---
title: "Input"
canonical_url: https://developer.repebble.com/pebbleos/docs/architecture/input/
last_updated: 2026-10-12
sdk_version: 4.33.1
---
# Input

Source: https://developer.repebble.com/pebbleos/docs/architecture/input/

`subsys/input/` carries input events from the drivers to the code that consumes them. Its public API is `include/pbl/input/input.h`. It is modelled on the Zephyr input subsystem: drivers report events without knowing who consumes them, and listeners are defined next to the code they drive and collected at link time.

## Events

An event is a type, a code and a value:

- `PBL_INPUT_EV_KEY`: a key or button, with value 1 when pressed and 0 when released. The codes `PBL_INPUT_KEY_BACK`, `_UP`, `_SELECT` and `_DOWN` are the watch buttons, set per button in the board configuration; `PBL_INPUT_BTN_TOUCH` is the touch contact.

- `PBL_INPUT_EV_ABS`: an absolute axis, `PBL_INPUT_ABS_X` and `_Y` in pixels for touch.

- `PBL_INPUT_EV_GES`: a gesture recognized by the device (tap, double tap, palm), located at the report’s `ABS_X` and `ABS_Y`.

Events are grouped in reports, the last one carrying `sync`. A touch sample is `BTN_TOUCH`, `ABS_X`, `ABS_Y` (sync); a gesture is `ABS_X`, `ABS_Y`, `GES` (sync); a button is a single `KEY` event with `sync`.

## Delivery

`pbl_input_report()` calls every listener before it returns, in the context of the report: the debounce ISR for buttons, the system task for touch, the calling thread for injected input. There is no queue or thread of its own; the listeners that need to defer work already have the kernel event queue.

Listeners are registered with `PBL_INPUT_CALLBACK_DEFINE()` and must not block. Those that use APIs that are not ISR-safe check `pbl_in_isr()`.

```
static void prv\_input\_cb(const struct pbl\_input\_event \*evt, void \*user\_data) {if (evt-\>type == PBL\_INPUT\_EV\_KEY && evt-\>code == PBL\_INPUT\_KEY\_BACK && evt-\>value) {...}}PBL\_INPUT\_CALLBACK\_DEFINE(prv\_input\_cb, NULL);
```

The firmware has two listeners:

- `fw/kernel/input_buttons.c` turns key events into `PEBBLE_BUTTON_DOWN_EVENT` / `PEBBLE_BUTTON_UP_EVENT`, so the click recognizers and everything above them are unchanged.

- The touch service (`fw/services/touch/touch.c`) collects each report and passes it to `touch_handle_update()` and `touch_handle_gesture()`.

The SELECT+BACK hard reset stays in the button drivers: it has to work when every thread is wedged, so it runs in the debounce timer ISR that also times how long the buttons are held.

## Injection

Injected input goes through the same path as the hardware:

- `input report <key|abs|ges> <code> <value> [sync]` reports any event, and `input dump on` logs every event (`CONFIG_INPUT_SHELL`).

- `button raw <btn> <0|1>` reports a button transition.

- `button click` / `hold` / `multi` and the remote input endpoint (`fw/kernel/remote_input.c`) report their button presses.

Injected touch gestures (`touch_handle_injected_update()`) still go straight to the touch service, which arbitrates between them and the physical sensor.

Generated from PebbleOS [07809a65c](https://github.com/coredevices/pebbleos/commit/07809a65c0cdc306f574a2c4b0ebf74b8f930010). This page is maintained in the pebbleos repository: [docs/architecture/input.md](https://github.com/coredevices/pebbleos/blob/07809a65c0cdc306f574a2c4b0ebf74b8f930010/docs/architecture/input.md).