A Garmin Connect IQ watch app for polar alignment on the Forerunner 255 family
(fr255, fr255s, fr255m, and fr255sm) and Forerunner 965 (fr965).
It acquires or edits an observing location, reviews atmospheric inputs,
calculates observer-corrected Polaris alignment values, and presents a live
dark-site display. The persisted Reticle selector offers the Generic numerical
result, the full iOptron graphic, or the enlarged inner-only Sifo graphic. Both
graphics retain live Polaris placement, clock/offset readouts, and warnings.
On iOptron and Sifo Displays, physical UP immediately enters a transient 6× view centered on the live green Polaris marker; physical DOWN restores the normal view. The magnified reticle artwork is clipped to the physical display edge, all text is hidden, and a full-screen green crosshair marks the physical center for precise alignment. The state resets on Display entry, recalculation, an invalid marker, or return from Actions. Generic and touch wake-only behavior are unchanged; SELECT/BACK retain their existing actions.
- Garmin Connect IQ SDK managed by Garmin SDK Manager
- A signing key at
~/Library/Application Support/Garmin/ConnectIQ/developer_key.der - GNU Make
- ImageMagick (
magick) when regenerating the launcher icon - uv when checking, regenerating, or updating IERS data
The Makefile reads the active SDK from ~/Library/Application Support/Garmin/ConnectIQ/current-sdk.cfg. Override DEVELOPER_KEY or DEVICE on the command line when needed.
make lint # check project XML formatting
make check-generated # verify checked-in IERS output without refreshing data
make generate-iers # regenerate IERS source from the checked-in snapshot
make update-iers # explicitly download and replace the IERS snapshot
make build # compile DEVICE (fr965 by default)
make DEVICE=fr255s build # compile one selected profile
make -j5 build-all # compile all five devices in parallel
make package # export one all-device PolarFinder.iq package
make simulator
make DEVICE=fr255 run # launch in the matching running simulator
make DEVICE=fr255s test # compile and run tests on one profile
make test-profiles # test representative 218, 260, and 454 profiles
make cleanmake simulator starts Garmin's simulator. Run it before make run or
make test. Single-device builds, runs, and tests honor DEVICE; artifacts are
written to bin/<device>/PolarFinder-<device>.prg, with compiler intermediates
isolated per device so parallel builds do not share generated state.
Test PRGs remain at bin/PolarFinder-tests-<device>.prg.
make test-profiles serializes all three profiles even when invoked with -j,
because MonkeyDo clients share one simulator.
make lint needs no install step; npx runs the exactly pinned Prettier and
XML plugin versions. Launcher PNGs are regenerated from
artwork/launcher-icon.svg when it changes: 65×65 for the 965 and dithered
40×40 family-qualified resources for the 64-color Forerunner 255 displays.
The astrometry calculation uses bundled, read-only reference data:
- Geoid: NGA EGM96 (
us_nga_egm96_15.tif) reduced to a global 15° lattice and bilinearly interpolated for MSL-to-ellipsoid height conversion. - Earth orientation: IERS Bulletin A
finals2000Aprediction rows, MJD 61292–61659 (2026-09-09–2027-09-11), with DUT1 and polar motion (xp,yp) interpolated at the fractional UTC MJD. Dates outside this interval are rejected; the final 30 days are marked as nearing expiry.
source/GeoidData.mc is handwritten; source/IersEopData.mc is generated from
the single checked-in data/iers/finals2000A-YYYY-MM-DD.txt snapshot. Ordinary
builds and CI do not refresh IERS data. See
Earth-data generation for ownership,
reproducible generation, and the explicit update procedure.
See CI trust and build contract for workflow triggers, signing
security, simulator tests, and build artifacts.
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