Internet Time Screen
August 9, 2026 · View on GitHub
External Flipper Zero app (.fap) that shows Swatch Internet Time (@000–@999)
alongside local time. Optional DCF77 sync corrects the Flipper RTC from an
external 77.5 kHz GPIO receiver. Stock-firmware compatible; no network or
firmware fork. DCF77 is not received via SubGHz (CC1101 cannot tune
77.5 kHz).
Requirements
- uFBT on the official release channel (local builds use SDK 1.4.3 / API 87.1)
- Flipper Zero with microSD card, USB data cable
- C11 host compiler (
cc) for unit tests - (Optional) DCF77 receiver module + ferrite antenna for live sync
Build
ufbt lint
ufbt
The FAP lands in dist/.
Host tests
./tests/run_host_tests.sh
Launch on device
ufbt launch
- Clock: Short OK / Back exits. Long OK opens settings.
- Settings: Up/Down select row; Left/Right change offset / Auto / Invert; OK on “Start sync” opens DCF77 sync; Back saves and returns.
- DCF77 Sync: listens on GPIO C0; Back cancels; Long OK runs a demo fixture that writes a known time through the same RTC path (no RF needed).
Configure UTC offset (15-minute steps) so Biel Mean Time is derived correctly from the Flipper RTC. Auto-sync (default On) starts sync once per app session when the last success is older than 12 hours.
DCF77 hardware
Wiring (confirm against your module silk; matches common Flipper DCF77 apps):
| Module | Flipper |
|---|---|
| VDD | pin 9 (3V3) |
| GND | pin 11 (GND) |
| PON / P (active-low) | GND when required |
| OUT / T | pin 16 (C0) |
Keep the ferrite rod ≥ ~10 cm from the Flipper and near a window. Reception across Europe is typically better at night.
Where to buy modules
- Reichelt — FREI DCF 77 receiver
- Shotech — DCF-1060N-MAS ± antenna
- CANADUINO / Universal Solder — Receiver V4
- Xtals — DCF77 single-frequency module
- Amazon.de — DCF77 module pack
- Amazon.com — 77.5 kHz module
Search “DCF77 module” / “77.5 kHz RCC” if a listing disappears. Prefer 1.1–3.3 V boards with a tuned ferrite antenna.
Note on firmware
Development acceptance may run on API-compatible custom firmware (e.g. RogueMaster) when API major/minor matches the release SDK. Catalog-oriented builds still target the official release SDK.