KAT/docs/subaru.md

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Subaru Protocol

Rust module: src/protocols/subaru.rs
Reference: REFERENCES/ProtoPirate/protocols/subaru.c

Overview

Subaru uses PWM: 800 µs HIGH = 1, 1600 µs HIGH = 0; LOW is 800 µs after each bit. 64 bits total (8 bytes MSB first: button(4) + serial(24) + counter-related). Preamble: 79 full 1600 µs pairs + 80th HIGH only; then gap 2800 µs, sync 2800 µs HIGH + 1600 µs LOW. Complex counter decoding from bytes 4–7.

Timing

Parameter	Value	Notes
Short (1)	800 µs	±200 µs
Long (0)	1600 µs	±200 µs
Gap	2800 µs
Sync	2800 µs HIGH + 1600 µs LOW
Min bits	64

Encoding

PWM: duration of HIGH = bit value (800 = 1, 1600 = 0); LOW 800 µs after each bit.

Frame Layout (64 bits = 8 bytes)

• 4 bits button, 24 bits serial, counter-related in bytes 4–7 (decode_counter in code).

Decoder Steps

1. Reset — Wait for long HIGH (preamble).
2. CheckPreamble — Count 79 long pairs + 80th HIGH; then expect gap 2800 µs.
3. FoundGap — Gap seen → look for sync (2800 HIGH, 1600 LOW).
4. FoundSync — Sync seen → SaveDuration.
5. SaveDuration — On HIGH: store duration, → CheckDuration. On end marker → return decode if 64 bits.
6. CheckDuration — On LOW: pair (te_last, duration) → short–short = 1, long–long = 0; add bit, → SaveDuration.

Encoder

Supported; builds preamble, gap, sync, then 64 PWM bits.

Frequencies

433.92 MHz (and/or 315 MHz as in reference).