How to Build a Pebble Watchface in 2026

2026

tl;dr: I’ve been a pebble fan for a long time. With the new hardware refresh, I wanted to start building some watchfaces.

nilcoast is live on the Pebble Appstore.

The nilcoast watchface in light mode: date and battery along the top, time in large digits, steps and sleep and alarm on the left, heart rate and temperature and condition on the right. The same nilcoast watchface in dark mode— ink and paper swapped, the red accent kept.
A lovely brutalist watchface, light and dark

Features

  • iMessage counts via BlueBubbles
  • Sensor data (sleep, battery, steps, etc…)
  • Weather data from wthr.cloud
  • Seconds animation on shake/tap

Getting Started

  • toolchain lives in pebble-tool, installed with uv: uv tool install pebble-tool
  • pebble sdk install latest pulls the compiler/emu
  • pebble login— logs in to cloudpebble
  • pebble new-project <name> scaffolds the layout below

I wrote some C

Watch-side code is plain C99 against the Pebble SDK. Every watchapp’s entry point looks roughly like this — create a window, wire up handlers, open the AppMessage channel:

static void init(void) {
  draw_init();
  model_init(&s_model);
  draw_palette(s_model.invert);

  s_window = window_create();
  window_set_background_color(s_window, draw_bg());

  WindowHandlers handlers = {
      .load = window_load,
      .unload = window_unload,
  };
  window_set_window_handlers(s_window, handlers);
  window_stack_push(s_window, true);

  app_message_register_inbox_received(inbox_received);
  app_message_open(164, 64);
  ...
}

Full source: gist.

Pixel hell

Pixel perfect counts on such a small screen (numeral ink spans 8px, my icon started a row short at 7px)— I built a quick box model in C for alignment. This gives me a re-usable layout engine for future watchfaces. Feel free to use it.

Full source: gist.

static int child_main(const Box *c, int leftover, int grow_total) {
  if (c->fixed > 0) return c->fixed;
  return grow_total > 0 ? leftover * c->grow / grow_total : 0;
}

Note: Prose is mine— code was written with an LLM and a human in the loop.

Comments

← Back to Blog