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Atari style joystick/controller to USB adapter
Content: The idea | Project overview | Schematic | Programming the microcontroller | Source code | Printed Circuit Board for surface-mount version | Assembling the surface-mount version | Pictures and screenshots | Pictures from users | Disclaimer
The idea [hide]
For playing good old games with an emulator, nothing beats the original controllers. There was a time where many game consoles and computers used a DB9 connector for joysticks and controllers. This projects aims to adapt all these controllers on USB ports.

Many people like me have been happy doing this with simple homebuilt parallel port adapters for years but unfortunately, parallel ports are becoming less common these days (Some computers dont have any parallel ports!). Also, modern game controllers uses USB.

That's why I decided to build my own DB9 controller to USB adapter. At the moment, the following controllers are supported:
  • 1 Button Atari and compatibles
  • 2 Button controllers, such as Sega master system
  • Genesis controllers, 3 and 6 button flavors
Genesis 3 buttons

Genesis 3 buttons

Genesis 6 buttons

Genesis 6 buttons

Sega master system

Sega master system



However, due to the way USB works, the adapter is a little more complicated.

Note: The project on this page can also be used for NES and SNES controllers. Visit the SNES/NES gamepad (and mouse) to USB adapter project page.
Ready-built Atari to USB adapters available

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Project overview [hide]
I built my adapter using an ATmega8 microcontroller from Atmel. This microcontroller does not support USB in hardware so I used the software-only usb driver from Objective Development. This driver allows an AVR microcontroller such as the ATmega8 to talk USB with minimal external components. As a result, the interface can be built cheaply and easily, thanks to the low component count.

Depending on your skills, you may build the interface using breadboard and thru-hole components or the surface mount version, using the PCB artwork I provide. I also sell pre-assembled PCBs and pre-programmed Atmega8 (dip package only).

pre-assembled PCBs and pre-programmed chips available
No drivers required!
That's right, since the USB standard defines device classes. I'm using the human input device (HID) which allows me to tell to the computer that the connected USB device is a joystick and has 2 axis and 4 or 8 buttons. Another nice thing about this is that the adapter should work with all operating systems supporting HID devices. (I tested and it works at least on Win98, Win2K, WinXP and Linux)

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Schematic [hide]
Here is the modern version of the schematic (for firmware 1.5 and up):

Here is the old versions of the schematic (for firmwares up to 1.4):
revE-atari.png
sch-revE-atari.pdf

Component list:
  • U2: Atmega8 microcontroller. ATMEGA8-16PC, ATMEGA8-16PI, ATMEGA8-16PJ or ATMEGA8-16PU. Dont use an ATMEGA8L-*, the 12Mhz clock would be too high.
  • R1: 1.5k resistor. Ordinary carbon film 1/4 watt resistors will do.
  • R2, R3: 68 ohm resistors. Ordinary carbon film 1/4 watt resistors will do.
  • D2, D3: 3.6 volts zener diodes.
  • Y1: 12 Mhz crystal.
  • C2, C3: 27 pf capacitors. If the crystal datasheet recommends another value, use it instead.
  • C1: 10uf capacitor. Install it near the ATmega8.
  • JP1, JP2: Jumpers. You can also use dip switches, ordinary switchs or solder bridges.
  • J2: 6 pin header, 2.54mm spacing. Needed for programming the ATmega8.
  • P1: DB9 male connector.

For the USB connection, just strip the USB cable and solder the wires directly to the board. USB uses standard wire colors:
Color Description
  Red +5 volts
  Black Ground
  Green D+
  White D-

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Programming the microcontroller [hide]
A microcontroller is a component which must be programmed in order to do something useful. So here is the hexfile which must be uploaded to the microcontroller:
FileComments
nes_snes_db9_usb-1.6.hex
  • Changed the button IDs. Atari and SMS controllers were using button 2 and 3. Some emulators require button 1 so....
  • Added a way to force 6 Button mode for genesis controllers. Just in case your 6 button controller is not detected. Hold 'start' when connecting the USB cable to use this feature.
nes_snes_db9_usb-1.5.hex
  • Added support for Genesis 3 and 6 button controllers.
  • All DB9 controllers (Genesis 3/6, SMS, Atari style 1 or 2 button and compatible) are auto-detected.
  • The wiring is now different for DB9 controllers. Easier to wire to the multiuse PCB.
  • NES controllers are now detected in SNES mode. This works great with original Nintendo controllers. If you have trouble with clones, use NES-only mode.
  • The project is now released under the GPL v2 license
snes_nes_atari_usb-1.4.hex
  • Added support for Atari style joysticks (Atari, Commodore, etc). Two button variations (eg: Sega Master System) are also supported.
  • Added padding to the nes report descriptor. This makes it work correctly on Windows. Linux sure is tolerant...
snes_nes_usb-1.3.hex
  • Fixed a bug which resulted in random button toggling when no controller was connected to the circuit.
  • NES mode now has it's own USB product ID.
  • PD1 is left in input (and no pull-up) since PD1 and PD0 must be shorted together in PCB rev.C (cleaner workaround than throwing away a batch of 50 PCBs and easier than cutting a track and soldering a wire...)
snes_nes_usb-1.2.hex Added Snes mouse support.
snes_nes_usb-1.1.hex Reworked the report descriptor for better behaviour under Windows and MacOS X
snes_nes_usb-1.0.hex Initial release.


Many microcontrollers have what is called 'Fuse bytes'. In the case of the ATmega8, there are two bytes: The high byte, and the low byte. Those bytes are used to configure some aspects of the microcontroller. What type of clock to use? Crystal? Resonator? Internal RC clock? Allow programming via ISP? It's very important to set the fuses to the right values. Using the wrong values can render your MCU unusable.

For this project, here are the appropriate fuse values:
high byte = 0xc9, low byte = 0x9f

For details about how to program an AVR, visit my AVR programming page.

Pre-programmed chips available

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Source code [hide]
For those who wish to modify the device behaviour or add support for new type of gamepads, here is the source code. Starting with version 1.5, it is released under the GPL v2 license. Previous version were released under the Objective Development license, which is basically GPL + extensions to cover hardware. See License.txt for more information.
FileComments
nes_snes_db9_usb-1.6.tar.gz
  • Changed the button IDs. Atari and SMS controllers were using button 2 and 3. Some emulators require button 1 so....
  • Added a way to force 6 Button mode for genesis controllers. Just in case your 6 button controller is not detected. Hold 'start' when connecting the USB cable to use this feature.
nes_snes_db9_usb-1.5.tar.gz
  • Added support for Genesis 3 and 6 button controllers.
  • All DB9 controllers (Genesis 3/6, SMS, Atari style 1 or 2 button and compatible) are auto-detected.
  • The wiring is now different for DB9 controllers. Easier to wire to the multiuse PCB.
  • NES controllers are now detected in SNES mode. This works great with original Nintendo controllers. If you have trouble with clones, use NES-only mode.
  • The project is now released under the GPL v2 license
nes_snes_usb-1.4.tar.gz
  • Added support for Atari style joysticks (Atari, Commodore, etc). Two button variations (eg: Sega master system) are also supported.
  • Added padding to the nes report descriptor. This makes it work correctly on Windows. Linux sure is tolerant...
nes_snes_usb-1.3.tar.gz
  • Fixed a bug which resulted in random button toggling when no controller was connected to the circuit.
  • NES mode now has it's own USB product ID.
  • PD1 is left in input (and no pull-up) since PD1 and PD0 must be shorted together in PCB rev.C (cleaner workaround than throwing away a batch of 50 PCBs and easier than cutting a track and soldering a wire...)
nes_snes_usb-1.2.tar.gz Added SNES mouse support.
nes_snes_usb-1.1.tar.gz Reworked the report descriptor for better behaviour under Windows and MacOS X
nes_snes_usb-1.0.tar.gz Initial release. Snes and Nes support.

Please contact me at raph@raphnet.net if you do useful changes.

Objective Development driver modifications:
The NES/SNES mode selection jumper changes the HID report descriptor. I had to modify Objective Development's usb driver to support this. Here is a diff against the usb driver from HIDKeys.2006-03-14:
usbdrv-diff

USB Vendor ID/Product ID pair:
Please dont re-use my VID/PID pair for derived or other projects. Instead, get your own. I bought my VID/PID pairs from mecanique, and they are much less expensive than the 2000$ US it cost to get a vendor ID from the usb implementers forum.

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Printed Circuit Board for surface-mount version [hide]
revC pcb The surface mount version has many advantages:
  • Very small (approximately 1"1/4 x 3/4" or 32mm x 20mm).
  • Fits inside 3/4 pvc pipes. Ideal for installing inline with USB connector.
  • Can be installed directly inside an Snes or Nes gamepad.
  • Less wires to solder than on a breadboard. In some ways, it's easier to build.
  • Looks more professional.
  • You can use the board for other purposes. (After all, you have a reprogrammable MCU with USB and a few IO pins)
On the other hand, soldering surface mount components is harder if you dont have appropriate equipment or if you are a beginner.

Here is a composite view of the PCB rev.C:
rev.C composite image

For reference, here is the composite view of rev.B: snes_nes_usb_pcb_revB.png
Here are the gerber files you can use to build your PCB(s):
Revision C: snesusb_revC.zip
Revision B: snes_nes_usb_PCB-revB.zip

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Assembling the surface-mount version [hide]
Step 1: Use the composite view, the schematic and component list to find out where each component goes. Solder everything in place and inspect the board carefully for solder bridges. IMPORTANT: Do a solder bridge between PD1 and PD0 (see schematic).

snes wiring Step 2: Use the appropriate diagram on the left to solder the USB, ISP and controller/joystick wires at the right places. The ISP cable can be built with a 2x3 header and a piece of flat cable. Pin numbers on diagram matches the standard atmel 6 pin AVR ISP.

Step 3: If you will be using a NES gamepad, close JP1 with a solder bridge or a small piece of wire. For DB9 gamepads, close JP1 and JP2. Refer to the pictures on the right for examples.

Step 4: Connect the USB and ISP cables. Use you programmer to program the hexfile into the ATmega8. Next, set the fuses bytes (High byte=0xc9, low byte=0x9f).

Step 5: Test the adapter with a game. If all works well, you can remove the ISP cable if you dont plan to update the firmware. Now find a way to protect the PCB. You can fit it inside a little box, a piece of PVC pipe or a heat-shrink. Also, adding hot glue near the wires you soldered on the PCB will prevent the wires from breaking near the solder points.

Step 6: Have fun!
Pre-assembled and tested version available

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Pictures and screenshots [hide]
Here are the joysticks that I use with this adapter.
Here is my first adapter. It is built with the surface-mount PCB rev.C, a male DB9 and a couple of wires.

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Pictures from users [hide]
I like to see how others build this project. Please send me your pictures and I will put some of them here.
Someone from France sent me those pictures which are an excellent example of how one can mount the circuit inside a Sega Master System controller:

Laurent Quesnel installed the circuit inside an SMS game cartridge case:

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Disclaimer [hide]
I cannot be held responsible for any damages that could occur to you or your equipment while following the procedures present on this page. Also, I GIVE ABSOLUTELY NO WARRANTY on the correctness and usability of the informations on this page. Please note, however, that the procedures above have worked in my case without any damages or problems.

Now you cannot say that I did not warn you :)

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