Directory layout

[openparking.git] / firmware / firmware.c

diff --git a/firmware/firmware.c b/firmware/firmware.c
new file mode 100755 (executable)
index 0000000..67508e6
--- /dev/null
+++ b/firmware/firmware.c
@@ -0,0 +1,139 @@
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <util/delay.h>
+#include <stdio.h>
+#include "rs485.h"
+
+#define TIMEOUT 0x2FF
+
+#define N_TRIGGERS 3
+#define N_SENSORS 12
+#define N_TRIG_SENSORS 4
+
+static int16_t distances[N_SENSORS];
+
+static void pull_trigger(uint8_t trig)
+{
+       switch (trig) {
+       case 0: PORTD |= _BV(PD7); _delay_us(10); PORTD &= ~_BV(PD7); break;
+       case 1: PORTB |= _BV(PB4); _delay_us(10); PORTB &= ~_BV(PB4); break;
+       case 2: PORTC |= _BV(PC4); _delay_us(10); PORTC &= ~_BV(PC4); break;
+       }
+}
+
+static uint16_t get_pin(uint8_t trig)
+{
+       switch (trig) {
+       case 0: return (PIND & 0x78) >> 3;
+       case 1: return PINB & 0x0F;
+       default: return PINC & 0x0F;
+       }
+}
+
+static void do_measurement(unsigned char trig)
+{
+       uint16_t starttimes[N_TRIG_SENSORS], starttime;
+       uint8_t to_start = (1 << N_TRIG_SENSORS) - 1;
+       uint8_t to_measure = 0, i;
+
+       pull_trigger(trig);
+
+       starttime = TCNT1;
+
+       while (to_start || to_measure) {
+               uint8_t bits = 0;
+               uint16_t now = TCNT1;
+
+               if (now-starttime >= TIMEOUT)
+                       break;
+
+               bits = get_pin(trig);
+
+               for (i = 0; i < N_TRIG_SENSORS; i++) {
+                       uint8_t mask = 1 << i;
+
+                       if ((to_start & mask) && (bits & mask)) {
+                               // echo start
+                               starttimes[i] = now;
+                               to_start &= ~mask;
+                               to_measure |= mask;
+                       } else if ((to_measure & mask) && !(bits & mask)) {
+                               // echo end
+                               to_measure &= ~mask;
+                               distances[trig*N_TRIG_SENSORS + i]
+                                       = now - starttimes[i];
+                       }
+               }
+       }
+
+       for (i = 0; i < N_TRIG_SENSORS; i++)
+               if (to_start & (1 << i))
+                       distances[trig*N_TRIG_SENSORS + i] = -1;
+               else if (to_measure & (1 << i))
+                       distances[trig*N_TRIG_SENSORS + i] = 0;
+}
+
+static void do_measurements()
+{
+       uint8_t trig;
+
+       for (trig = 0; trig < N_TRIGGERS; trig++) {
+               do_measurement(trig);
+               _delay_ms(200);
+       }
+}
+
+static void led_set(uint8_t led, uint8_t state)
+{
+       if (led == 0) {
+               if (state) {
+                       PORTD |= _BV(PD4);
+                       // PORTC |= _BV(PC5);
+               } else {
+                       PORTD &= ~_BV(PD4);
+                       // PORTC &= ~_BV(PC5);
+               }
+       } else {
+               if (state) {
+                       PORTB |= _BV(PB5);
+               } else {
+                       PORTB &= ~_BV(PB5);
+               }
+       }
+}
+
+int main()
+{
+       char obuf[120];
+
+       rs485_init();
+
+       // output pins
+       DDRD |= _BV(PD7); // Trig D
+       DDRB |= _BV(PB4) | _BV(PB5); // Trig B, LED 2
+       DDRC |= _BV(PC4) | _BV(PC5); // Trig C, LED 1
+       // temporary LED
+       DDRD |= _BV(PD4);
+
+       // set up the timer
+       TCCR1A = 0;
+       TCCR1B = _BV(CS12)|_BV(CS10); // CLK/1024
+
+       // enable interrupts
+       sei();
+
+       while(1) {
+               do_measurements();
+
+               sprintf(obuf, "%3d %3d %3d %3d %3d %3d %3d %3d %3d %3d %3d %3d\r\n",
+                       distances[0], distances[1], distances[2],
+                       distances[3], distances[4], distances[5],
+                       distances[6], distances[7], distances[8],
+                       distances[9], distances[10], distances[11]);
+
+               rs485_send(obuf);
+               led_set(0,
+                       distances[4] > 100 || distances[11] > 100);
+       }
+}
+