245 lines
13 KiB
Markdown
Executable File
245 lines
13 KiB
Markdown
Executable File
# Necroware's GamePort Adapter
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Many people from the retro community still have their beloved joysticks and
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gamepads from the early days. These devices often live their lives somewhere in
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the dark corners of our basements and we don't dare to throw them away, because
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of nostalgic reasons. They remind us so much of our childhoods, where we played
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our Wing Commanders, X-Wings, Descents and many other games. These old joysticks
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were all made to be connected to the game port, usually on a sound card. But
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by the end of 90's and beginning of 2000's game ports vanished from our
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computers and were replaced by USB and our old joysticks disappeared into the
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past. Today not everybody has a full retro PC and many people are using their
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modern computer with DOSBox to play the old games, sometimes with a modern
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USB joystick. But wouldn't it be great to play the old games with the same
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joystick which we used back then? And this is where this adapter comes into
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play. It can be used to connect gameport joysticks to a USB port.
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GamePort Adapter Videos:
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* [Part 1: Introduction](https://youtu.be/tSJLgCD8jeM)
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* [Part 2: Updates](https://youtu.be/947DewHwbsE)
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## How does it work?
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The adapter is built around Arduino Pro Micro, which uses the same ATmega32U4
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microcontroller as Leonardo. This microcontroller has built-in USB HID
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capabilities and can be used to build HID input devices, like joysticks. The
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adapter itself is super simple, the main brainwork was invested into the
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software. Very much simplified, it reads the joystick states and sends the data,
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via USB, to the computer, which thinks that it is communicating with a USB
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joystick.
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## What is special about this one?
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There are already plenty of gameport to USB adapters for basic analog joysticks
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and, as far as I know, there were some efforts to communicate with Sidewinder
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joysticks by Microsoft as well. But there is no universal adapter, which would
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work with different types of joysticks. This adapter implements multiple drivers
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for various analog and digital joysticks, with an option to add more, in the
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future.
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Features overview:
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* Support for generic analog joysticks with 2/4 buttons and 2/4 axes
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* Four switches to select joystick type
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* Autodetection for various digital protocol joysticks
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* Auto-Calibration
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* Very low input lag
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## What is the difference between analog and digital joystick?
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Many people call button-only joysticks or gamepads digital. This is kind of
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right, because a button is either pressed or not. You can't have an analog
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values in between. However by digital, in this case, we mean something different.
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A gameport contains 15 pins, 8 of which are used for joystick communication. 4
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pins are for buttons and carry digital values in sense of on/off and 4 pins are
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for analog axes, which deliver voltage somewhere between 0V and 5V. Joysticks
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which were made in the early days used this pinout. They could have a
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maximum of 4 buttons and 4 axes and were DOS compatible. Later, in the time of
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Windows 95/98 many joysticks were made to be plugged into a gameport as well,
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but they were not limited to 4 buttons and 4 axes. They had a lot more exciting
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features, like hat switches and throttle controls. But how did this work? Well
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the manufacturers implemented their drivers to communicate with the joystick via
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gameport using a proprietary communication protocol. For example, by using one
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pin of the gameport as clock and another one as data, the possibilities were
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almost limitless. Such joysticks are called digital as well, because they used
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digital protocols to communicate with the PC. And suddenly, many features were
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possible, but the price of these features was the lost compatibility to DOS. You
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couldn't just plug such a joystick into the gameport and expect it to work in
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old DOS games. The plug was the same, but the signaling was completely different.
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## Which joysticks does this adapter support?
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Currently, the following drivers are implemented. To select the right driver, you
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have to use four switches, as shown in the table. The switches may be changed or
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extended in the future, so please pay attention to the updates.
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Joystick Model | Buttons | Axes | Hat | SW1-4 | Protocol | Comments
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-----------------------------|---------|-------|------|-------|------------|------------------------------------
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Generic Analog | 2 | 2 | 0 | 0000 | Analogue |
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Generic Analog | 4 | 2 | 0 | 1000 | Analogue |
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Generic Analog | 4 | 3 | 0 | 0100 | Analogue | 3rd Axis is throttle
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Generic Analog | 4 | 4 | 0 | 1100 | Analogue |
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CH FlightStick | 4 | 4 | 1 | 0010 | Analogue |
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CH F16 Combat Stick | 10 | 3 | 1 | 0110 | Analogue |
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ThrustMaster | 4 | 3 | 1 | 1010 | Analogue | FCS MARK I/II & PFCS
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Sidewinder GamePad | 10 | 2 | 0 | 1110 | Sidewinder |
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Sidewinder 3D Pro | 8 | 4 | 1 | 1110 | Sidewinder |
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Sidewinder 3D Pro Plus | 9 | 4 | 1 | 1110 | Sidewinder | First version of Precision Pro
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Sidewinder Precision Pro | 9 | 4 | 1 | 1110 | Sidewinder |
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Sidewinder FFB Pro | 9 | 4 | 1 | 1110 | Sidewinder | FFB not yet implemented
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Sidewinder FFB Wheel | 8 | 3 | 0 | 1110 | Sidewinder | FFB not yet implemented
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Gravis GamePad Pro | 10 | 2 | 0 | 0001 | GrIP |
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Logitech WingMan Extreme | 6 | 3 | 1 | 1001 | ADI |
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Logitech CyberMan 2 | 8 | 6 | 0 | 1001 | ADI |
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Logitech WingMan Interceptor | 9 | 3 | 3 | 1001 | ADI | 2 hats are mapped as 4 axes
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Logitech ThunderPad Digital | 8 | 2 | 0 | 1001 | ADI | Directional buttons mapped as 2 axes
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Logitech WingMan Gamepad | 11 | 2 | 0 | 1001 | ADI | Directional buttons mapped as 2 axes
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Logitech WingMan Light | 2 | 2 | 0 | 0000 | Analogue |
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*Remarks:*
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- Please pay attention to how the same switches are used for different families
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of digital devices. This is possible due to fully digital communication. Using
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this method, the adapter implements autodetection as soon as it knows, that it
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is connected to a digital joystick.
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- Currently, only the drivers for the listed Sidewinder devices are implemented,
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since I have no other models at hand. The Precision Pro works natively on USB
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as well, but was still implemented, because we can.
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- Gravis used their GrIP protocol, which is currently implemented only for the
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Gravis GamePad Pro, but without daisy chaining possibility so far.
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- The implementation of the ADI protocol used by Logitech should work with all
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the devices which support that protocol. However only the listed Logitech devices
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were tested so far.
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## Which joysticks were tested?
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Many joysticks in the wild are using the same digital protocol or are backwards
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compatible to the analog joysticks as they were used back in the days in DOS.
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Following list contains all the devices which were reported by others as working
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so far:
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* CH Mach I+ (analog, 2-axes, 2-buttons)
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* Gravis Analog Pro (analog)
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* Gravis GamePad Pro
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* Gravis PC GamePad (analog)
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* InterAct UltraRacer PC (analog)
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* Logitech CyberMan 2
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* Logitech WingMan Extreme Digital
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* Logitech WingMan Interceptor
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* Logitech WingMan Light
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* Logitech ThunderPad Digital
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* Logitech WingMan Gamepad
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* Medion Joypad MD9823 (analog, 4-axes, 4-buttons)
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* QuickShot QS-123E "Warrior 5" (analog)
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* Quickshot QS-146 "Intruder 5" (analog)
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* Quickshot QS-151 "Aviator" (analog)
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* QuickShot QS-201 "Super Warrior" (analog)
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* QuickShot QS-203 "Avenger" (analog)
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* Sidewinder 3D Pro
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* Sidewinder 3D Pro Plus
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* Sidewinder ForceFeedBack Pro
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* Sidewinder ForceFeedBack Wheel
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* Sidewinder GamePad
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* Sidewinder Precision Pro
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Sidewinder 3D Pro can be switched between analog and digital mode and in analog
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mode it can emulate the ThrustMaster and CH FlightStick. That's why you see them in
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the table above. Unfortunately I don't possess those joysticks in reality, so it may
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be that the implementation is not quite correct.
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## What is auto calibration?
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Old analog joysticks have resistors inside, which are specified to be 100 kOhm.
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Unfortunately, these resistors are either worn out, bad quality or were wrong from
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the beginning. Therefore most of the generic analog joysticks had adjustment
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screws to correct the center point of the joystick. Also many games had
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calibration options in their settings to readjust the joystick. With USB and new
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digital solutions the calibration was not required anymore and was completely
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implemented in the joysticks and/or drivers. Many modern games have no option
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to re-calibrate the joystick anymore. If we try to play such newer games with
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an old analog joystick through this adapter, the joystick center point would be
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totally offset. That's why the adapter implements auto calibration internally and
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presents already corrected values to the operation system.
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__ATTENTION__: a hard requirement for using the analog joysticks is that during
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plugging into the USB port all axes must be in their middle state, because all
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the subsequent calibration happens based on the initial state.
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## Technical insights into implementation
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The code is well documented, so if you are interested in the details, feel free
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to take a look into the driver implementation. All the analog joysticks were
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actually a straight forward task, but the Sidewinder digital protocol was kind
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of tough. There are already some implementations of Sidewinder protocol made for
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Arduino. However, they are mostly only for the Sidewinder GamePad and not really
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universally made. In the end I was heavily inspired by the Linux Sidewinder
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driver implementation. The code you can see in this project is a complete rewrite,
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I just took the Linux driver implementation as a reference to understand how it
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works. Also the Sidewinder patent US#5628686A helped a lot, especially with
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switching between digital and analog mode for Sidewinder 3D Pro.
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In opposition to the already mentioned Sidewinder for Arduino implementations,
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this one doesn't rely on interrupts. This implementation is from a similar idea
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to what the Linux driver does. It polls the port and makes a lot of things
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simpler due to synchronous process. The biggest problem was that the Sidwinder
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devices send the data incredibly fast, with a clock pulse of only 5us. It was
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not possible to use Arduino's digitalRead(...) function for that. It was too
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slow with about 2.7us per call on an Arduino Pro Micro of 16MHz. It simply
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made it impossible to poll 5us pulses, with such a slow function, not even
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considering doing something with the data in between. So out of that need, my
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own implementation came about, which is up to 50% faster and needs only about
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1.6us per call, on the same hardware. The custom I/O functions made it possible
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to read the data with the speed which a Sidewinder joystick requires. The best
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part is that the code is written in pure C++. It is very simple to read and to
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use. There are no macros, no assembler or any dirty hacks, just a lot of
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optimization.
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## Bill of materials (BOM)
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The hardware is super simple. To build an adapter you'll need the PCB from this
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project and following parts:
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Part | Qty | [LCSC](https://lcsc.com/) # | [Digikey](https://www.digikey.com/) # | [Mouser Electronics](https://www.mouser.com/) # | Comment
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--------|-------|---------|--------------------------|----------------------|------------------------------------------
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CONN1 | 1 | C77835 | 609-5371-ND | 523-L77SDA15SA4CH4F | DB15 female connector
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R1..R4 | 4 | C172965 | 13-MFR-25FTE52-100KCT-ND | 603-MFR-25FTE52-100K | 100 kOhm resistors
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SW1 | 1 | C15781 | 2449-KG04ET-ND | 642-DS04T | DIP-4 switch
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U1 | 1 | C72120 | ED3051-5-ND | 649-DILB24P-223TLF | DIP24 Socket (optional)
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U1 | 1 | N/A | 1568-1060-ND | 474-DEV-12640 | Arduino Pro Micro (ATmega32U4 16MHz, 5V), including two 12 pin header connectors, MicroUSB version (see "Known issues")
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## Known issues
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* *Some axes on an analog joystick are offset*
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Auto calibration requires all the axes to be in the center position during
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initialization. Please see the paragraph about auto calibration.
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* *Joystick doesn't work*
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Make sure that you are using one of supported joysticks or a joystick which can
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work in legacy analog mode
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* *MicroUSB port on the Arduino is not stable enough*
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Use the USB-C version of the Arduino instead.
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Or always keep the MicroUSB cable attached to the Arduino MicroUSB version to avoid further wear and apply plug/unplug operations only on the remote side of the cable.
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## How to help the project?
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The best way is to implement more drivers. Since I have only the joysticks
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mentioned above, I can't contribute more than what is currently included.
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## Special thanks
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I would like to give some special thanks to *Creopard* from the German
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dosreloaded.de community for providing me the mentioned joysticks. Without that
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donation this project wouldn't be possible. Especially dealing with Sidewinder
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3D Pro was a very exciting task.
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## Links
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* [Linux Sidewinder Driver](https://github.com/torvalds/linux/blob/master/drivers/input/joystick/sidewinder.c)
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* [Sidewinder patent](https://patents.google.com/patent/US5628686A/en)
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* [Creopard Retro Site](https://www.creopard.de/)
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