Cadence from the CSC sensor #49

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opened 2026-08-31 17:25:15 +02:00 by robert · 0 comments

robert commented

2026-08-31 17:25:15 +02:00

(Migrated from git.butzei.de)

Goal

The Cycling Speed & Cadence characteristic already being parsed for wheel speed also carries crank revolutions. Exposing cadence is nearly free.

Acceptance criteria

Crank revolution count and last crank event time parsed from 0x2A5B
16-bit crank event-time wraparound handled, as for the wheel fields
Cadence in rpm computed and smoothed, and clamped to zero when the cranks stop
Sensors that report only wheel data, or only crank data, both handled without error
Cadence sent to the watch and shown as a ride data field
Cadence written into the recorded GPX using the standard TrackPointExtension
Wraparound and stop-detection covered by unit tests

Files

companion/.../sensors/CscClient.kt
watchapp/src/c/view_ride.c

Notes

See docs/DECISIONS.md D16.

## Goal The Cycling Speed & Cadence characteristic already being parsed for wheel speed also carries crank revolutions. Exposing cadence is nearly free. ## Acceptance criteria - [ ] Crank revolution count and last crank event time parsed from `0x2A5B` - [ ] 16-bit crank event-time wraparound handled, as for the wheel fields - [ ] Cadence in rpm computed and smoothed, and clamped to zero when the cranks stop - [ ] Sensors that report only wheel data, or only crank data, both handled without error - [ ] Cadence sent to the watch and shown as a ride data field - [ ] Cadence written into the recorded GPX using the standard TrackPointExtension - [ ] Wraparound and stop-detection covered by unit tests ## Files - `companion/.../sensors/CscClient.kt` - `watchapp/src/c/view_ride.c` ## Notes See docs/DECISIONS.md D16.