Colony » Colony Scout » Colony Scout OS

#include <stdint.h>

#include <avr/io.h>

#include <avr/interrupt.h>

#include "twi.h"

#include "bomi2c.h"

#define QUEUE_SIZE 64

uint16_t queue[QUEUE_SIZE];

int queue_idx;

char last_bit;

char count;

uint16_t data;

volatile char currently_sending;

char sending_counter;

uint16_t sending_data;

#define READ_BIT(pin, bit) (((pin) >> bit) & 1)

#define SET_BIT(pin, bit) ((pin) |= (1 << (bit)))

#define CLEAR_BIT(pin, bit) ((pin) &= ~(1 << (bit)))

#define PRESCALAR 8

#define TIME_US(us) (F_CPU * (us) / 1000000 / PRESCALAR)

static void slave_tx(void) {

  twi_transmit((uint8_t*)queue, queue_idx * sizeof(queue[0]));

  queue_idx = 0;

}

static void slave_rx(uint8_t *buf, int len) {

  if (len > 0) {

    switch (buf[0]) {

      case BOM_I2C_SEND:

        // TODO

        break;

    }

  }

}

static void bom_start(void) {

  data = 0;

  count = 0;

  last_bit = 1;

  // TODO disable interrupt

  // TODO start timer

}

static void bom_stop(void) {

  // TODO stop timer

  // TODO restart INT0

}

static void bom_init(void) {

  // setup INT0

  //EICRA |= _BV(ISC01) | _BV(ISC00);

  //EIMSK |= _BV(INT0);

  // setup timer 0

  TCCR0B |= _BV(CS01);

  TIMSK |= _BV(OCIE0A);

  // setup timer 1 for output

  OCR1B = TIME_US(320); // Set match b to fire every 320 us

  TIMSK |= _BV(OCIE1A) | _BV(OCIE1B); // Enable interrupt for match a and b

  TCCR1 |= _BV(CTC1);   // Enables resetting timer1 after matches match c

  // setup output pin

  SET_BIT(DDRB, 4);

  sei();

  bom_start();

}

ISR(TIMER0_COMPA_vect) {

  char this_bit = READ_BIT(PINB, PB2);

  if (this_bit == 0) {

    if (last_bit == 0) {

      bom_stop();

    }

  } else {

    data = data << 1 | (~last_bit & 1);

    count++;

  }

  last_bit = this_bit;

  if (count == 15) {

    if (queue_idx < QUEUE_SIZE) {

      queue[queue_idx] = data;

      queue_idx++;

    }

    bom_stop();

  }

}

static void send_next_bit() {

  char next_bit = sending_data >> (14 - sending_counter) & 1;

  char ocr_temp = next_bit ? TIME_US(2000-40) : TIME_US(1000-20);

  OCR1A = ocr_temp;

  OCR1C = ocr_temp;

}

ISR(TIMER1_COMPA_vect) {

  SET_BIT(PORTB, PB4);

  sending_counter++;

  send_next_bit();

}

ISR(TIMER1_COMPB_vect) {

  CLEAR_BIT(PORTB, PB4);

  if (sending_counter >= 15) {

    currently_sending = 0;

    TCCR1 &= ~0x0F; // Stop the timer without clearing CTC1

  }

}

static void send_data(uint16_t data) {

  sending_data = data;

  sending_counter = 0;

  currently_sending = 1;

  TCNT1 = 0;

  TCCR1 |= _BV(CS12);  // Set prescalar to 8 and start timer

  SET_BIT(PORTB, PB4);

  send_next_bit();

  while (currently_sending) { }

}

ISR(INT0_vect) {

  bom_start();

}

// temporary for testing

#include <util/delay.h>

int main() {

  bom_init();

  for (;;) {

    send_data(4513);

    _delay_ms(100);

  }

}