flightgear/src/Network/atc610x.cxx

// atc610x.cxx -- FGFS interface to ATC 610x hardware
//
// Written by Curtis Olson, started January 2002
//
// Copyright (C) 2002  Curtis L. Olson - http://www.flightgear.org/~curt
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU 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
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
//
// $Id$


#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif

#include <simgear/compiler.h>

#include <stdlib.h>		// atoi() atof() abs()
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>              //snprintf
#if defined( _MSC_VER ) || defined(__MINGW32__)
#  include <io.h>                 //lseek, read, write
#endif

#include STL_STRING

#include <plib/ul.h>

#include <simgear/debug/logstream.hxx>
#include <simgear/io/iochannel.hxx>
#include <simgear/math/sg_types.hxx>
#include <simgear/misc/sg_path.hxx>
#include <simgear/props/props.hxx>

#include <Scripting/NasalSys.hxx>
#include <Main/fg_props.hxx>
#include <Main/globals.hxx>

#include "atc610x.hxx"

SG_USING_STD(string);


// Lock the ATC 610 hardware
static int ATC610xLock( int fd ) {
    // rewind
    lseek( fd, 0, SEEK_SET );

    char tmp[2];
    int result = read( fd, tmp, 1 );
    if ( result != 1 ) {
	SG_LOG( SG_IO, SG_DEBUG, "Lock failed" );
    }

    return result;
}


// Write a radios command
static int ATC610xRelease( int fd ) {
    // rewind
    lseek( fd, 0, SEEK_SET );

    char tmp[2];
    tmp[0] = tmp[1] = 0;
    int result = write( fd, tmp, 1 );

    if ( result != 1 ) {
	SG_LOG( SG_IO, SG_DEBUG, "Release failed" );
    }

    return result;
}


// Write a radios command
static int ATC610xSetRadios( int fd,
			     unsigned char data[ATC_RADIO_DISPLAY_BYTES] )
{
    // rewind
    lseek( fd, 0, SEEK_SET );

    int result = write( fd, data, ATC_RADIO_DISPLAY_BYTES );

    if ( result != ATC_RADIO_DISPLAY_BYTES ) {
	SG_LOG( SG_IO, SG_DEBUG, "Write failed" );
    }

    return result;
}


// Write a stepper command
static int ATC610xSetStepper( int fd, unsigned char channel,
			      unsigned char value )
{
    // rewind
    lseek( fd, 0, SEEK_SET );

    // Write the value
    unsigned char buf[3];
    buf[0] = channel;
    buf[1] = value;
    buf[2] = 0;
    int result = write( fd, buf, 2 );
    if ( result != 2 ) {
	SG_LOG( SG_IO, SG_INFO, "Write failed" );
    }
    SG_LOG( SG_IO, SG_DEBUG,
	    "Sent cmd = " << (int)channel << " value = " << (int)value );
    return result;
}


// Read status of last stepper written to
static unsigned char ATC610xReadStepper( int fd ) {
    int result;

    // rewind
    lseek( fd, 0, SEEK_SET );

    // Write the value
    unsigned char buf[2];
    result = read( fd, buf, 1 );
    if ( result != 1 ) {
	SG_LOG( SG_IO, SG_ALERT, "Read failed" );
	exit( -1 );
    }
    SG_LOG( SG_IO, SG_DEBUG, "Read result = " << (int)buf[0] );

    return buf[0];
}


// Turn a lamp on or off
void ATC610xSetLamp( int fd, int channel, bool value ) {
    // lamp channels 0-63 are written to LampPort0, channels 64-127
    // are written to LampPort1

    // bits 0-6 are the lamp address
    // bit 7 is the value (on/off)

    int result;

    // Write the value
    unsigned char buf[3];
    buf[0] = channel;
    buf[1] = value;
    buf[2] = 0;
    result = write( fd, buf, 2 );
    if ( result != 2 ) {
        SG_LOG( SG_IO, SG_ALERT,  "Write failed" );
        exit( -1 );
    }
}


void FGATC610x::init_config() {
#if defined( unix ) || defined( __CYGWIN__ )
    // Next check home directory for .fgfsrc.hostname file
    char *envp = ::getenv( "HOME" );
    if ( envp != NULL ) {
        SGPath atc610x_config( envp );
        atc610x_config.append( ".fgfs-atc610x.xml" );
        readProperties( atc610x_config.str(), globals->get_props() );
    }
#endif
}


// Open and initialize ATC 610x hardware
bool FGATC610x::open() {
    if ( is_enabled() ) {
	SG_LOG( SG_IO, SG_ALERT, "This shouldn't happen, but the channel " 
		<< "is already in use, ignoring" );
	return false;
    }

    SG_LOG( SG_IO, SG_ALERT,
	    "Initializing ATC 610x hardware, please wait ..." );

    // This loads the config parameters generated by "simcal"
    init_config();

    if ( input0_path.str().length() ) {
        input0 = new FGATCInput( 0, input0_path );
        input0->open();
    }
    if ( input1_path.str().length() ) {
        input1 = new FGATCInput( 1, input1_path );
        input1->open();
    }

    set_hz( 30 );		// default to processing requests @ 30Hz
    set_enabled( true );

    board = 0;			// 610x uses a single board number = 0

    snprintf( lock_file, 256, "/proc/atc610x/board%d/lock", board );
    snprintf( lamps_file, 256, "/proc/atc610x/board%d/lamps", board );
    snprintf( radios_file, 256, "/proc/atc610x/board%d/radios", board );
    snprintf( stepper_file, 256, "/proc/atc610x/board%d/steppers", board );

    /////////////////////////////////////////////////////////////////////
    // Open the /proc files
    /////////////////////////////////////////////////////////////////////

    lock_fd = ::open( lock_file, O_RDWR );
    if ( lock_fd == -1 ) {
	SG_LOG( SG_IO, SG_ALERT, "errno = " << errno );
	char msg[256];
	snprintf( msg, 256, "Error opening %s", lock_file );
	perror( msg );
	exit( -1 );
    }

    lamps_fd = ::open( lamps_file, O_WRONLY );
    if ( lamps_fd == -1 ) {
	SG_LOG( SG_IO, SG_ALERT, "errno = " << errno );
	char msg[256];
	snprintf( msg, 256, "Error opening %s", lamps_file );
	perror( msg );
	exit( -1 );
    }

    radios_fd = ::open( radios_file, O_RDWR );
    if ( radios_fd == -1 ) {
	SG_LOG( SG_IO, SG_ALERT, "errno = " << errno );
	char msg[256];
	snprintf( msg, 256, "Error opening %s", radios_file );
	perror( msg );
	exit( -1 );
    }

    stepper_fd = ::open( stepper_file, O_RDWR );
    if ( stepper_fd == -1 ) {
	SG_LOG( SG_IO, SG_ALERT, "errno = " << errno );
	char msg[256];
	snprintf( msg, 256, "Error opening %s", stepper_file );
	perror( msg );
	exit( -1 );
    }


    /////////////////////////////////////////////////////////////////////
    // Home the compass stepper motor
    /////////////////////////////////////////////////////////////////////

    SG_LOG( SG_IO, SG_ALERT,
	    "  - Homing the compass stepper motor" );

    // Lock the hardware, keep trying until we succeed
    while ( ATC610xLock( lock_fd ) <= 0 );

    // Send the stepper home command
    ATC610xSetStepper( stepper_fd, ATC_COMPASS_CH, ATC_STEPPER_HOME );

    // Release the hardware
    ATC610xRelease( lock_fd );

    SG_LOG( SG_IO, SG_ALERT,
	    "  - Waiting for compass to come home." );

    bool home = false;
    int timeout = 900;          // about 30 seconds
    timeout = 0;
    while ( ! home && timeout > 0 ) {
        if ( timeout % 150 == 0 ) {
            SG_LOG( SG_IO, SG_INFO, "waiting for compass = " << timeout );
        } else {
            SG_LOG( SG_IO, SG_DEBUG, "Checking if compass home ..." );
        }

	while ( ATC610xLock( lock_fd ) <= 0 );

	unsigned char result = ATC610xReadStepper( stepper_fd );
	if ( result == 0 ) {
	    home = true;
	}

	ATC610xRelease( lock_fd );

#if defined( _MSC_VER )
	ulMilliSecondSleep(33);
#elif defined (WIN32) && !defined(__CYGWIN__)
        Sleep (33);
#else
	usleep(33);
#endif

        --timeout;
    }

    compass_position = 0.0;

    /////////////////////////////////////////////////////////////////////
    // Blank the radio display
    /////////////////////////////////////////////////////////////////////

    SG_LOG( SG_IO, SG_ALERT,
	    "  - Clearing the radios displays." );

    // Prepair the data
    unsigned char value = 0xff;
    for ( int channel = 0; channel < ATC_RADIO_DISPLAY_BYTES; ++channel ) {
	radio_display_data[channel] = value;
    }

    // Lock the hardware, keep trying until we succeed
    while ( ATC610xLock( lock_fd ) <= 0 );

    // Set radio display
    ATC610xSetRadios( radios_fd, radio_display_data );

    ATC610xRelease( lock_fd );

    /////////////////////////////////////////////////////////////////////
    // Blank the lamps
    /////////////////////////////////////////////////////////////////////

    for ( int i = 0; i < 128; ++i ) {
        ATC610xSetLamp( lamps_fd, i, false );
    }

    /////////////////////////////////////////////////////////////////////
    // Finished initing hardware
    /////////////////////////////////////////////////////////////////////

    SG_LOG( SG_IO, SG_ALERT,
	    "Done initializing ATC 610x hardware." );

    /////////////////////////////////////////////////////////////////////
    // Connect up to property values
    /////////////////////////////////////////////////////////////////////

    mag_compass
        = fgGetNode( "/instrumentation/magnetic-compass/indicated-heading-deg",
                     true );

    dme_min = fgGetNode( "/instrumentation/dme/indicated-time-min", true );
    dme_kt = fgGetNode( "/instrumentation/dme/indicated-ground-speed-kt",
                        true );
    dme_nm = fgGetNode( "/instrumentation/dme/indicated-distance-nm", true );
    dme_in_range = fgGetNode( "/instrumentation/dme/in-range", true );

    adf_bus_power = fgGetNode( "/systems/electrical/outputs/adf", true );
    dme_bus_power = fgGetNode( "/systems/electrical/outputs/dme", true );
    navcom1_bus_power = fgGetNode( "/systems/electrical/outputs/navcom[0]",
                                   true );
    navcom2_bus_power = fgGetNode( "/systems/electrical/outputs/navcom[1]",
                                   true );
    xpdr_bus_power = fgGetNode( "/systems/electrical/outputs/transponder",
                                 true );

    navcom1_power_btn = fgGetNode( "/radios/comm[0]/inputs/power-btn", true );
    navcom2_power_btn = fgGetNode( "/radios/comm[1]/inputs/power-btn", true );

    com1_freq = fgGetNode( "/radios/comm[0]/frequencies/selected-mhz", true );
    com1_stby_freq
	= fgGetNode( "/radios/comm[0]/frequencies/standby-mhz", true );

    com2_freq = fgGetNode( "/radios/comm[1]/frequencies/selected-mhz", true );
    com2_stby_freq
	= fgGetNode( "/radios/comm[1]/frequencies/standby-mhz", true );

    nav1_freq = fgGetNode( "/radios/nav[0]/frequencies/selected-mhz", true );
    nav1_stby_freq
	= fgGetNode( "/radios/nav[0]/frequencies/standby-mhz", true );
    nav1_obs = fgGetNode( "/radios/nav[0]/radials/selected-deg", true );

    nav2_freq = fgGetNode( "/radios/nav[1]/frequencies/selected-mhz", true );
    nav2_stby_freq
	= fgGetNode( "/radios/nav[1]/frequencies/standby-mhz", true );
    nav2_obs = fgGetNode( "/radios/nav[1]/radials/selected-deg", true );

    adf_power_btn
        = fgGetNode( "/instrumentation/kr-87/inputs/power-btn", true );
    adf_vol = fgGetNode( "/instrumentation/kr-87/inputs/volume", true );
    adf_adf_btn = fgGetNode( "/instrumentation/kr-87/inputs/adf-btn", true );
    adf_bfo_btn = fgGetNode( "/instrumentation/kr-87/inputs/bfo-btn", true );
    adf_freq = fgGetNode( "/instrumentation/kr-87/outputs/selected-khz", true );
    adf_stby_freq
        = fgGetNode( "/instrumentation/kr-87/outputs/standby-khz", true );
    adf_stby_mode = fgGetNode( "/instrumentation/kr-87/modes/stby", true );
    adf_timer_mode = fgGetNode( "/instrumentation/kr-87/modes/timer", true );
    adf_count_mode = fgGetNode( "/instrumentation/kr-87/modes/count", true );
    adf_flight_timer
        = fgGetNode( "/instrumentation/kr-87/outputs/flight-timer", true );
    adf_elapsed_timer
        = fgGetNode( "/instrumentation/kr-87/outputs/elapsed-timer",
                                   true );
    adf_ant_ann = fgGetNode( "/instrumentation/kr-87/annunciators/ant", true );
    adf_adf_ann = fgGetNode( "/instrumentation/kr-87/annunciators/adf", true );
    adf_bfo_ann = fgGetNode( "/instrumentation/kr-87/annunciators/bfo", true );
    adf_frq_ann = fgGetNode( "/instrumentation/kr-87/annunciators/frq", true );
    adf_flt_ann = fgGetNode( "/instrumentation/kr-87/annunciators/flt", true );
    adf_et_ann = fgGetNode( "/instrumentation/kr-87/annunciators/et", true );

    inner = fgGetNode( "/radios/marker-beacon/inner", true );
    middle = fgGetNode( "/radios/marker-beacon/middle", true );
    outer = fgGetNode( "/radios/marker-beacon/outer", true );

    xpdr_ident_btn
        = fgGetNode( "/instrumentation/kt-70/inputs/ident-btn", true );
    xpdr_digit1 = fgGetNode( "/instrumentation/kt-70/inputs/digit1", true );
    xpdr_digit2 = fgGetNode( "/instrumentation/kt-70/inputs/digit2", true );
    xpdr_digit3 = fgGetNode( "/instrumentation/kt-70/inputs/digit3", true );
    xpdr_digit4 = fgGetNode( "/instrumentation/kt-70/inputs/digit4", true );
    xpdr_func_knob
        = fgGetNode( "/instrumentation/kt-70/inputs/func-knob", true );
    xpdr_id_code = fgGetNode( "/instrumentation/kt-70/outputs/id-code", true );
    xpdr_flight_level
        = fgGetNode( "/instrumentation/kt-70/outputs/flight-level", true );
    xpdr_fl_ann = fgGetNode( "/instrumentation/kt-70/annunciators/fl", true );
    xpdr_alt_ann = fgGetNode( "/instrumentation/kt-70/annunciators/alt", true );
    xpdr_gnd_ann = fgGetNode( "/instrumentation/kt-70/annunciators/gnd", true );
    xpdr_on_ann = fgGetNode( "/instrumentation/kt-70/annunciators/on", true );
    xpdr_sby_ann = fgGetNode( "/instrumentation/kt-70/annunciators/sby", true );
    xpdr_reply_ann
        = fgGetNode( "/instrumentation/kt-70/annunciators/reply", true );

    ati_bird
      = fgGetNode( "/instrumentation/attitude-indicator/horizon-offset-deg",
		   true );
    alt_press = fgGetNode( "/instrumentation/altimeter/setting-inhg", true );
    adf_hdg = fgGetNode( "/instrumentation/kr-87/inputs/rotation-deg", true );
    hdg_bug = fgGetNode( "/autopilot/settings/heading-bug-deg", true );

    elevator_center = fgGetNode( "/input/atc610x/elevator/center", true );
    elevator_min = fgGetNode( "/input/atc610x/elevator/min", true );
    elevator_max = fgGetNode( "/input/atc610x/elevator/max", true );

    ailerons_center = fgGetNode( "/input/atc610x/ailerons/center", true );
    ailerons_min = fgGetNode( "/input/atc610x/ailerons/min", true );
    ailerons_max = fgGetNode( "/input/atc610x/ailerons/max", true );

    rudder_center = fgGetNode( "/input/atc610x/rudder/center", true );
    rudder_min = fgGetNode( "/input/atc610x/rudder/min", true );
    rudder_max = fgGetNode( "/input/atc610x/rudder/max", true );

    brake_left_min = fgGetNode( "/input/atc610x/brake-left/min", true );
    brake_left_max = fgGetNode( "/input/atc610x/brake-left/max", true );

    brake_right_min = fgGetNode( "/input/atc610x/brake-right/min", true );
    brake_right_max = fgGetNode( "/input/atc610x/brake-right/max", true );

    throttle_min = fgGetNode( "/input/atc610x/throttle/min", true );
    throttle_max = fgGetNode( "/input/atc610x/throttle/max", true );

    mixture_min = fgGetNode( "/input/atc610x/mixture/min", true );
    mixture_max = fgGetNode( "/input/atc610x/mixture/max", true );

    trim_center = fgGetNode( "/input/atc610x/trim/center", true );
    trim_min = fgGetNode( "/input/atc610x/trim/min", true );
    trim_max = fgGetNode( "/input/atc610x/trim/max", true );

    nav1vol_min = fgGetNode( "/input/atc610x/nav1vol/min", true );
    nav1vol_max = fgGetNode( "/input/atc610x/nav1vol/max", true );

    nav2vol_min = fgGetNode( "/input/atc610x/nav2vol/min", true );
    nav2vol_max = fgGetNode( "/input/atc610x/nav2vol/max", true );

    ignore_flight_controls
        = fgGetNode( "/input/atc610x/ignore-flight-controls", true );

    comm1_serviceable
        = fgGetNode( "/instrumentation/comm[0]/serviceable", true );
    comm2_serviceable
        = fgGetNode( "/instrumentation/comm[1]/serviceable", true );
    nav1_serviceable = fgGetNode( "/instrumentation/nav[0]/serviceable", true );
    nav2_serviceable = fgGetNode( "/instrumentation/nav[1]/serviceable", true );
    adf_serviceable = fgGetNode( "/instrumentation/adf/serviceable", true );
    xpdr_serviceable
        = fgGetNode( "/instrumentation/kt-70/inputs/serviceable", true );
    dme_serviceable = fgGetNode( "/instrumentation/dme/serviceable", true );

    dme_selector
        = fgGetNode( "/input/atc-board/radio-switches/raw/dme-switch-position");

    // default to having everything serviceable
    comm1_serviceable->setBoolValue( true );
    comm2_serviceable->setBoolValue( true );
    nav1_serviceable->setBoolValue( true );
    nav2_serviceable->setBoolValue( true );
    adf_serviceable->setBoolValue( true );
    xpdr_serviceable->setBoolValue( true );
    dme_serviceable->setBoolValue( true );

    return true;
}


/////////////////////////////////////////////////////////////////////
// Write the lights
/////////////////////////////////////////////////////////////////////

bool FGATC610x::do_lights() {

    // Marker beacons
    ATC610xSetLamp( lamps_fd, 4, inner->getBoolValue() );
    ATC610xSetLamp( lamps_fd, 5, middle->getBoolValue() );
    ATC610xSetLamp( lamps_fd, 3, outer->getBoolValue() );

    // ADF annunciators
    ATC610xSetLamp( lamps_fd, 11, adf_ant_ann->getBoolValue() ); // ANT
    ATC610xSetLamp( lamps_fd, 12, adf_adf_ann->getBoolValue() ); // ADF
    ATC610xSetLamp( lamps_fd, 13, adf_bfo_ann->getBoolValue() ); // BFO
    ATC610xSetLamp( lamps_fd, 14, adf_frq_ann->getBoolValue() ); // FRQ
    ATC610xSetLamp( lamps_fd, 15, adf_flt_ann->getBoolValue() ); // FLT
    ATC610xSetLamp( lamps_fd, 16, adf_et_ann->getBoolValue() ); // ET

    // Transponder annunciators
    ATC610xSetLamp( lamps_fd, 17, xpdr_fl_ann->getBoolValue() ); // FL
    ATC610xSetLamp( lamps_fd, 18, xpdr_alt_ann->getBoolValue() ); // ALT
    ATC610xSetLamp( lamps_fd, 19, xpdr_gnd_ann->getBoolValue() ); // GND
    ATC610xSetLamp( lamps_fd, 20, xpdr_on_ann->getBoolValue() ); // ON
    ATC610xSetLamp( lamps_fd, 21, xpdr_sby_ann->getBoolValue() ); // SBY
    ATC610xSetLamp( lamps_fd, 22, xpdr_reply_ann->getBoolValue() ); // R

    return true;
}


/////////////////////////////////////////////////////////////////////
// Update the radio display 
/////////////////////////////////////////////////////////////////////

bool FGATC610x::do_radio_display() {

    char digits[10];
    int i;

    if ( dme_has_power() && dme_serviceable->getBoolValue() ) {
        if ( dme_in_range->getBoolValue() ) {
            // DME minutes
            float minutes = dme_min->getFloatValue();
            if ( minutes > 999 ) {
                minutes = 999.0;
            }
            snprintf(digits, 7, "%03.0f", minutes);
            for ( i = 0; i < 6; ++i ) {
                digits[i] -= '0';
            }
            radio_display_data[0] = digits[1] << 4 | digits[2];
            radio_display_data[1] = 0xf0 | digits[0];
	
            // DME knots
            float knots = dme_kt->getFloatValue();
            if ( knots > 999 ) {
                knots = 999.0;
            }
            snprintf(digits, 7, "%03.0f", knots);
            for ( i = 0; i < 6; ++i ) {
                digits[i] -= '0';
            }
            radio_display_data[2] = digits[1] << 4 | digits[2];
            radio_display_data[3] = 0xf0 | digits[0];

            // DME distance (nm)
            float nm = dme_nm->getFloatValue();
            if ( nm > 99 ) {
                nm = 99.0;
            }
            snprintf(digits, 7, "%04.1f", nm);
            for ( i = 0; i < 6; ++i ) {
                digits[i] -= '0';
            }
            radio_display_data[4] = digits[1] << 4 | digits[3];
            radio_display_data[5] = 0x00 | digits[0];
            // the 0x00 in the upper nibble of the 6th byte of each
            // display turns on the decimal point
        } else {
            // out of range
            radio_display_data[0] = 0xbb;
            radio_display_data[1] = 0xfb;
            radio_display_data[2] = 0xbb;
            radio_display_data[3] = 0xfb;
            radio_display_data[4] = 0xbb;
            radio_display_data[5] = 0x0b;
        }
    } else {
	// blank dem display
	for ( i = 0; i < 6; ++i ) {
	    radio_display_data[i] = 0xff;
	}
    }

    if ( navcom1_has_power() && comm1_serviceable->getBoolValue() ) {
        // Com1 standby frequency
        float com1_stby = com1_stby_freq->getFloatValue();
        if ( fabs(com1_stby) > 999.99 ) {
            com1_stby = 0.0;
        }
        snprintf(digits, 7, "%06.3f", com1_stby);
        for ( i = 0; i < 6; ++i ) {
            digits[i] -= '0';
        }
        radio_display_data[6] = digits[4] << 4 | digits[5];
        radio_display_data[7] = digits[1] << 4 | digits[2];
        radio_display_data[8] = 0xf0 | digits[0];

        // Com1 in use frequency
        float com1 = com1_freq->getFloatValue();
        if ( fabs(com1) > 999.99 ) {
            com1 = 0.0;
        }
        snprintf(digits, 7, "%06.3f", com1);
        for ( i = 0; i < 6; ++i ) {
            digits[i] -= '0';
        }
        radio_display_data[9] = digits[4] << 4 | digits[5];
        radio_display_data[10] = digits[1] << 4 | digits[2];
        radio_display_data[11] = 0x00 | digits[0];
        // the 0x00 in the upper nibble of the 6th byte of each display
        // turns on the decimal point
    } else {
        radio_display_data[6] = 0xff;
        radio_display_data[7] = 0xff;
        radio_display_data[8] = 0xff;
        radio_display_data[9] = 0xff;
        radio_display_data[10] = 0xff;
        radio_display_data[11] = 0xff;
    }

    if ( navcom2_has_power() && comm2_serviceable->getBoolValue() ) {
        // Com2 standby frequency
        float com2_stby = com2_stby_freq->getFloatValue();
        if ( fabs(com2_stby) > 999.99 ) {
            com2_stby = 0.0;
        }
        snprintf(digits, 7, "%06.3f", com2_stby);
        for ( i = 0; i < 6; ++i ) {
            digits[i] -= '0';
        }
        radio_display_data[18] = digits[4] << 4 | digits[5];
        radio_display_data[19] = digits[1] << 4 | digits[2];
        radio_display_data[20] = 0xf0 | digits[0];

        // Com2 in use frequency
        float com2 = com2_freq->getFloatValue();
        if ( fabs(com2) > 999.99 ) {
	com2 = 0.0;
        }
        snprintf(digits, 7, "%06.3f", com2);
        for ( i = 0; i < 6; ++i ) {
            digits[i] -= '0';
        }
        radio_display_data[21] = digits[4] << 4 | digits[5];
        radio_display_data[22] = digits[1] << 4 | digits[2];
        radio_display_data[23] = 0x00 | digits[0];
        // the 0x00 in the upper nibble of the 6th byte of each display
        // turns on the decimal point
    } else {
        radio_display_data[18] = 0xff;
        radio_display_data[19] = 0xff;
        radio_display_data[20] = 0xff;
        radio_display_data[21] = 0xff;
        radio_display_data[22] = 0xff;
        radio_display_data[23] = 0xff;
    }

    if ( navcom1_has_power() && nav1_serviceable->getBoolValue() ) {
        // Nav1 standby frequency
        float nav1_stby = nav1_stby_freq->getFloatValue();
        if ( fabs(nav1_stby) > 999.99 ) {
	nav1_stby = 0.0;
        }
        snprintf(digits, 7, "%06.2f", nav1_stby);
        for ( i = 0; i < 6; ++i ) {
            digits[i] -= '0';
        }
        radio_display_data[12] = digits[4] << 4 | digits[5];
        radio_display_data[13] = digits[1] << 4 | digits[2];
        radio_display_data[14] = 0xf0 | digits[0];

        // Nav1 in use frequency
        float nav1 = nav1_freq->getFloatValue();
        if ( fabs(nav1) > 999.99 ) {
            nav1 = 0.0;
        }
        snprintf(digits, 7, "%06.2f", nav1);
        for ( i = 0; i < 6; ++i ) {
            digits[i] -= '0';
        }
        radio_display_data[15] = digits[4] << 4 | digits[5];
        radio_display_data[16] = digits[1] << 4 | digits[2];
        radio_display_data[17] = 0x00 | digits[0];
        // the 0x00 in the upper nibble of the 6th byte of each display
        // turns on the decimal point
    } else {
        radio_display_data[12] = 0xff;
        radio_display_data[13] = 0xff;
        radio_display_data[14] = 0xff;
        radio_display_data[15] = 0xff;
        radio_display_data[16] = 0xff;
        radio_display_data[17] = 0xff;
    }

    if ( navcom2_has_power() && nav2_serviceable->getBoolValue() ) {
        // Nav2 standby frequency
        float nav2_stby = nav2_stby_freq->getFloatValue();
        if ( fabs(nav2_stby) > 999.99 ) {
            nav2_stby = 0.0;
        }
        snprintf(digits, 7, "%06.2f", nav2_stby);
        for ( i = 0; i < 6; ++i ) {
            digits[i] -= '0';
        }
        radio_display_data[24] = digits[4] << 4 | digits[5];
        radio_display_data[25] = digits[1] << 4 | digits[2];
        radio_display_data[26] = 0xf0 | digits[0];

        // Nav2 in use frequency
        float nav2 = nav2_freq->getFloatValue();
        if ( fabs(nav2) > 999.99 ) {
            nav2 = 0.0;
        }
        snprintf(digits, 7, "%06.2f", nav2);
        for ( i = 0; i < 6; ++i ) {
            digits[i] -= '0';
        }
        radio_display_data[27] = digits[4] << 4 | digits[5];
        radio_display_data[28] = digits[1] << 4 | digits[2];
        radio_display_data[29] = 0x00 | digits[0];
        // the 0x00 in the upper nibble of the 6th byte of each display
        // turns on the decimal point
    } else {
        radio_display_data[24] = 0xff;
        radio_display_data[25] = 0xff;
        radio_display_data[26] = 0xff;
        radio_display_data[27] = 0xff;
        radio_display_data[28] = 0xff;
        radio_display_data[29] = 0xff;
    }

    // ADF standby frequency / timer
    if ( adf_has_power() && adf_serviceable->getBoolValue() ) {
        if ( adf_stby_mode->getIntValue() == 0 ) {
            // frequency
            float adf_stby = adf_stby_freq->getFloatValue();
            if ( fabs(adf_stby) > 1799 ) {
                adf_stby = 1799;
            }
            snprintf(digits, 7, "%04.0f", adf_stby);
            for ( i = 0; i < 6; ++i ) {
                digits[i] -= '0';
            }
            radio_display_data[30] = digits[3] << 4 | 0x0f;
            radio_display_data[31] = digits[1] << 4 | digits[2];
            if ( digits[0] == 0 ) {
                radio_display_data[32] = 0xff;
            } else {
                radio_display_data[32] = 0xf0 | digits[0];
            }
        } else {
            // timer
            double time;
            int hours, min, sec;
            if ( adf_timer_mode->getIntValue() == 0 ) {
                time = adf_flight_timer->getDoubleValue();
            } else {
                time = adf_elapsed_timer->getDoubleValue();
            }
            // cout << time << endl;
            hours = (int)(time / 3600.0);
            time -= hours * 3600.00;
            min = (int)(time / 60.0);
            time -= min * 60.0;
            sec = (int)time;
            int big, little;
            if ( hours > 0 ) {
                big = hours;
                if ( big > 99 ) {
                    big = 99;
                }
                little = min;
            } else {
                big = min;
                little = sec;
            }
            if ( big > 99 ) {
                big = 99;
            }
            // cout << big << ":" << little << endl;
            snprintf(digits, 7, "%02d%02d", big, little);
            for ( i = 0; i < 6; ++i ) {
                digits[i] -= '0';
            }
            radio_display_data[30] = digits[2] << 4 | digits[3];
            radio_display_data[31] = digits[0] << 4 | digits[1];
            radio_display_data[32] = 0xff;
        }

        // ADF in use frequency
        float adf = adf_freq->getFloatValue();
        if ( fabs(adf) > 1799 ) {
            adf = 1799;
        }
        snprintf(digits, 7, "%04.0f", adf);
        for ( i = 0; i < 6; ++i ) {
            digits[i] -= '0';
        }
        radio_display_data[33] = digits[2] << 4 | digits[3];
        if ( digits[0] == 0 ) {
            radio_display_data[34] = 0xf0 | digits[1];
        } else {
            radio_display_data[34] = digits[0] << 4 | digits[1];
        }
        if ( adf_stby_mode->getIntValue() == 0 ) {
	  radio_display_data[35] = 0xff;
	} else {
	  radio_display_data[35] = 0x0f;
	}
    } else {
        radio_display_data[30] = 0xff;
        radio_display_data[31] = 0xff;
        radio_display_data[32] = 0xff;
        radio_display_data[33] = 0xff;
        radio_display_data[34] = 0xff;
        radio_display_data[35] = 0xff;
    }
    
    // Transponder code and flight level
    if ( xpdr_has_power() && xpdr_serviceable->getBoolValue() ) {
        if ( xpdr_func_knob->getIntValue() == 2 ) {
            // test mode
            radio_display_data[36] = 8 << 4 | 8;
            radio_display_data[37] = 8 << 4 | 8;
            radio_display_data[38] = 0xff;
            radio_display_data[39] = 8 << 4 | 0x0f;
            radio_display_data[40] = 8 << 4 | 8;
        } else {
            // other on modes
            int id_code = xpdr_id_code->getIntValue();
            int place = 1000;
            for ( i = 0; i < 4; ++i ) {
                digits[i] = id_code / place;
                id_code -= digits[i] * place;
                place /= 10;
            }
            radio_display_data[36] = digits[2] << 4 | digits[3];
            radio_display_data[37] = digits[0] << 4 | digits[1];
            radio_display_data[38] = 0xff;

            if ( xpdr_func_knob->getIntValue() == 3 ||
                 xpdr_func_knob->getIntValue() == 5 )
            {
                // do flight level display
                snprintf(digits, 7, "%03d", xpdr_flight_level->getIntValue() );
                for ( i = 0; i < 6; ++i ) {
                    digits[i] -= '0';
                }
                radio_display_data[39] = digits[2] << 4 | 0x0f;
                radio_display_data[40] = digits[0] << 4 | digits[1];
            } else {
                // blank flight level display
                radio_display_data[39] = 0xff;
                radio_display_data[40] = 0xff;
            }
        }
    } else {
        // off
        radio_display_data[36] = 0xff;
        radio_display_data[37] = 0xff;
        radio_display_data[38] = 0xff;
        radio_display_data[39] = 0xff;
        radio_display_data[40] = 0xff;
    }

    ATC610xSetRadios( radios_fd, radio_display_data );

    return true;
}


/////////////////////////////////////////////////////////////////////
// Drive the stepper motors
/////////////////////////////////////////////////////////////////////

bool FGATC610x::do_steppers() {
    float diff = mag_compass->getFloatValue() - compass_position;
    while ( diff < -180.0 ) { diff += 360.0; }
    while ( diff >  180.0 ) { diff -= 360.0; }

    int steps = (int)(diff * 4);
    // cout << "steps = " << steps << endl;
    if ( steps > 4 ) { steps = 4; }
    if ( steps < -4 ) { steps = -4; }

    if ( abs(steps) > 0 ) {
	unsigned char cmd = 0x80;	// stepper command
	if ( steps > 0 ) {
	    cmd |= 0x20;		// go up
	} else {
	    cmd |= 0x00;		// go down
	}
	cmd |= abs(steps);

	// sync compass_position with hardware position
	compass_position += (float)steps / 4.0;

	ATC610xSetStepper( stepper_fd, ATC_COMPASS_CH, cmd );
    }

    return true;
}


bool FGATC610x::process() {
    
    // Lock the hardware, skip if it's not ready yet
    if ( ATC610xLock( lock_fd ) > 0 ) {

        // process the ATC inputs
        if ( input0 != NULL ) {
            input0->process();
        }
        if ( input1 != NULL ) {
            input1->process();
        }

        // run our custom nasal script.  This is a layer above the raw
        // hardware inputs.  It handles situations where there isn't a
        // direct 1-1 linear mapping between ATC functionality and FG
        // functionality, and handles situations where FG expects more
        // functionality from the interface than the ATC hardware can
        // directly provide.

        FGNasalSys *n = (FGNasalSys*)globals->get_subsystem("nasal");
        bool result = n->parseAndRun( "atcsim.do_hardware()" );
        if ( !result ) {
            SG_LOG( SG_GENERAL, SG_ALERT,
                    "do_atcflightsim_hardware() failed!" );
        }

	do_lights();
	do_radio_display();
	do_steppers();
	
	ATC610xRelease( lock_fd );

	return true;
    } else {
	return false;
    }
}


bool FGATC610x::close() {

    return true;
}