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A relatively cost efficient way of learning the control of R/C models is the use of simulators. When you primarily want to practise with your original R/C transmitter with the chosen simulator, it is necessary to connect the transmitter to the PC. The type of the transmitter, the type of the simulator, and the available connections on the PC also determines your choice of the interface. In the following, I shortly describe the available interfaces in general, and I detail my interfaces in particular.

The generally available solutions:

The input device has to be accepted by the chosen simulator:

• the wast majority of simulators accepts the system's game controllers, ( standard joystick on the game port, human interface device class joysticks on the USB port, and with device dependent drivers: different controllers on different ports ).
• there are simulators supporting special hardware input devices, designed for the given simulator only: depending on the device these can be more or less system independent, some examples are: the commercially available Aero Fly simulator with a unique interface, the freely available FMS with two solutions, and crrcsim with even more solutions.

The input device has to be connected to the PC, to do this you have to have a freely available port for this:

• GAME port: widely used input port for game controllers, these analog devices may be configured for the system as standard joysticks, making them available not only for simulators, but for games, and other applications too. The game port is common in PC-s, usually as part of the sound subsystem, but USB begins to take it's role over.
• USB port: it accepts wide range of devices, the port protocol is quite complex from the developers side, and quite simple from the user side. If the device fulfills requirements of a subset of the standard ( h.i.d. class joystick ) then the system also recognizes it as a joystick, and is also available not only for simulators. Due to the complexity of development, and the high needs of resources, the price is usually relatively high.
• LPT port: these devices are usually supported only by a given simulator, and are not available system widely. FMS accepts it's own LPT port interface, signalling on the IRQ line of the port, and crrcsim accepts it's own microcontroller based LPT interface.
• COM port: there are some game controllers ( for example SpaceOrb from SpaceTech ) using this port with it's own device driver. Where the driver is available, the controller works system widely. And there are some different solutions for the COM port: FMS has two types of interfaces for COM port: one of them ( IRQ line solution, similar to the LPT version ) available only under Win9x, but the more sophisticated MCU based solution ( FMS-PIC ) is not restricted to Win9x. Some developers on the net nowadays writes a driver for the FMS-PIC that makes it available as a game controller system widely ( PPJoy, PPJoyCom ). A have written a small modification for crrcsim, to accept this FMS-PIC controller under Linux, the source code available on request, or if somebody offers a web or ftp place then it will be available for free download.
• Audio line input: these devices usually requires drivers, what makes it available for game control. These drivers are not perfect, yet, and are system dependent. Other drawback is: to process an audio signal to get the desired game controller resolution, requires a lot of system resources, and the resulting position output is not as accurate as desired. To connect a transmitter to the audio line input port you have to match the PPM signal level to the line input. There are developments to write a joystick driver for it ( SmartPropo ), and crrcsim handles the audio input by default.

All the above interfaces usually connects to the transmitter's trainer connector. This requires some compatibility from the transmitter ( type of modulation ):

• PPM: old fashioned way of remote control, the most of the transmitters on the market, supports this type of modulation. The timing differences are covered by well behaving interfaces, except some electronics made available for the public in an early development state.
• PCM: a recent type of modulation, that carries a lot of additional features, but different brands always sticks to it's own code formats, this makes different transmission systems incompatible. A rare exception if you find an interface supporting at least one type of PCM modulation. But: those who owns a PCM transmitter probably don"t need another one, the wast majority of the PCM transmitters can be switched into PPM mode from the transmitter menu.

Interfaces available form me:

After this, if somebody needs an interface cable, may search the net, or choose one from the three currently available type from me:

• FMS-IRQ interface: this is accepted only by the FMS simulator, on a free 9 pin COM port of the PC. Further requirement: FMS supports this type of connection only on Windows 95/98/98se. The recently used ( Windows NT based ) 2000 and XP o.s.-es doesn't let the simulator take such a control over the PC as it would be required. The support for this interface was included in the simulator relatively early, this means, it is available with older versions of FMS too. The electronics is relatively simple, contains only two transistors and a few passive components, power is supplied to it through the COM port's signal lines. The interface available from me is built partially from SMD components, into the 9 pin COM port connector's case, the price is 3400 Ft in Hungary, 17 EUR abroad, further details below.

• FMS-PIC interface: fully supported by FMS simulator from version 2.0 Beta 7, supported by PPJoyCom ( PPJoy package freely available on simtel.net ) joystick driver ( currently working only under Xp ), and under Linux, with my source code modification by crrcsim. Connects to a free 9 pin COM port of the PC. The connection is supported by FMS under Win 95/98/98se/2000/XP. The interface electronics is built into the COM port connector's enclosure, contains a flash MCU, partially built from SMD components, sends measured PPM channel data to the PC with a standard 19200 baud serial communication, and acquires it's supply power from the COM port's data lines. The price is 5400 Ft in Hungary, 24 EUR abroad, further details below.

• RC-GAME interface: emulates a standard joystick, and may be used with all the programs, what is configurable to be driven by a standard joystick. The PPM output of the R/C transmitter is measured by a MCU, and 4 digital potentiometers ( 100 kOhm ) are adjusted according to the input signal and setup parameters, to drive the game port with a true resistance output. A push button on the enclosure is available to be used as button for the game port, to support calibration under Win.. These button is also useful to walk through the interface's own calibration menu. With this interface calibration option you can setup the interface to match your transmitter, and you can change the channel arrangement and direction on a channel by channel basis. The interface is compatible with all the o.s. -es that supports standard joysticks. On Win.. it is configurable as a 4 axes, 1 button joystick ( but due to the fact that it uses the button feedback lights to display the internal state during calibration, it is recommended to be configured as a 4 axes 4 button controller ). The interface is compatible with not only game ports based on the old NE558 circuit ( originating from XT times ) but with A/D converter based solutions found on some notebooks and Game/USB adapters. The interface cable is built up form two sub-parts: from the cable, this contains the transmitter dependent connections, but no electronics, and the interface electronics itself. The interface electronics is built into a SUB-D 15/15 converter enclosure, and may be connected directly to the game port connector. The setup instructions for the interface is available here but currently only in hungarian ( english version on request ). The price is 7900 Ft in Hungary, 40 EUR abroad, further details below.

The pictures above are only illustrations, the actual outfit depends on the available parts, but I try to hold the quality as possible. The cord is 2 m long, the transmitter connector is chosen based on negotiation. The price contains V.A.T. and postage costs world wide, but doesn't contains the money transfer fee to me. For international customers only pre payment is the currently only option via bank transfer ( if you would like to pay via PayPal let me know ). The interfaces are shipped with a 1 month money back guarantee ( two month for international orders ) and a one year normal guarantee. The guarantee is limited: you have to cover the costs of the transfer of the device to me. All the international orders are shipped with an english version of the setup instructions.

From the above selection I suggest the FMS-PIC interface, if the listed restrictions are not scaring you away.

R/C transmitters

These interface electronics, connects to the R/C transmitters buddy ( trainer ) socket, and needs PPM ( Pulse Position Modulated ) signals. From brand to brand, or at some manufacturers from type to type, the trainer connector pinout, signal level, and features are changing. A good collection of available transmitter pinouts are described at http://users.belgacom.net/TX2TX/. Further requirements to set up your transmitter for usage with simulators are: When you use the transmitter with a simulator, you transmitter can't be powered through the trainer cord from the other transmitter, because during simulation there is not another transmitter ( this is applicable to some Futaba transmitters ). The transmitter has to be turned on, but the RF ( Radio Frequency ) output has to be turned off, to avoid unnecessary rf output, and unnecessarily high discharge rate of the batteries. This may be achieved on some transmitters ( usually equipped with DIN trainer connector ) with placing a shorting wire between specific points of the trainer connector plug, on some featured transmitter the RF circuitry may be turned off from software, but the most general solution is to pull out the quartz crystal from the transmitter.

Some proven solution:

• HITEC Laser 4, Flash 5, Eclipse 7 equipped with 6 pole DIN plug, Hitec pinout, rf turned off by a shorting wire placed in the plug.
• FUTABA FX-18 2.5 mm Phone plug, rf may be turned off by pulling out the crystal.
• FUTABA SkySport 4 equipped with 6 pole DIN plug, Futaba pinout, shorting wire placed in the plug has no effect, rf may be turned off by pulling out the crystal.
• MULTIPLEX Europa equipped with 5 pole DIN plug, Multiplex pinout, rf may be turned off by pulling out the crystal.
• MULTIPLEX Royal Evo equipped with 7 pole DIN plug, extended Multiplex pinout, rf is turned out from software.
• FUTABA with sqare connector this type of connector is not available in Hungary, I fit these orders with a "do it yourself" plug, this means I solder two jumper pins to the cable, what can be plugged into the transmitter through a separating layer ( to protect the transmitter from glue ), and the pins glued carefully together with for example a fast epoxy glue.

The most uniform solution is from Hitec: all the known transmitters are equipped with the same connector, and the same pinout. The most versatile manufacturer is Futaba, who may use different connectors on different transmitter types, and may use same connectors with different pinout, and most recently uses non standard 6 pin square connectors.

Some interesting links:
fms - free flying model simulator.
fms hungarian menu - menu and some instructions in hungarian.
fms forum - discussion group for fms.
rcmodell fórum - hungarian discussion groups related to modeling.
rc-sim - simulator and interface electronics comparisons, links.
crrcsim - free simulator for linux.

Send comments and request in email, or in the evenings ( 19:30 - 21:00 CET ) on phone: +36-29-351-678.