A native macOS companion app for the Precision Clock Mk IV by mitxela. Lives in the menu bar — connects over USB serial to drive the clock's display, track satellites, serve GPS-disciplined NTP time, and scroll WeatherKit conditions.
Note
This is an independent, community-built companion app. Not affiliated with mitxela.
Tip
Also available as PCC Web — browser build for Chromium. WIP / POC, things may not work. See below.
|
|
Data Sources |
Satellites — Polar |
Satellites — Map |
Brightness |
Weather |
Time Server |
All screenshots
Connect |
Data Sources |
Text |
Data Sources — REST |
Data Sources — Bash |
Countdown |
|
Satellites — Polar |
Satellites — Map |
Satellites — Globe |
Modes |
Diagnostics |
Serial Monitor |
Advanced |
Updates |
- Connects over serial, auto-detects ports, reconnects after reboot
- Configure display modes, colon animation, brightness curve, diagnostics, timezone, and more
- Send text or countdowns to the display
- Poll REST APIs or shell commands and rotate values on the clock (with HTTP header support)
- Edit the 5-point brightness curve with a draggable graph; save custom presets
- Read and write
config.txtwith local backups kept on the Mac - Check for firmware and timezone updates; install to the CLOCK USB volume (auto-ejects after copy so the mass-storage write cache is flushed before reconnect)
- Three satellite views — Polar plot, world Map, and interactive 3D Globe — with consistent toggles for satellites, labels, and trails
- Per-pass trail recording: each satellite's continuous arc is captured as a distinct pass, rendered through five age tiers (live → recent → today → week → archive) with live passes glowing and older ones fading
- Adaptive moving-average smoothing on trails so older passes read as clean arcs rather than noisy dotting
- Time-window filter: scrub trails by recency — Live, 5m, 15m, 1h, 6h, 24h, 7d, 30d, or All — consistent across all three views
- Crash-safe persistence: atomic per-observation writes; retention configurable from 1 hour to unlimited (30-day default); brief signal drop-outs (< 5 min) rejoin the prior pass rather than splitting the trail
- Sector heatmap (u-center style): peak SNR per 5° × 5° sky cell, navy → purple → warm-red ramp — toggleable on the polar view
- GPS info: coordinates, Maidenhead grid locator, altitude, HDOP1, fix type, satellites used
- Celestial data: sun rise/set, solar noon, golden hour, civil twilight; moon phase, illumination, altitude, azimuth
- Signal analysis with diagnostics panel
- GPS Insights: on-device AI (Apple Foundation Models) summarises siting, signal quality, and reception trends from accumulated pass history — private, offline, no API key
- Basic Stratum 1 server on
localhost:12321, disciplined by the clock’s GNSS module — see setup below
- Conditions scrolled on the clock via WeatherKit; GPS-derived location, configurable update interval
- Serial monitor for raw NMEA and debug output
Warning
Proof-of-concept. Work in progress. Things may not work. Use the Mac app for the best experience.
Browser build of PCC for Chromium-based browsers (needs Web Serial). Open PCC Web · details in web/README.md · Swift ↔ JS mirror conventions in MAC_PARITY.md.
Can't do: NTP server, firmware/timezone updates, native map, WeatherKit, AI insights — each needs something browsers don't give.
git clone https://github.com/peterlewis/pcc.git
cd pcc
bash web/serve.sh # localhost:8765Web Serial works on localhost without HTTPS; any other host needs HTTPS.
Requires macOS 26+ and a Precision Clock Mk IV connected via USB.
git clone https://github.com/peterlewis/pcc.git
cd pcc
swift build
swift run PCCOr open Package.swift in Xcode and hit ⌘R.
Enable from the Time Server tab. The NTP server is a localhost convenience tool — there is no holdover oscillator, so if GPS fix is lost it falls back to system time without adjusting stratum.
Note
Not a production time source, and not intended as a network-facing server. Designed as a localhost source for chrony while GPS fix is held.
graph LR
A["GPS Satellites"] --> B["Mk IV GNSS"]
B -->|USB Serial| C["PCC NTP Server"]
C -->|UDP 12321| D["chrony"]
D --> E["System Clock"]
Pairing with chrony
Install chrony:
brew install chronyAdd to /opt/homebrew/etc/chrony.conf:
server 127.0.0.1 port 12321 iburst prefer
Start chrony:
sudo mkdir -p /var/run/chrony
sudo /opt/homebrew/sbin/chronyd -f /opt/homebrew/etc/chrony.confCheck status with chronyc tracking. You should see Stratum 1 with reference ID GPS.
[!IMPORTANT] chrony requires elevated privileges to discipline the system clock. PCC’s NTP server runs unprivileged on a non-standard port.
Protocol details
Commands are key = value\r\n over USB serial at 115200 baud. They take effect immediately but reset on power cycle unless saved to config.txt. The app disables NMEA output on connect so commands work reliably, and restores it on disconnect. See the Mk IV documentation for the full command reference.
[!CAUTION] Writing to config.txt overwrites the clock’s saved settings. PCC keeps a local backup on each write, but take care with manual serial commands.
| Dependency | Type | Purpose |
|---|---|---|
| ORSSerialPort | SPM | USB serial communication |
| globe.gl | Bundled | Interactive 3D globe view (MIT, served offline from Resources/Globe/) |
| three.js / three-globe | Bundled | Day/night ShaderMaterial and sphere layers (MIT, bundled transitively inside globe.gl.min.js) |
| NASA Blue Marble / Earth's City Lights | Bundled | Day and night Earth textures (public domain, redistributed via three-globe) |
| MapKit | Apple framework | Satellite world-map view (Apple Maps) |
| WeatherKit | Apple framework | Weather data |
Full license texts for bundled third-party code and assets are in THIRD_PARTY_LICENSES.md.
- Precision Clock Mk IV: official project documentation
- clock4: hardware design and firmware source
- Forum thread: discussion on the mitxela forum
Footnotes
-
HDOP (Horizontal Dilution of Precision) indicates the geometric quality of the satellite constellation. Lower is better; < 1.0 is excellent, > 5.0 is poor. ↩