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HayBox uses specific button combinations held while plugging in the controller to access special modes and select communication backends. This page documents all available button hold combinations.

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Button Hold Diagram

Button hold diagram

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Special Modes

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Config Mode (Pico Only)

This mode is only available on Pico/RP2040-based devices.
To enter config mode, hold MB1 (Start) on plugin. Config mode allows you to modify controller settings without reflashing the firmware.

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Pico Bootsel Mode

This is a quick way to reflash firmware on Pico-based controllers without physically pressing the bootsel button.
To reboot Pico-based controllers into bootsel mode, hold RT2 (C-Down) on plugin. This is checked very early during boot for safety reasons. Once in bootsel mode, you can drag and drop a new .uf2 firmware file to update your controller.

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Brook Board Passthrough Mode

Available on GCCPCB2, GCCMX, B0XX R2, and LBX configurations.
To switch to Brook board mode, hold RF1 (B) on plugin. This mode allows you to use an integrated Brook board for communication instead of the HayBox firmware.

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Communication Backend Selection

On Pico/RP2040 devices, HayBox automatically detects whether you’re plugged into:
  • USB - Defaults to XInput mode
  • GameCube console - Automatically detected
  • Nintendo 64 console - Automatically detected

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Manual Backend Selection

You can override the default USB backend by holding these buttons on plugin:
ButtonBackendDescription
RF2 (X)Nintendo Switch USBAlso sets initial game mode to Ultimate
RF3 (Z)DInputOnly recommended for games that don’t support XInput
XInput is the default and recommended backend for most PC games as it provides the best compatibility.

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Polling Rate Configuration

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Arduino/AVR Polling Rate

On Arduino devices, you can configure the polling rate in your config file. The polling rate value is passed to the backend constructor: 
GamecubeBackend *gamecube_backend = new GamecubeBackend(inputs, input_sources, input_source_count, pinout.joybus_data, 125);
Common polling rates:
  • 125 - Standard GameCube console (125Hz)
  • 1000 - Overclocked adapter (1000Hz)
  • 0 - Disable lag fix completely
While 1000Hz works on console, it will result in more input lag. The polling rate setting allows the GameCube backend to read inputs right before the next poll for optimal freshness.

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Pico/RP2040 Polling Rate

Pico/RP2040 devices do not require polling rate configuration.
The Pico has enough processing power to read and process inputs after receiving the console poll, eliminating the need to predict when polls will arrive.

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Button Naming Reference

HayBox uses a consistent button naming scheme:
  • LF = Left Face (L, Left, Down, Right)
  • LT = Left Top (Mod X, Mod Y)
  • MB = Middle Buttons (Start, Select, Home)
  • RT = Right Top (A, C-Down, C-Left, C-Up, C-Right)
  • RF = Right Face (B, X, Z, Up, R, etc.)
The exact mapping depends on your controller configuration. See your config/<environment>/config.cpp file for the specific pin mappings.

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