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SEGA Saturn controller to USB with minimal lag

Table of Contents

I'll use an original Sega Saturn gamepad (model HSS-0101) in a Mister FPGA setup using Daemonbite code.

What you need

Arduino Pro Micro ATMega32u4 5V 16MHz
USB ASP Programmer
SEGA Saturn original gamepad
Micro USB to USB male-male
22 AWG copper cable
Solder tool and solder wire
Female connector for the Saturn gamepad

Instead of Micro USB there are Mini USB versions for the Arduino Pro Micro. Although a bit pricier, the connector is way more reliable.

How to compile

Download SaturnControllerUSB
Open the .ino file from Arduino IDE
Select the board Arduino Leonardo
Compile and export to bin and save it as .hex

I've done this process so you can just skip the compilation and use the file SaturnControllerUSB.ino.with_bootloader.leonardo.hex

How to program

Programming the Arduino Pro Micro from the Arduino IDE turned into a failure, so I programmed the microcontroller using a cheap USBAsp programmer via ICSP. Just connect the pins RST, CLK, MOSI, MISO, +5V and GND and run avrdude this way:

# avrdude -c usbasp -p m32u4 -U flash:w:SaturnControllerUSB.ino.with_bootloader.leonardo.hex

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.01s

avrdude: Device signature = 0x1e9587 (probably m32u4)
avrdude: NOTE: "flash" memory has been specified, an erase cycle will be performed
         To disable this feature, specify the -D option.
avrdude: erasing chip
avrdude: reading input file "SaturnControllerUSB.ino.with_bootloader.leonardo.hex"
avrdude: input file SaturnControllerUSB.ino.with_bootloader.leonardo.hex auto detected as Intel Hex
avrdude: writing flash (32730 bytes):

Writing | ################################################## | 100% 1.65s

avrdude: 32730 bytes of flash written
avrdude: verifying flash memory against SaturnControllerUSB.ino.with_bootloader.leonardo.hex:
avrdude: load data flash data from input file SaturnControllerUSB.ino.with_bootloader.leonardo.hex:
avrdude: input file SaturnControllerUSB.ino.with_bootloader.leonardo.hex auto detected as Intel Hex
avrdude: input file SaturnControllerUSB.ino.with_bootloader.leonardo.hex contains 32730 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 1.44s

avrdude: verifying ...
avrdude: 32730 bytes of flash verified

avrdude: safemode: Fuses OK (E:CB, H:D8, L:FF)

avrdude done.  Thank you.

Wiring & Pinout

Don't forget to solder J1 in the Arduino Pro Micro in order to bypass the built-in voltage regulator to make it work at 5V.

This is the pinout for the controllers. You will need one Arduino Pro Micro for each controller.

Hembra Saturn (P1)	Arduino Pro Micro
1	VCC
2	2
3	3
4	15
5	14
6	4
7	TXO
8	RXI
9	GND

Hembra Saturn (P2)	Arduino Pro Micro
1	VCC
2	A2
3	A3
4	15
5	14
6	6
7	A0
8	A1
9	GND

How to configure

If all this has been done correctly the Arduino can be connected to the Mister FPGA and it will detect each button press. Just follow the Joystick Remapping Documentation. Basically:

Connect a keyboard and the gamepad to the Mister
Press Esc and select Define joystick buttons
Press Space for DPAD and Tilt
Press direction buttons and face buttons on the gamepad
Press Space for the mouse options
For Menu press a combination of two buttons like L + R
Once you see Press: Menu: OK press Enter

Enable fast polling

Just press B button just after powering on the Mister and a menu with the option Scripts will appear. Then select and run fast_USB_polling_on. If the gamepad you are using is not working it means it doesn't support 1000Hz mode and you need to switch back running fast_USB_polling_off.