Subversion Repositories svnkaklik

/* 
 * Copyright (C) 2004 Darren Hutchinson (dbh@gbdt.com.au)
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Library General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
 * License for more details.
 * 
 * You should have received a copy of the GNU Library General Public License
 * along with this software; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA. 
 *
 * $Id: pguide.c,v 1.1.1.1 2004/02/22 08:12:42 dbh Exp $
 */

/* This file contains the code that takes inputs from a parallel output
 * guider (such as the SBIG ST-4) and uses them to make guiding
 * adjustments.
 */

#include <avr/io.h>
#include <avr/interrupt.h>
#include <inttypes.h>

#include "eq6.h"
#include "combine.h"
#include "pguide.h"

#define GUIDE_BITS      (_BV(G_UP) | _BV(G_DN) | _BV(G_RT) | _BV(G_LT))

/* This module polls the input bits from the guider, applies some
 * crude debouncing, and then applies the requested speed adjustment.
 *
 * This code assumes that the inputs are active low (i.e. they are connected
 * to a relay or optocoupler connecting the "active" input to ground).
 *
 * The polling rate is generated by a 8-bit timer with /256
 */

/* pguideInit() initializes the timer used to poll the parallel guiding
 * input bits and sets those bit as inputs.
 *
 * Passed:
 *      Nothing
 *
 * Returns:
 *      Nothing
 *
 */
void
pguideInit(void)
{
    /* Set guide bits as inputs with pullups */
    GUIDE_DDR &= ~GUIDE_BITS;
    GUIDE_PORT |= GUIDE_BITS;

    /* Setup timer 2 to generate interrupts for PWM to the selected
     * rate (in CTC mode)
     */
    OCR2 = (CLK_RATE / GUIDE_RATE / 1024);
    TCCR2 = _BV(WGM21) | _BV(CS22) | _BV(CS20);

    /* Enable interrupt generation from timer 2 */
    TIMSK |= _BV(OCIE2);
}

/* pguideInt() is called whenever a timer 2 overflow interrupt occurs
 *
 * Passed:
 *      Nothing
 *
 * Returns:
 *      Nothing
 */
SIGNAL(SIG_OUTPUT_COMPARE2)
{
    uint8_t             guideBits;

    static uint8_t      lastState = GUIDE_BITS;
    static uint8_t      lastUsed = GUIDE_BITS;

    /* Get the guide bits */
    guideBits = GUIDE_PIN & GUIDE_BITS;

    /* See if they're the same as the last set. If they are then we
     * assume that the guide bits are stable
     */
    if (guideBits != lastState)
    {
        /* Bits are changing */
        lastState = guideBits;
    }
    else if (lastUsed != lastState)
    {
        /* They're stable and different from the last used set, so
         * update the guiding information
         */

        if ((guideBits & _BV(G_UP)) == 0)
            rateInput.guideDecRate = SPEED_0_33_X;
        else if ((guideBits & _BV(G_DN)) == 0)
            rateInput.guideDecRate = -SPEED_0_33_X;
        else
            rateInput.guideDecRate = SPEED_0_X;

        if ((guideBits & _BV(G_RT)) == 0)
            rateInput.guideRaRate = SPEED_0_33_X;
        else if ((guideBits & _BV(G_LT)) == 0)
            rateInput.guideRaRate = -SPEED_0_33_X;
        else
            rateInput.guideRaRate = SPEED_0_X;
        
        /* Update the overall rate */
        updateMountSpeed();

        /* Update the last used state ('cuz we used it) */
        lastUsed = lastState;
    }
}