Tutorial – iCode

July 10, 2026 BY Ali Jani

IN Blog

How to Set Up Atari Joysticks & Paddles in RetroArch with the Duo Ultimate H1 USB Adapter (Windows)

Setup Guide

A friendly, step-by-step walkthrough for Windows. By the end, your classic Atari joysticks and paddles will play smoothly in RetroArch — including up to four paddle players.

The Duo Ultimate H1 is a USB adapter that lets you plug real Atari joysticks and paddles into your PC. RetroArch can then use them to play Atari 2600 games. This guide covers the whole process from plugging in to saving your settings, and it’s written for beginners — no prior RetroArch experience needed.

What you’ll need

A Windows PC with RetroArch installed (this guide uses version 1.21.0)
The Duo Ultimate H1 USB adapter
Your Atari joystick(s) and/or paddle(s)
The Stella 2014 core installed in RetroArch (see the note below)
Your Atari 2600 game files

Important: use the right core for paddles

For paddles, use the Stella 2014 core — not the regular Stella core. Stella 2014 supports full 4-player paddles. The regular Stella core currently has a bug that limits it to 1-player paddles.

Adapter settings

Leave the Duo Ultimate on its default mode: Stick + Paddles, Left Analog. Since we’re playing Atari games with Atari paddles, keep any mouse option on standby or off.

1. Connect the adapter (order matters)

The Duo Ultimate is detected most reliably if you start it in this order:

Start RetroArch first, while the Duo Ultimate is still powered off.
Now power on the Duo Ultimate. RetroArch should detect it automatically. You’ll usually see a couple of small notifications float up from the bottom of the screen — typically “PS3 Controller 1” and “PS3 Controller 2.” Those are the adapter’s two ports (two players), and it’s a good sign.

Don’t worry if you don’t see the pop-ups — we’ll verify everything by hand in the next steps.

Why “PS3 Controller”? Windows recognizes the Duo Ultimate as a PS3-style gamepad — that’s just its default emulation mode. It behaves like an ordinary game controller plugged into your PC.

2. Set up Player 1 (Port 1) in RetroArch

First we’ll tell RetroArch which physical controller is Player 1 and teach it which buttons do what.

Open the input binds

From the RetroArch main menu, go to the top-level Settings menu → Input → RetroPad Binds.

RetroArch Input menu with RetroPad Binds highlighted — Settings → Input → RetroPad Binds.

Inside RetroPad Binds you’ll see Port 1 Controls, Port 2 Controls, and so on. Each port is a player: Port 1 = Player 1, Port 2 = Player 2.

Point Port 1 at the adapter, and keep it analog

Open Port 1 Controls and check two settings near the top:

Device Index should read PS3 Controller (1). It’s usually set automatically. If it isn’t, press Enter on Device Index and pick PS3 Controller (1) from the list.
Analog to Digital Type should be None. This keeps your input as true analog — essential for paddles, which need smooth, continuous left-and-right motion rather than being chopped into digital left/right.

Port 1 Controls showing Device Index set to PS3 Controller (1) — Port 1 → Device Index set to `PS3 Controller (1)`.

Map the buttons

Scroll down past Device Index to the list of buttons (D-Pad Up, B Button, and so on). Leave the D-Pad on its defaults. To set a button, select it and press Enter — RetroArch gives you about 2 seconds to press the button you want before it times out, so press and hold the button on the Duo until it registers.

Map these six:

RetroArch button	Press & hold on the Duo	Should show
B Button	Red	`Button 0`
A Button	Green	`Button 1`
Y Button	Blue	`Button 2`
X Button	Yellow	`Button 3`
Select	White	`Button 9`
Start	Black	`Button 8`

Heads up: A and B can look swapped

On some units the red and green buttons appear reversed. The reliable rule is to match by button number: B Button = Button 0 and A Button = Button 1. If your colors don’t match the table, trust the button number shown on screen.

Map the joystick directions

Keep scrolling to the Left Analog entries and move your joystick in each direction to bind it. These come out as axes:

RetroArch bind	Move joystick	Should show
Left Analog Y- (Up)	Up	`Axis -1`
Left Analog Y+ (Down)	Down	`Axis +1`
Left Analog X- (Left)	Left	`Axis -0`
Left Analog X+ (Right)	Right	`Axis +0`

Port 1 Controls showing button numbers and Left Analog axis assignments — Port 1 buttons (top box) and the Left Analog axes for joystick directions (bottom box).

3. Set up Player 2 (Port 2)

Set up Port 2 Controls the same way you did Port 1, with one difference:

Device Index must be PS3 Controller (2) — the number (2), not (1).
Analog to Digital Type = None, same as before.
Map the buttons and joystick directions just like Port 1 — except you can skip Select and Start. On the Duo Ultimate, the Start and Select buttons live on Port 1 only, so they don’t matter for Port 2.

Make sure Port 1 and Port 2 use different device indexes. If both are set to PS3 Controller (1), the two players share one physical port and it won’t work.

4. Turn on paddles in Stella 2014

The steps above cover joysticks. Paddles need one more layer of setup inside a game, using the Stella 2014 core.

Load an Atari 2600 game (for example, Breakout) using the Stella 2014 core, then press F1 to open the RetroArch Quick Menu.
Choose Controls.

RetroArch Quick Menu with Controls highlighted, Stella 2014 core — In-game: press F1 → **Controls**. (Note “Stella 2014” at the bottom.)

Port 1 → Players 1 & 2

Open Port 1 Controls and set Device Type to Paddles (Stelladaptor). RetroArch relabels the controls to paddle functions. Confirm:

B Button → P1 Fire
A Button → P2 Fire

Port 1 Controls with Device Type Paddles (Stelladaptor), B Button as P1 Fire and A Button as P2 Fire — Port 1 → Device Type `Paddles (Stelladaptor)`; B = P1 Fire, A = P2 Fire.

The paddle dials (the twist knobs) come from the Left Analog stick automatically: the X axis is Player 1’s paddle and the Y axis is Player 2’s paddle. So Port 1 alone gives you two paddle players.

Port 1 Left Analog axes mapped to P1 Wheel and P2 Wheel — Left Analog X = P1 paddle wheel, Y = P2 paddle wheel.

Port 2 → Players 3 & 4

For four-player paddle games, open Port 2 Controls, set Device Type to Paddles (Stelladaptor), and confirm:

B Button → P3 Fire
A Button → P4 Fire

Port 2 Controls with Paddles device type, B Button as P3 Fire and A Button as P4 Fire — Port 2 → Device Type `Paddles (Stelladaptor)`; B = P3 Fire, A = P4 Fire.

As with Port 1, the paddle dials come from the analog axes: X = Player 3, Y = Player 4.

Port 2 Left Analog axes mapped to P3 Wheel and P4 Wheel — Left Analog X = P3 paddle wheel, Y = P4 paddle wheel.

5. Save your settings so you only do this once

To avoid redoing the paddle setup for every game, save it as a core remap. Still in the Controls menu, choose Manage Remap Files.

Controls menu with Manage Remap Files highlighted — Controls → **Manage Remap Files**.

Then choose Save Core Remap File. This applies your paddle setup to every game you load with the Stella 2014 core. (If you’d rather limit it to one game or one folder, the Save Game Remap and Save Content Directory Remap options are right there too.)

Manage Remap Files with Save Core Remap File highlighted — Choose **Save Core Remap File** to apply this to all Stella 2014 games.

6. Troubleshooting & tips

Nothing detected when you power on the Duo? Make sure you started RetroArch first, then powered the adapter. Try toggling it off and on.
Both players move together / Player 2 does nothing? Check that Port 1 = PS3 Controller (1) and Port 2 = PS3 Controller (2) — not both on (1).
A and B feel reversed? The colors can differ between units. Map by button number: B = Button 0, A = Button 1.
Paddles jump around or only one player works? Confirm you’re on the Stella 2014 core (not regular Stella), that Device Type = Paddles (Stelladaptor), and that Analog to Digital Type = None.
Using paddles? Keep any mouse device on standby/off so it doesn’t interfere.

7. Quick reference tables

Port 1 button binds (Settings → Input → RetroPad Binds)

RetroArch button	Value	Color (may vary)
B Button	`Button 0`	Red
A Button	`Button 1`	Green
Y Button	`Button 2`	Blue
X Button	`Button 3`	Yellow
Select	`Button 9`	White
Start	`Button 8`	Black
Left Analog Y- / Y+ (Up/Down)	`Axis -1` / `Axis +1`	Joystick
Left Analog X- / X+ (Left/Right)	`Axis -0` / `Axis +0`	Joystick

Paddle mapping (Stella 2014, Device Type = Paddles)

Frontend port	Fire buttons	Paddle dials (Left Analog)	Players
Port 1	B = P1 Fire, A = P2 Fire	X = P1, Y = P2	Players 1 & 2
Port 2	B = P3 Fire, A = P4 Fire	X = P3, Y = P4	Players 3 & 4

That’s it — your Atari joysticks and paddles should now play beautifully in RetroArch. Load up Breakout or Warlords and enjoy the classics the way they were meant to be played.

June 30, 2026 BY Ali Jani

IN Blog

How to Set Up 4-Player Paddles on MiSTer FPGA with the iCode Duo Ultimate

⏱️ Time
10 minutes

🎯 Difficulty
Beginner-friendly

🕹️ Hardware
iCode Duo Ultimate

🎮 Game
Warlords (Atari 7800 core)

Want to play Warlords four-player on a MiSTer FPGA? The iCode Duo Ultimate reads both paddles on each of its two DB9 ports and presents them to MiSTer as two USB gamepads — giving you all four paddles. This quick-start walks you through the exact device and core settings, including the one button-mapping trick that trips most people up.

What You’ll Need

iCode Duo Ultimate adapter
Two pairs of Atari paddles (CX-30) — one pair in Port 1, one pair in Port 2
A MiSTer FPGA with the Atari 7800 core installed
A USB keyboard connected to the MiSTer (for the menus)

Step 1 — Configure the Duo Ultimate

On the adapter, set the following (save to a preset so it’s one-tap next time):

Emulation Mode → Classic. This is the most reliable mode for MiSTer — it presents a controller identity MiSTer maps correctly out of the box.
Console → Atari, and set each port’s device to Paddles (or Stick+Paddles for auto-detect).
Dual Paddles → Combined. Each port becomes one USB gamepad carrying its two paddles.
Function → Left Analog. This routes the paddles onto the left-stick X and Y axes — the axes MiSTer’s paddle support reads. (On the right stick or triggers, MiSTer ignores them.)

Plug the Duo into the MiSTer’s USB port. You now have two gamepads: Gamepad 1 = Port 1’s paddles (X = Paddle A, Y = Paddle B), Gamepad 2 = Port 2’s paddles (X = Paddle A, Y = Paddle B).

Reading the display: The Duo shows a yellow dot (Paddle A / 1A) and a blue dot (Paddle B / 1B) that track each paddle’s live position. Keep both paddles centered at the 12 o’clock position whenever you’re not actively turning one — if a paddle drifts off-center, both the button mapping and the player assignment become much harder. Re-center to 12 o’clock between every step.

Step 2 — Configure the Atari 7800 Core

Load the Atari 7800 core, open the OSD (F12), and go to the Peripherals menu:

Port1 Input → Paddle
Port2 Input → Paddle
Allow Multi Paddles → Yes (this lets each gamepad supply two paddles — one on X, one on Y)

Then run a Hard Reset (or reload the game). This is required — it clears any previous paddle assignments so the next steps start clean.

Step 3 — Map the Buttons (the important part)

Directions and paddle buttons are defined inside the core’s own setup — and the directions are mapped by turning the paddles, not by pressing anything, because in Combined mode each paddle is a stick axis. Keep both paddles at 12 o’clock except when a prompt asks you to move one, and always return to 12 o’clock before the next prompt.

In the Atari 7800 core OSD, open “Define Atari 7800 buttons.”
RIGHT: turn Paddle 1A (yellow dot) clockwise, then back to 12 o’clock.
LEFT: turn Paddle 1A (yellow dot) counter-clockwise, then back to 12.
UP: turn Paddle 1B (blue dot) counter-clockwise, then back to 12.
DOWN: turn Paddle 1B (blue dot) clockwise, then back to 12.
FIRE 1 — skip it (press Space on the keyboard, or the User button).
FIRE 2: press the Paddle 1B fire button.
Select and Start / Reset: press the black and white buttons on the Duo.
Skip any other prompts you don’t need.
At the very end it asks for PADDLE BUTTON — press the Paddle 1A fire button.

Critical: Do not map FIRE 1. If FIRE 1 is mapped, the core will not let you assign the Paddle Button, and your paddle triggers won’t work. Skipping FIRE 1 is what frees up the Paddle Button slot.

Step 4 — Assign the Four Paddles

With both ports set to Paddle, Multi Paddles on, and the core freshly reset, load Warlords and assign each paddle by turning it fully to its stop, then back to 12 o’clock. Watch for the on-screen “Assigned” confirmation after each one, and do them in this order:

Turn Port 1, Paddle A fully → Paddle 1A Assigned (Player 1)
Turn Port 1, Paddle B fully → Paddle 1B Assigned (Player 2)
Turn Port 2, Paddle A fully → Paddle 2A Assigned (Player 3)
Turn Port 2, Paddle B fully → Paddle 2B Assigned (Player 4)

Order matters — the paddles fill the four slots in sequence, so assign them one at a time and wait for each confirmation. Keeping the other paddles centered at 12 o’clock while you do this prevents the wrong paddle from grabbing a slot. That’s it: four players, four paddles.

Quick Reference

Emulation Mode: Classic
Dual Paddles: Combined | Function: Left Analog
Core (Peripherals): Port1 = Paddle, Port2 = Paddle, Allow Multi Paddles = Yes
Display dots: yellow = Paddle 1A, blue = Paddle 1B — keep paddles at 12 o’clock unless actively turning one
Buttons (Define Atari 7800 buttons): directions = turn the paddles (Right/Left = 1A yellow CW/CCW, Up/Down = 1B blue CCW/CW, each back to 12); skip Fire 1; Fire 2 = Paddle 1B button; Select/Start = Duo black & white buttons; Paddle Button = Paddle 1A button
Assign order: Port 1 A → Port 1 B → Port 2 A → Port 2 B (turn each fully, wait for confirmation)
Always Hard Reset the core after changing paddle settings.

- Atari Dual Paddles as Independent Gamepads? Here’s How the iCode Ultimate Adapter Has the Answer

How to Set Up Atari Joysticks & Paddles in RetroArch with the Duo Ultimate H1 USB Adapter (Windows)

1. Connect the adapter (order matters)