Design your own fight stick or leverless controller, in your browser

Every custom controller starts the same way: a layout sketched on paper, a pin map in a notes app, and a lot of hoping it all works once the case is drilled. Mokxi lets you template the whole build first. Lay out the buttons, wire them to a Raspberry Pi Pico, run firmware that does what a modern controller board does, and play it with your keyboard. When it works here, you wire the real thing to the same pins.

The controller above is the leverless template, running. Press Run, then hold A and D together and watch SOCD cleaning decide what the game would get. W is up, U I O P and J K L ; are the eight attack buttons, Q E H are Select, Start and Home, and T is turbo. The OLED shows your inputs as you press them, and every lit button reacts to a press.

There are three templates on the same board and the same firmware: a leverless (all-button) layout, a traditional stick with a Sanwa-style lever, and a mixbox-style layout with W A S D under the left hand. Open one, make it yours, and save it to your account.

The templates run one firmware, written for the Pico and commented for people who build controllers. Everything you are likely to change sits in a single block at the top: the layout, the pin map, the button names, the lights, the starting SOCD rule and the timing.

Debounce adds no lag: a press counts the moment its first edge arrives, and the pin is then ignored for 5 milliseconds so the contact bounce is thrown away. SOCD cleaning offers Neutral, Up priority, Last win and First win. D-pad, left stick and right stick modes are there too, and both switch with GP2040-CE’s own button combos, with nothing reaching the game while a combo is held. Turbo is per button. The lit buttons have themes and a press fade, and the OLED input display draws your inputs and an input history in numpad notation without ever making a press wait for the screen.

The Serial Monitor is an input viewer: one line for every change in what the controller would send, with the direction in numpad notation, the buttons held, and how many 60 Hz frames the previous state lasted.

A lever’s gate cannot point left and right at once, but four buttons can be held in any combination. SOCD cleaning decides what the controller sends then. Neutral sends neither direction. Up priority, the classic Hit Box rule, sends neither for left plus right and up for up plus down. Last win lets the newer press win, and First win the older one.

Evo’s rules ask that a controller never sends opposite directions together, and name Neutral, First input priority and Last input priority as accepted methods. The Capcom Pro Tour rule for Street Fighter 6, announced in 2023, says up plus down must give neither a jump nor a crouch and left plus right neither walk, which Neutral meets and Up priority does not. Rules change by event and by game, so check the current ruleset of the event you play. The templates start in Neutral.

Build your own fight stick is a free five-lesson course that builds the leverless template a stage at a time on the same pins: one button and a lag-free debounce, the four directions with SOCD cleaning, all eight attack buttons, lit buttons with themes, and finally the full controller with its screen, mode combos and turbo. Every step is a checkpoint the simulator checks for you.