/*
 * $Id: main.c,v 1.1 2010/10/19 05:18:47 bsd Exp $
 *
 */

/*
 * CMPS03 - a complete test program using the CMPS03 on the BDMICRO
 * MAVRIC and MAVRIC-II microcontroller boards.  This program is
 * intended to demonstrate how to use the BDMICRO MAVRIC or MAVRIC-II
 * microcontroller boards in conjunction with CMPS03 Compass Module.
 * Feel free to copy the relevent function definitions into your own
 * applications and to customize them for your needs.
 *
 * See: http://www.bdmicro.com/
 *
 * Configuration:
 *
 *   Simply attach your CMPS03 Compass Module to your board's I2C bus,
 *   power, and ground.  It's OK to use one of the supplied VCC pins
 *   on your microcontroller board to supply power to the SRF08.
 *
 *   If desired, attach a terminal to UART0 for 9600, 8N1; the CMPS03
 *   will be read once per second and the result in degrees will be
 *   printed to UART0.
 * 
 */

#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/twi.h>

#include <stdio.h>

#include "cmps03.h"
#include "i2c.h"

#define BAUD_RR ((CPU_FREQ/(16L*9600L) - 1))


#define CPU_FREQ 16000000L  /* set to clock frequency in Hz */

#if CPU_FREQ == 16000000L
#define OCR_1MS 125
#elif CPU_FREQ == 14745600L
#define OCR_1MS 115
#endif


volatile uint16_t ms_count;

/*
 * ms_sleep() - delay for specified number of milliseconds
 */
void ms_sleep(uint16_t ms)
{
  TCNT0  = 0;
  ms_count = 0;
  while (ms_count != ms)
    ;
}


/* 
 * millisecond counter interrupt vector 
 */
SIGNAL(SIG_OUTPUT_COMPARE0)
{
  ms_count++;
}


/*
 * Initialize timer0 to use the main crystal clock and the output
 * compare interrupt feature to generate an interrupt approximately
 * once per millisecond to use as a general purpose time base.
 */
void init_timer0(void)
{
  TCCR0 = 0;
  TIFR  |= _BV(OCIE0)|_BV(TOIE0);
  TIMSK |= _BV(TOIE0)|_BV(OCIE0);         /* enable output compare interrupt */
  TCCR0  = _BV(WGM01)|_BV(CS02)|_BV(CS00); /* CTC, prescale = 128 */
  TCNT0  = 0;
  OCR0   = OCR_1MS;                     /* match in aprox 1 ms */
}




int def_putc(char ch, FILE * f)
{
  /* output character to UART0 */
  while ((UCSR0A & _BV(UDRE)) == 0)
    ;
  UDR0 = ch;
  return 0;
}




int main(void)
{
  int16_t b16;
  uint8_t b8;
  double dir;

  init_timer0();

  /* enable UART0 */
  UBRR0H = (BAUD_RR >> 8) & 0xff;
  UBRR0L = BAUD_RR & 0xff;
  UCSR0B = _BV(TXEN); /* enable transmitter only */

  /* enable interrupts */
  sei();

  /* initialize stdio */
  fdevopen(def_putc, NULL);

  /* set the I2C bit rate generator to 100 kb/s */
  TWSR &= ~0x03;
  TWBR  = 28;
  TWCR |= _BV(TWEN);

  while (1) {
    ms_sleep(1000);

    b16 = bearing16();
    if (b16 >= 0) {
      dir = ((double)b16) / 10.0;
      printf("bearing (16) = %0.1f degrees\n", dir);
    }

    b8 = bearing8();
    dir = ((double)b8) * 1.40625;
    printf("bearing (8)  = %0.1f degrees\n", dir);
    printf("\n");
  }
}