Salat Clock for Flipper Zero

An offline five-prayer clock for Flipper Zero, built as a proof of concept for Momentum firmware.

Salat Clock calculates Fajr, Dhuhr, Asr, Maghrib, and Isha directly on the device from its RTC date and an editable latitude, longitude, altitude, and fixed UTC offset. Optional reference pages live on the microSD card, so their wording can be revised without rebuilding the FAP.

Features

• Five daily prayer times calculated without a network connection
• Flipper RTC date, with an optional date override for testing
• Local config.txt using latitude, longitude, altitude, and UTC offset
• SD-card Arabic, English, and deeper reference pages
• Small, fixed memory footprint suitable for the Flipper Zero
• 10 by 10 monochrome launcher icon

Install on Momentum

Download the FAP and SD-card package from the latest GitHub release, or build the source against Momentum with uFBT:

ufbt update --index-url=https://up.momentum-fw.dev/firmware/directory.json
ufbt

Copy the generated FAP to /ext/apps/Tools/salat_times.fap, then copy the contents of sd_card/ to the root of the Flipper's microSD card. Edit /ext/apps_data/salat_times/config.txt for the local position:

lat=-37.8676
lon=144.9810
alt=22
tz=10

tz is a fixed UTC offset. Update it when daylight-saving time changes. Optional year, month, and day keys override the Flipper RTC for testing.

On the main screen, Up opens the Arabic reference, OK opens English, and Down opens the deeper reference. Left and Right move between pages; Back returns home or exits.

Calculation model

The app uses NOAA/Spencer solar geometry for sunrise, sunset, solar noon, declination, and equation of time. Its dawn and nightfall offsets follow the project's relative-hour quadratic model, while Dhuhr is solar noon, Asr is RH9, and Maghrib is sunset.

This is a practical pocket proof of concept, not a substitute for an authoritative local timetable or religious guidance. High-latitude dates without valid solar events fail visibly instead of fabricating a result.

Verification

Run the portable calculation test without the Flipper SDK:

cc -std=c11 -Wall -Wextra -Werror -I. \
  tests/test_core.c salat_calc.c -lm -o /tmp/salat_core_test
/tmp/salat_core_test

See BUILD_VERIFICATION.md for the SDK and physical-device status of the published proof of concept.

License

Source code is available under the Mozilla Public License 2.0.