  56                                 // echo start
  57                                 starttimes[i] = now;
  58                                 to_start &= ~mask;
  59                                 to_measure |= mask;
  60                         } else if ((to_measure & mask) && !(bits & mask)) {
  61                                 // echo end
  62                                 to_measure &= ~mask;
  63                                 distances[trig*N_TRIG_SENSORS + i]
  64                                         = now - starttimes[i];
  65                         }
  66                 }
  67         }
  68
  69         for (i = 0; i < N_TRIG_SENSORS; i++)
  70                 if (to_start & (1 << i))
  71                         distances[trig*N_TRIG_SENSORS + i] = -1;
  72                 else if (to_measure & (1 << i))
  73                         distances[trig*N_TRIG_SENSORS + i] = 0;
  74 }
  75
  76 static void do_measurements()
  77 {
  78         uint8_t trig;
  79
  80         for (trig = 0; trig < N_TRIGGERS; trig++) {
  81                 do_measurement(trig);
  82                 _delay_ms(200);
  83         }
  84 }
  85
  86 static void led_set(uint8_t led, uint8_t state)
  87 {
  88         if (led == 0) {
  89                 if (state) {
  90                         PORTD |= _BV(PD4);
  91                         // PORTC |= _BV(PC5);
  92                 } else {
  93                         PORTD &= ~_BV(PD4);
  94                         // PORTC &= ~_BV(PC5);
  95                 }
  96         } else {
  97                 if (state) {
  98                         PORTB |= _BV(PB5);
  99                 } else {
 100                         PORTB &= ~_BV(PB5);
 101                 }
 102         }
 103 }
 104
 105 int main()
 106 {
 107         char obuf[120];
 108
 109         rs485_init();
 110
 111         // output pins
 112         DDRD |= _BV(PD7); // Trig D
 113         DDRB |= _BV(PB4) | _BV(PB5); // Trig B, LED 2
 114         DDRC |= _BV(PC4) | _BV(PC5); // Trig C, LED 1
 115         // temporary LED
 116         DDRD |= _BV(PD4);
 117
 118         // set up the timer
 119         TCCR1A = 0;
 120         TCCR1B = _BV(CS12)|_BV(CS10); // CLK/1024
 121
 122         // enable interrupts
 123         sei();
 124
 125         while(1) {
 126                 do_measurements();
 127
 128                 sprintf(obuf, "%3d %3d %3d %3d %3d %3d %3d %3d %3d %3d %3d %3d\r\n",
 129                         distances[0], distances[1], distances[2],
 130                         distances[3], distances[4], distances[5],
 131                         distances[6], distances[7], distances[8],
 132                         distances[9], distances[10], distances[11]);
 133
 134                 rs485_send(obuf);
 135                 led_set(0,
 136                         distances[4] > 100 || distances[11] > 100);
 137         }
 138 }
 139