1
0
Fork 0
flightgear/src/Instrumentation/transponder.cxx
Richard Senior ef6af467ed Add airspeed and ground bit to MP protocol for Mode-S transponders
Ground-bit is set manually (via the transponder GND knob position) or
automatically using a property referenced in instrumentation.xml.

Aircraft will only transmit these new properties when using the
multiplayer v2 protocol.
2017-06-27 16:04:30 +01:00

351 lines
12 KiB
C++

// transponder.cxx -- class to implement a transponder
//
// Written by Roy Vegard Ovesen, started September 2004.
//
// Copyright (C) 2004 Roy Vegard Ovesen - rvovesen@tiscali.no
// Copyright (C) 2013 Clement de l'Hamaide - clemaez@hotmail.fr
//
// 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
//
// Example invocation, in the instrumentation.xml file:
// <transponder>
// <name>encoder</name>
// <number>0</number>
// <mode>2</mode> // Mode A = 0, Mode C = 1, Mode S = 2
// <auto-ground>...</auto-ground>
// <airspeed-path>...</airspeed-path>
// </altimeter>
//
// Mode-S transponders (configured with mode = 2) can transmit a ground bit to
// indicate ground operation. If auto-ground is not defined, the ground bit is
// switched manually by setting the transponder knob to GND. If auto-ground is
// defined, the transponder simulates automatic switching of the ground bit
// using the value of the property defined in auto-ground.
//
// For a squat switch, use "/gear/gear/wow". For automatic switching based on
// airspeed, use a property rule to make a new boolean property that indicates,
// for example, airspeed < 80, and reference your new property in auto-ground.
//
// Note that Mode-A and Mode-C transponders do not transmit a ground bit, even
// if the transponder knob is set to the GND position.
//
// Mode-S transponders also transmit indicated airspeed. The default source of
// this is /instrumentation/airspeed-indicator/indicated-speed-kt but this can be
// changed by setting the airspeed-path property as shown above.
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include "transponder.hxx"
#include <simgear/compiler.h>
#include <simgear/sg_inlines.h>
#include <simgear/debug/logstream.hxx>
#include <Main/fg_props.hxx>
#include <cstdio>
using std::string;
const double IDENT_TIMEOUT = 18.0; // 18 seconds
const int INVALID_ALTITUDE = -9999;
const int INVALID_AIRSPEED = -9999;
const int INVALID_ID = -9999;
Transponder::Transponder(SGPropertyNode *node)
:
_identMode(false),
_name(node->getStringValue("name", "transponder")),
_num(node->getIntValue("number", 0)),
_mode((Mode) node->getIntValue("mode", 1)),
_listener_active(0)
{
_requiredBusVolts = node->getDoubleValue("bus-volts", 8.0);
_altitudeSourcePath = node->getStringValue("encoder-path", "/instrumentation/altimeter");
_autoGroundPath = node->getStringValue("auto-ground");
_airspeedSourcePath = node->getStringValue("airspeed-path", "/instrumentation/airspeed-indicator/indicated-speed-kt");
_kt70Compat = node->getBoolValue("kt70-compatibility", false);
}
Transponder::~Transponder()
{
}
void Transponder::init()
{
SGPropertyNode *node = fgGetNode("/instrumentation/" + _name, _num, true );
// Inputs
_busPower_node = fgGetNode("/systems/electrical/outputs/transponder", true);
_pressureAltitude_node = fgGetNode(_altitudeSourcePath, true);
_autoGround_node = fgGetNode(_autoGroundPath, true);
_airspeedIndicator_node = fgGetNode(_airspeedSourcePath, true);
SGPropertyNode *in_node = node->getChild("inputs", 0, true);
for (int i=0; i<4;++i) {
_digit_node[i] = in_node->getChild("digit", i, true);
_digit_node[i]->addChangeListener(this);
}
_knob_node = in_node->getChild("knob-mode", 0, true);
if (!_knob_node->hasValue()) {
_knob = KNOB_ON;
// default to, if aircraft wants to start dark, it can do this
// in its -set.xml
_knob_node->setIntValue(_knob);
} else {
_knob = static_cast<KnobPosition>(_knob_node->getIntValue());
}
_knob_node->addChangeListener(this);
_mode_node = in_node->getChild("mode", 0, true);
_mode_node->setIntValue(_mode);
_mode_node->addChangeListener(this);
_identBtn_node = in_node->getChild("ident-btn", 0, true);
_identBtn_node->setBoolValue(false);
_identBtn_node->addChangeListener(this);
_serviceable_node = node->getChild("serviceable", 0, true);
_serviceable_node->setBoolValue(true);
_idCode_node = node->getChild("id-code", 0, true);
_idCode_node->addChangeListener(this);
// set default, but don't overwrite value from defaults.xml or -set.xml
if (!_idCode_node->hasValue()) {
_idCode_node->setIntValue(1200);
}
// Outputs
_altitude_node = node->getChild("altitude", 0, true);
_altitudeValid_node = node->getChild("altitude-valid", 0, true);
_ident_node = node->getChild("ident", 0, true);
_transmittedId_node = node->getChild("transmitted-id", 0, true);
_ground_node = node->getChild("ground-bit", 0, true);
_airspeed_node = node->getChild("airspeed-kt", 0, true);
if (_kt70Compat) {
// alias the properties through
SGPropertyNode_ptr output = node->getChild("outputs", 0, true);
output->getChild("flight-level", 0, true)->alias(_altitude_node);
output->getChild("id-code", 0, true)->alias(_idCode_node);
in_node->getChild("func-knob", 0, true)->alias(_knob_node);
}
}
void Transponder::bind()
{
if (_kt70Compat) {
SGPropertyNode *node = fgGetNode("/instrumentation/" + _name, _num, true );
_tiedProperties.setRoot(node);
_tiedProperties.Tie("annunciators/fl", this,
&Transponder::getFLAnnunciator );
_tiedProperties.Tie("annunciators/alt", this,
&Transponder::getAltAnnunciator );
_tiedProperties.Tie("annunciators/gnd", this,
&Transponder::getGroundAnnuciator );
_tiedProperties.Tie("annunciators/on", this,
&Transponder::getOnAnnunciator );
_tiedProperties.Tie("annunciators/sby", this,
&Transponder::getStandbyAnnunciator );
_tiedProperties.Tie("annunciators/reply", this,
&Transponder::getReplyAnnunciator );
} // of kt70 backwards compatibility
}
void Transponder::unbind()
{
_tiedProperties.Untie();
}
void Transponder::update(double dt)
{
if (has_power() && _serviceable_node->getBoolValue())
{
// Mode C & S send also altitude
Mode effectiveMode = (_knob == KNOB_ALT || _knob == KNOB_GROUND) ? _mode : MODE_A;
SGPropertyNode* altitudeSource = NULL;
switch (effectiveMode) {
case MODE_C:
altitudeSource = _pressureAltitude_node->getChild("mode-c-alt-ft");
break;
case MODE_S:
altitudeSource = _pressureAltitude_node->getChild("mode-s-alt-ft");
break;
default:
break;
}
int alt = INVALID_ALTITUDE;
if (effectiveMode != MODE_A) {
if (altitudeSource) {
alt = altitudeSource->getIntValue();
} else {
// warn if altitude input is misconfigured
SG_LOG(SG_INSTR, SG_INFO, "transponder altitude input for mode " << _mode << " is missing");
}
}
_altitude_node->setIntValue(alt);
_altitudeValid_node->setBoolValue(alt != INVALID_ALTITUDE);
if ( _identMode ) {
_identTime += dt;
if ( _identTime > IDENT_TIMEOUT ) {
// reset ident mode
_ident_node->setBoolValue(false);
_identMode = false;
}
}
if (_knob >= KNOB_GROUND) {
_transmittedId_node->setIntValue(_idCode_node->getIntValue());
} else {
_transmittedId_node->setIntValue(INVALID_ID);
}
if (_mode == MODE_S && _knob >= KNOB_GROUND) {
if (_autoGround_node->hasValue()) {
// Automatic ground bit based on the auto-ground property
_ground_node->setBoolValue(_autoGround_node->getBoolValue());
} else {
// Manual ground bit based on the transponder knob
_ground_node->setBoolValue(_knob == KNOB_GROUND);
}
} else {
_ground_node->setBoolValue(false);
}
if (_mode == MODE_S && _knob >= KNOB_GROUND && _airspeedIndicator_node->hasValue()) {
_airspeed_node->setIntValue(_airspeedIndicator_node->getIntValue());
} else {
_airspeed_node->setIntValue(INVALID_AIRSPEED);
}
}
else
{
_altitude_node->setIntValue(INVALID_ALTITUDE);
_altitudeValid_node->setBoolValue(false);
_ident_node->setBoolValue(false);
_ground_node->setBoolValue(false);
_airspeed_node->setIntValue(INVALID_AIRSPEED);
_transmittedId_node->setIntValue(INVALID_ID);
}
}
static int powersOf10[4] = {1, 10, 100, 1000};
static int extractCodeDigit(int code, int index)
{
return (code / powersOf10[index]) % 10;
}
static int modifyCodeDigit(int code, int index, int digitValue)
{
assert(digitValue >= 0 && digitValue < 8);
int p = powersOf10[index];
int codeWithoutDigit = code - (extractCodeDigit(code, index) * p);
return codeWithoutDigit + (digitValue * p);
}
void Transponder::valueChanged(SGPropertyNode *prop)
{
// Ident button pressed
if (prop == _identBtn_node) {
if (prop->getBoolValue()) {
_identTime = 0.0;
_ident_node->setBoolValue(true);
_identMode = true;
} else {
// don't cancel state on release
}
return;
}
if (prop == _mode_node) {
_mode = static_cast<Mode>(prop->getIntValue());
return;
}
if (prop == _knob_node) {
_knob = static_cast<KnobPosition>(prop->getIntValue());
return;
}
if (_listener_active)
return;
_listener_active++;
if (prop == _idCode_node) {
// keep the digits in-sync
for (int i=0; i<4; ++i) {
_digit_node[i]->setIntValue(extractCodeDigit(prop->getIntValue(), i));
}
} else {
// digit node
int index = prop->getIndex();
int digitValue = prop->getIntValue();
SG_CLAMP_RANGE<int>(digitValue, 0, 7);
_idCode_node->setIntValue(modifyCodeDigit(_idCode_node->getIntValue(), index, digitValue));
prop->setIntValue(digitValue);
}
_listener_active--;
}
bool Transponder::has_power() const
{
return (_knob_node->getIntValue() > KNOB_STANDBY) && (_busPower_node->getDoubleValue() > _requiredBusVolts);
}
bool Transponder::getFLAnnunciator() const
{
return (_knob == KNOB_ALT) || (_knob == KNOB_GROUND) || (_knob == KNOB_TEST);
}
bool Transponder::getAltAnnunciator() const
{
return (_knob == KNOB_ALT) || (_knob == KNOB_TEST);
}
bool Transponder::getGroundAnnuciator() const
{
return (_knob == KNOB_GROUND) || (_knob == KNOB_TEST);
}
bool Transponder::getOnAnnunciator() const
{
return (_knob == KNOB_ON) || (_knob == KNOB_TEST);
}
bool Transponder::getStandbyAnnunciator() const
{
return (_knob == KNOB_STANDBY) || (_knob == KNOB_TEST);
}
bool Transponder::getReplyAnnunciator() const
{
return _identMode || (_knob == KNOB_TEST);
}