leviathan
44 lines
1.5 KiB
Markdown
44 lines
1.5 KiB
Markdown
# Subaru Protocol
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**Rust module:** `src/protocols/subaru.rs`
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**Reference:** `REFERENCES/ProtoPirate/protocols/subaru.c`
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## Overview
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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.
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## Timing
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| Parameter | Value | Notes |
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|-----------|---------|---------|
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| Short (1) | 800 µs | ±200 µs |
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| Long (0) | 1600 µs | ±200 µs |
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| Gap | 2800 µs | |
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| Sync | 2800 µs HIGH + 1600 µs LOW | |
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| Min bits | 64 | |
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## Encoding
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PWM: duration of HIGH = bit value (800 = 1, 1600 = 0); LOW 800 µs after each bit.
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## Frame Layout (64 bits = 8 bytes)
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- 4 bits button, 24 bits serial, counter-related in bytes 4–7 (decode_counter in code).
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## Decoder Steps
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1. **Reset** — Wait for long HIGH (preamble).
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2. **CheckPreamble** — Count 79 long pairs + 80th HIGH; then expect gap 2800 µs.
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3. **FoundGap** — Gap seen → look for sync (2800 HIGH, 1600 LOW).
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4. **FoundSync** — Sync seen → SaveDuration.
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5. **SaveDuration** — On HIGH: store duration, → CheckDuration. On end marker → return decode if 64 bits.
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6. **CheckDuration** — On LOW: pair (te_last, duration) → short–short = 1, long–long = 0; add bit, → SaveDuration.
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## Encoder
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Supported; builds preamble, gap, sync, then 64 PWM bits.
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## Frequencies
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433.92 MHz (and/or 315 MHz as in reference).
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