firmware/firmware.c

   1 #include <avr/io.h>
   2 #include <avr/interrupt.h>
   3 #include <util/delay.h>
   4 #include <stdio.h>
   5 #include "clock.h"
   6 #include "modbus.h"
   7
   8 #define ECHO_TIMEOUT            (CLOCK_HZ/10)   // 10 ms
   9 #define MEASUREMENT_WAIT        (CLOCK_HZ/3)    // three triggers per second
  10
  11 #define N_TRIGGERS 3
  12 #define N_SENSORS 12
  13 #define N_TRIG_SENSORS 4
  14
  15 // static int16_t distances[N_SENSORS];
  16
  17 // hold_regs[0] is unit ID
  18 #define thresholds      (hold_regs+1)
  19 #define led1_sensors    (hold_regs[13])
  20 #define led2_sensors    (hold_regs[14])
  21
  22 #define led_bitmap      (hold_regs[MB_N_HOLD_REGS_EEPROM])
  23 #define distances       (hold_regs+MB_N_HOLD_REGS_EEPROM+1)
  24 #define free_bitmap     (hold_regs[MB_N_HOLD_REGS_EEPROM+13])
  25 #define err_bitmap      (hold_regs[MB_N_HOLD_REGS_EEPROM+14])
  26
  27 static void pull_trigger(uint8_t trig)
  28 {
  29         switch (trig) {
  30         case 0: PORTD |= _BV(PD7); _delay_us(10); PORTD &= ~_BV(PD7); break;
  31         case 1: PORTB |= _BV(PB4); _delay_us(10); PORTB &= ~_BV(PB4); break;
  32         case 2: PORTC |= _BV(PC4); _delay_us(10); PORTC &= ~_BV(PC4); break;
  33         }
  34 }
  35
  36 static uint16_t get_pin(uint8_t trig)
  37 {
  38         switch (trig) {
  39         case 0: return (PIND & 0x78) >> 3;
  40         case 1: return PINB & 0x0F;
  41         default: return PINC & 0x0F;
  42         }
  43 }
  44
  45 static void do_measurement(unsigned char trig)
  46 {
  47         uint16_t starttimes[N_TRIG_SENSORS], starttime;
  48         uint8_t to_start = (1 << N_TRIG_SENSORS) - 1;
  49         uint8_t to_measure = 0, i;
  50
  51         pull_trigger(trig);
  52
  53         starttime = get_clock();
  54
  55         while (to_start || to_measure) {
  56                 uint8_t bits = 0;
  57                 uint16_t now = get_clock();
  58
  59                 if (now-starttime >= ECHO_TIMEOUT)
  60                         break;
  61
  62                 bits = get_pin(trig);
  63
  64                 for (i = 0; i < N_TRIG_SENSORS; i++) {
  65                         uint8_t mask = 1 << i;
  66
  67                         if ((to_start & mask) && (bits & mask)) {
  68                                 // echo start
  69                                 starttimes[i] = now;
  70                                 to_start &= ~mask;
  71                                 to_measure |= mask;
  72                         } else if ((to_measure & mask) && !(bits & mask)) {
  73                                 // echo end
  74                                 to_measure &= ~mask;
  75                                 distances[trig*N_TRIG_SENSORS + i]
  76                                         = now - starttimes[i];
  77                         }
  78                 }
  79         }
  80
  81         for (i = 0; i < N_TRIG_SENSORS; i++)
  82                 if (to_start & (1 << i))
  83                         distances[trig*N_TRIG_SENSORS + i] = -1;
  84                 else if (to_measure & (1 << i))
  85                         distances[trig*N_TRIG_SENSORS + i] = 0;
  86 }
  87
  88 static void led_set(uint8_t led, uint8_t state)
  89 {
  90         if (led == 0) {
  91                 if (state) {
  92                         PORTC |= _BV(PC5);
  93                         led_bitmap |= 1;
  94                 } else {
  95                         PORTC &= ~_BV(PC5);
  96                         led_bitmap &= ~1;
  97                 }
  98         } else {
  99                 if (state) {
 100                         PORTB |= _BV(PB5);
 101                         led_bitmap |= 2;
 102                 } else {
 103                         PORTB &= ~_BV(PB5);
 104                         led_bitmap &= ~2;
 105                 }
 106         }
 107 }
 108
 109 static void eval_bitmaps()
 110 {
 111         uint16_t free_b = 0, err_b = 0, mask;
 112         uint8_t i;
 113
 114         for (i = 0; i < N_SENSORS; i++) {
 115                 mask = 1 << i;
 116
 117                 if (thresholds[i]) {
 118                         if (distances[i] == -1 || distances[i] == 0) {
 119                                 err_b |= mask;
 120                         } else if (distances[i] > thresholds[i]) {
 121                                 free_b |= mask;
 122                         }
 123                 }
 124         }
 125
 126         free_bitmap = free_b;
 127         err_bitmap  = err_b;
 128
 129         if (led1_sensors) {
 130                 if (led1_sensors & free_bitmap) {
 131                         led_set(0, 1);
 132                 } else {
 133                         led_set(0, 0);
 134                 }
 135         }
 136
 137         if (led2_sensors) {
 138                 if (led2_sensors & free_bitmap) {
 139                         led_set(1, 1);
 140                 } else {
 141                         led_set(1, 0);
 142                 }
 143         }
 144 }
 145
 146 uint8_t hold_reg_is_valid(uint16_t reg, uint16_t val)
 147 {
 148         if (reg == MB_HOLD_REGS_BASE)
 149                 return val > 0 && val <= 247;
 150
 151         return 1;
 152 }
 153
 154 int main()
 155 {
 156         modbus_init(0);
 157
 158         // output pins
 159         DDRD |= _BV(PD7); // Trig D
 160         DDRB |= _BV(PB4) | _BV(PB5); // Trig B, LED 2
 161         DDRC |= _BV(PC4) | _BV(PC5); // Trig C, LED 1
 162
 163         // set up the timer
 164         TCCR1A = 0;
 165         TCCR1B = _BV(CS12)|_BV(CS10); // CLK/1024
 166
 167         // enable interrupts
 168         sei();
 169
 170         while(1) {
 171                 uint8_t trig;
 172                 for (trig = 0; trig < N_TRIGGERS; trig++) {
 173                         uint16_t now;
 174                         do_measurement(trig);
 175                         now = get_clock();
 176                         while (get_clock()-now < MEASUREMENT_WAIT)
 177                                 modbus_poll();
 178                 }
 179
 180                 eval_bitmaps();
 181 //              led_set(0,
 182 //                      distances[4] > 100 || distances[11] > 100);
 183         }
 184 }
 185