Read controller input

Build and try it

Follow the tool setup, then run this from the SDK checkout:

make disc EXAMPLE=hello-input

Open build/examples/mipsel-sony-psx/release/hello-input.cue in the desktop emulator. Keep its BIN beside it. In the browser example, click the screen to give it keyboard focus. Arrow keys change the background; F / G / H / X are Cross / Circle / Square / Triangle and draw a coloured triangle. Right resets the background.

Poll once each frame

PadReader::poll_on(&mut port) returns the controller's connection mode, buttons and stick values. port is the controller-port token from Peripherals, shared with the memory card driver. A PadReader is bound to one socket (PadReader::port1() or port2()), and when a poll comes back garbled it returns the last clean state instead, so a held button does not read as released for one frame and then as a fresh press. Read it once at the beginning of your update and share that snapshot with the rest of your game:

let mut port = peripherals.controller_port;
let mut reader = PadReader::port1();

// Inside the loop:
let state = reader.poll_on(&mut port);
let pad = state.buttons;
if pad.is_held(button::UP) {
    r = r.saturating_add(4);
}

This is the pattern in hello-input. saturating_add stops at 255 instead of wrapping a bright channel back to black. The screen prints the held button names, so you can compare the input you expect with the packet the program read.

Trigger an action once

Movement usually continues while a button is held. Jumping, selecting a menu item or starting a sound usually happens once when the button goes down. Keep the previous frame's state to distinguish them:

// Before the loop:
let mut previous = ButtonState::NONE;

// Inside the loop, after polling:
let cross_pressed = pad.is_held(button::CROSS)
    && !previous.is_held(button::CROSS);
if cross_pressed {
    r = 255;
}
previous = pad;

This is a small change you can make in hello-input; import ButtonState if it is not already imported. Rebuild and hold Cross: the action happens on the first frame. Release and press again to trigger it again. The audio guide uses this same technique.

Check the connection and analogue mode

A physical controller can disconnect or change mode. Use state.is_connected() before relying on input, and state.is_analog() before using state.sticks. The example displays the mode and raw stick bytes. It also asks for analog mode at boot with require_analog_on and asks again if a pad is plugged in later, because a program started from a launcher inherits whatever mode the last program left. Digital directional buttons and analogue axes are different inputs; do not assume a pad always returns stick data.

Try a change

Change the colour step from 4 to 1, rebuild, and compare how long it takes to reach full brightness. Then change the Cross action to reset all three channels. Changes to the local source affect your rebuilt program; the player above remains the published example.

If nothing responds

Click the game screen, release any held keys and try again. The page shortcuts do not control an unfocused player. On a phone, use a connected keyboard or controller; this player has no touch D-pad. Test physical controllers on the desktop emulator and original hardware as well: browser input is not a controller-transport test.