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wtf is pps-watch?

idlehandsdev/pps-watch — explained in plain English

Analysis updated 2026-05-18

23HTMLAudience · generalComplexity · 5/5Setup · hard

TL;DR

Full hardware plans for a wearable GPS timing device that outputs an ultra-precise one-pulse-per-second signal instead of showing the time.

Mindmap

mindmap
  root((PPS watch))
    What it does
      Gets GPS time fix
      Outputs 1PPS signal
      Compares external PPS
    Tech stack
      KiCad
      Fusion 360
      u-blox GPS module
    Use cases
      Precision timing reference
      Phase comparison
      Wearable GPS build
    Audience
      Hardware hobbyists
      Electronics makers

Code map

Detail Auto

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filefunction / class

Why would anyone build with this?

REASON 1

Build a wearable precision timing reference that outputs a GPS-locked pulse-per-second signal.

REASON 2

Compare an external PPS signal against a GPS-derived one using the built-in phase comparator and LEDs.

REASON 3

Order the exact components using the included bill of materials with Digikey part numbers.

REASON 4

3D print the watch frame and band mount and assemble a working GPS timing wristwatch.

What's in the stack?

KiCadFusion 360u-blox GPS74HC12574AHC1G86

How it stacks up

idlehandsdev/pps-watchjensen-yao/mdrelerry/ai-lecture-open
Stars232323
LanguageHTMLHTMLHTML
Setup difficultyhardeasy
Complexity5/51/5
Audiencegeneralwritergeneral

Figures from each repo's GitHub metadata at analysis time.

How do you spin it up?

Difficulty · hard Time to first run · 1day+

Requires ordering PCB fabrication, soldering surface-mount components, and 3D printing case parts before it works.

Wtf does this do

This repository contains the full design for a physical wristwatch that does not display the time at all. Instead, it is a precision GPS timing device you wear on your wrist, built to output an extremely accurate one-pulse-per-second signal. It is a joke on the idea of a watch, paired with genuinely serious timing hardware underneath. The device receives GPS signals to get a position and time fix, then outputs a one-pulse-per-second signal directly from the GPS module's hardware pin. That signal stays silent until the GPS locks on, then starts pulsing once per second with high accuracy. The pulse is distributed out through a BNC connector so it can be used as a timing reference for other equipment. The watch can also accept an external PPS signal and compare it against its own GPS-derived pulse using a hardware comparator chip, lighting LEDs to show whether a signal is present and whether the two pulses are in phase. Notably, there is no microcontroller and no firmware anywhere in the design: the GPS module's own hardware pin drives the LEDs and outputs directly through simple logic buffer chips. The hardware is built around a u-blox GPS module, an external antenna connected through an SMA connector, buffer and comparator chips, indicator LEDs, a coin cell battery, a switch, and a small connector for one-time configuration. The circuit board was designed in KiCad, with the mechanical case and 3D assembly modeled in Fusion 360, and the repository includes a full bill of materials with specific part numbers for ordering components. To build one, you would order the parts, have the circuit board manufactured, 3D print a frame and watch band mount from the included files, and assemble everything with a standard 22mm watch band and a handful of small screws. This is a from scratch electronics build project, not software you install, so it requires soldering skill, PCB fabrication, and a 3D printer or printing service to complete.

Yoink these prompts

Prompt 1
Explain how this project outputs a one-pulse-per-second signal without any microcontroller or firmware.
Prompt 2
Help me understand the bill of materials so I can order parts for this PPS watch.
Prompt 3
Walk me through how the XOR phase comparator circuit compares two PPS signals.
Prompt 4
Show me what I need to 3D print and assemble to build this GPS watch.

Frequently asked questions

wtf is pps-watch?

Full hardware plans for a wearable GPS timing device that outputs an ultra-precise one-pulse-per-second signal instead of showing the time.

What language is pps-watch written in?

Mainly HTML. The stack also includes KiCad, Fusion 360, u-blox GPS.

How hard is pps-watch to set up?

Setup difficulty is rated hard, with roughly 1day+ to a first successful run.

Who is pps-watch for?

Mainly general.

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