scope-clock

A rewrite of the SCTV Scope Clock firmware as a thin vector-rendering client with an NTP-disciplined RTC, plus an ESP32-S3 Wi-Fi bridge (M5Stack AtomS3U).

Derivative of nixiebunny/SCTVcode (David Forbes / Cathode Corner), GPL-2.0-or-later.

Layout

scope-clock/
├─ scope-clock.code-workspace   ← open this in VS Code (multi-root)
├─ shared/protocol.h            ← single source of truth for the wire protocol
├─ display-teensy/              ← the thin client (Teensy 3.6 + DS3232 + CRT)
└─ bridge-esp32/                ← Wi-Fi bridge (ESP32-S3 / AtomS3U)

Prerequisites

1. VS Code + the PlatformIO IDE extension.
2. Teensy flashing: install Teensyduino; on Linux add the 49-teensy.rules udev rules.
3. ESP32 needs nothing extra — the espressif32 platform is fetched by PlatformIO.

Build

Open the workspace, then per project use the PlatformIO toolbar (Build ✓ / Upload →), or the CLI:

cd display-teensy && pio run            # build
cd display-teensy && pio run -t upload   # flash (board plugged in)

cd bridge-esp32   && pio run
cd bridge-esp32   && pio run -t upload

Status

The roadmap is complete and running on hardware. Forty-seven built-in faces draw from the DS3232; the ESP32 bridge disciplines the RTC from NTP over a USB-host link with no wiring; the host can push arbitrary vector scenes, banners, and face templates that keep telling the time on their own; and the clock appears in Home Assistant over MQTT discovery with controls, diagnostics and device triggers.

The knob walks the fifteen families — dials, digital, solids, curves, motion, wireframes, the sky and the rest — and the button changes the style within one.

Every face

Rendered by compiling the firmware's own vector.cpp against a fake DAC and integrating the dots with a decay, which is what phosphor does — so these are the real geometry and the real beam path, not mock-ups, but they are renders rather than photographs of the tube. Each clip runs three seconds at the speed the clock runs, and the second hand is really ticking. Faces drawn from pushed data show sample data.

hands Analog	numbers Analog	tickdial Analog	orbit Analog	sector Analog	digital Digital
datetime Digital	wordclock Digital	binary Digital	tetra Solids	cube Solids	octa Solids
icosa Solids	dodeca Solids	tesseract Solids	torus Solids	lissajous Curves	harmonograph Curves
spirograph Curves	rose Curves	lorenz Curves	starpoly Curves	starfield Motion	tunnel Motion
midiscope MIDI	midichord MIDI	matrix Effects	nowplaying Data	gauges Data	teapot Wireframes
sphere Wireframes	knot Wireframes	mobius Wireframes	helix Wireframes	atom Science	solar Sky
moon Sky	weather Sky	pong Games	life Games	trailclock Extra	ticker Extra
worldclock Extra	asteroids Arcade	constell Stars	starglobe Stars

Regenerate with python3 tools/gen_gallery.py after adding a face. Two further faces are driven live over USB-MIDI on the front jack: midiscope plots the lower note against the upper, so an interval draws its own frequency ratio the way an oscilloscope in X-Y mode does (a fifth is the 3:2 figure), and midichord shows the sounding pitch classes as a shape on the chromatic wheel. tools/play_midi.py --demo walks the intervals if there is no keyboard to hand.

Without the bridge

The clock is autonomous: all 46 faces live on the Teensy and render from the DS3232, the knob and button work locally, and nothing in boot or the render loop waits on the link. Unplug the bridge and it keeps time and keeps drawing.

Hold the knob's button for 2.5 seconds for the settings menu — past the 0.8s that enters size mode. Turn to move, tap to select: set time, set date, face size, typeface, burn-in drift, info, exit. The editors take three fields each — turn to change, tap for the next, the last tap commits — and an edit you walk away from expires after 30s without changing anything.

A setting is in that menu if changing it means something with no bridge attached. Wi-Fi, MQTT and the rest stay on the config page.

The config page carries a link trace: every frame between the two MCUs in both directions, decoded, newest last. Both arrows moving means the link is healthy; only inbound moving is the one-way failure this hardware is prone to, and it shows there before any symptom reaches the tube.

The config page also has centring, which shifts the whole image on top of the trimmer pots inside the case, and a target face of concentric rings to set it against. The outer ring sits on the tube's usable radius, so it should touch the glass all the way round when the picture is centred.

What the bridge adds is NTP (and therefore summer time, which the device never reasons about), persistence for the per-face sizes and the other settings, the five host-fed faces — weather, ticker, worldclock, nowplaying, gauges — and everything networked: MQTT, Home Assistant, pushed scenes and the config page.

The bridge also serves a config page at http://scope-clock-bridge.local/ (guarded by the OTA password) for setting Wi-Fi, MQTT and timezone without rebuilding.

phase	what	state
P0	render engine: vectors, stroke font, RTC	done
P1	framed link, real CRC, encoder/button, NTP SET_TIME	done
P2	PushList + Banner — true thin client	done
P3	MQTT / Home Assistant on the bridge	done
P4	face templates, web config	done

Flashing: pio run -t upload in display-teensy/, and pio run -e atoms3u_ota -t upload in bridge-esp32/ (over Wi-Fi). Copy bridge-esp32/.env.example to .env and fill it in first.

Licence

Copyright (C) 2026 Kayden D'Mello. Derived from SCTVcode, Copyright (C) 2008-2022 David Forbes (Cathode Corner).

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. It is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See LICENSE for the full text.