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Overview

HayBox’s communication backend selection allows your controller to work with different consoles and PC setups. The backend is selected through auto-detection and button holds on plugin, and you can customize this behavior in your device’s config.cpp file.

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Backend Selection Logic

Backend selection happens in the setup() function of your config file (e.g., config/pico/config.cpp or config/arduino/config.cpp).

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Pico/RP2040 Devices

On Pico-based controllers, USB vs GameCube vs Nintendo 64 is detected automatically using the detect_console() function. 
void setup() {
    static InputState inputs;

    // Create GPIO input source and read button states
    gpio_input.UpdateInputs(inputs);

    // Check bootsel button hold (RT2/C-Down)
    if (inputs.rt2) {
        reboot_bootloader();
    }

    // Initialize backends with auto-detection
    backend_count = initialize_backends(
        backends, 
        inputs, 
        input_sources, 
        input_source_count, 
        config, 
        pinout
    );
}
Pico devices don’t require polling rate configuration because they have enough processing power to read inputs after receiving the console poll.

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Arduino/AVR Devices

On Arduino-based controllers, the backend selection is more explicit: 
void setup() {
    static InputState inputs;

    // Create GPIO input source
    static GpioButtonInput gpio_input(button_mappings, button_count);
    gpio_input.UpdateInputs(inputs);

    // Create array of input sources
    static InputSource *input_sources[] = { &gpio_input };
    size_t input_source_count = sizeof(input_sources) / sizeof(InputSource *);

    // Initialize backends with detection
    backend_count = initialize_backends(
        backends,
        inputs,
        input_sources,
        input_source_count,
        config,
        pinout
    );
}

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Polling Rate Configuration

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GameCube Polling Rates

For Arduino/AVR controllers, you can configure the polling rate to match your setup. This is especially important for overclocked adapters.
1

Understand Polling Rates

The polling rate tells the firmware when to expect the next poll from the console or adapter. Common rates:
  • 125Hz: Native GameCube console
  • 1000Hz: Overclocked GameCube adapters
  • 0: Disables the polling fix (for official adapters)
2

Locate Backend Initialization

Find where GamecubeBackend is created in your backend initialization code. The polling rate is passed as a parameter to the constructor.
3

Set Your Polling Rate

Pass the appropriate polling rate value:
// For native console (125Hz)
new GamecubeBackend(inputs, input_sources, input_source_count, 125, pinout.joybus_data);

// For overclocked adapter (1000Hz) 
new GamecubeBackend(inputs, input_sources, input_source_count, 1000, pinout.joybus_data);

// For official adapter (disable fix)
new GamecubeBackend(inputs, input_sources, input_source_count, 0, pinout.joybus_data);
Using 1000Hz polling rate on console will result in more input lag, not less. Only use 1000Hz for overclocked adapters on PC.

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N64 Polling Rates

Nintendo 64 backend works similarly: 
// N64 runs at 60Hz
new N64Backend(inputs, input_sources, input_source_count, 60, pinout.joybus_data);

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Understanding the Initialization Process

The initialize_backends() function handles:
  1. Console Detection: Checks if plugged into GameCube/N64
  2. Button Hold Detection: Reads which buttons are held on plugin
  3. Backend Selection: Chooses appropriate backend based on detection
  4. Secondary Backends: Initializes additional backends (e.g., B0XX input viewer)

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Backend Configuration Structure

Backends are configured in config_defaults.hpp: 
.communication_backend_configs = {
    CommunicationBackendConfig {
        .backend_id = COMMS_BACKEND_XINPUT,
        .default_mode_config = 1,
    },
    CommunicationBackendConfig {
        .backend_id = COMMS_BACKEND_DINPUT,
        .default_mode_config = 1,
        .activation_binding_count = 1,
        .activation_binding = { BTN_RF3 }, // Hold Z for DInput
    },
    CommunicationBackendConfig {
        .backend_id = COMMS_BACKEND_NINTENDO_SWITCH,
        .default_mode_config = 3,
        .activation_binding_count = 1,
        .activation_binding = { BTN_RF2 }, // Hold X for Switch
    },
}

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Custom Backend Selection

You can implement custom backend selection logic by providing a custom function to initialize_backends(): 
void custom_backend_selector(
    CommunicationBackendConfig &backend_config,
    const InputState &inputs,
    Config &config
) {
    // Your custom logic here
    if (inputs.rf1 && inputs.rf2) {
        backend_config.backend_id = COMMS_BACKEND_DINPUT;
    }
}

void setup() {
    // Pass custom selector to initialize_backends
    backend_count = initialize_backends(
        backends,
        inputs,
        input_sources,
        input_source_count,
        config,
        pinout,
        custom_backend_selector  // Custom selector function
    );
}

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Available Backends

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COMMS_BACKEND_XINPUT
Backend
XInput mode for PC gaming. Default for Pico on USB. Works plug-and-play with most PC games.
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COMMS_BACKEND_DINPUT
Backend
DirectInput mode for PC. Default for Arduino on USB. Supports keyboard modes.
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COMMS_BACKEND_NINTENDO_SWITCH
Backend
Nintendo Switch USB mode. Automatically sets Ultimate mode as default.
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COMMS_BACKEND_GAMECUBE
Backend
GameCube console communication. Auto-detected when plugged into GameCube.
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COMMS_BACKEND_N64
Backend
Nintendo 64 console communication. Auto-detected or selected via button hold.

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Troubleshooting

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Controller Not Working with Console

Hold A (RT1) on plugin to disable the polling fix by passing 0 as the polling rate.
Requires 5V power:
  • Mayflash adapter: Both USB cables plugged in
  • Console: Rumble line must be intact
Pico devices work natively with 3.3V.
Make sure you’re using the correct polling rate (125Hz for native console). Using 1000Hz on console causes increased input lag.

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See Also

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