PSI5¶

Peripheral Sensor Interface for automotive safety/chassis sensor connections.

Identity¶

Peripheral Sensor Interface for automotive safety/chassis sensor connections.

What This Protocol Teaches¶

• PSI5 lives at the boundary where measurement becomes network traffic.
• It teaches how to inspect current modulation, sensor slots, synchronous/asynchronous transfer without mistaking field extraction for meaning.
• It keeps observer inference separate from system truth.

Operational Context¶

PSI5 appears in automotive, sensor-link contexts and is modeled in the atlas at the physical, data-link layer(s). The binder treats it as an inspection surface: what evidence appears, what timing matters, and what outside authority is required before assigning meaning.

draft-structure-only: this is not yet a final-copy binder page. It has an atlas-grounded teaching hook and source notes, but still needs a stronger worked trace, page-specific ambiguity case, and reviewer-validated visual before promotion.

A Concrete Artifact¶

# synthetic PSI5 sensor slot
sync pulse -> slot 2 data=0x05a crc=ok

Synthetic offline sample for explanation; not a real operational trace or live-system instruction.

Worked Decode¶

1. Treat sync pulse -> slot 2 as timing-slot evidence for one synthetic sensor observation.
2. data=0x05a is a measurement-like payload but not an engineering unit without sensor authority.
3. crc=ok is integrity evidence for the observed slot, not sensor-health proof.
4. The key ambiguity is whether a missing slot is sensor silence, capture loss, or mode change.

Field Layout / Anatomy¶

Visual Model¶

Timing And Authority¶

Timing and authority depend on the sensor-interface role: scheduled, polled, arbitrated, transmitted, or logged evidence should not be read as the same kind of truth. Semantic authority is external to the raw artifact unless the artifact is itself a description or capture format; even then, provenance determines whether the description should be trusted.

Bytes rarely explain themselves. Name the source that defines meaning before naming engineering values: standard metadata, label table, DBC, PGN/SPN definition, object dictionary, register map, DID catalog, LDF, ARXML, channel metadata, or vendor profile.

Failure And Ambiguity¶

• A CRC-ok slot does not prove the sensed quantity is valid.
• Missing slots can be mode changes, sensor silence, or capture timing errors.
• Sensor-specific scaling is external authority.

Observer Lesson¶

A passive observer can usually infer artifact boundaries, repeated structure, cadence, missingness, and candidate state transitions. The observer usually cannot prove physical truth, application intent, complete system state, or engineering-unit meaning without semantic authority and timing provenance.

Python Model¶

No current runtime example is claimed for this draft page. Keep reader claims at the artifact and source level until a separate implementation plan adds a tested model.

Local Teaching Notes¶

The artifact and diagrams are synthetic teaching material. The page intentionally omits conformance timing tables, electrical design detail, proprietary configuration, and exhaustive standard behavior.

Source Confidence¶

Source confidence is medium for scope and terminology, with semantic claims limited to public metadata, public source notes, and synthetic teaching artifacts.

Source Notes¶

References¶

Public Sources¶

• PSI5 Consortium
• PSI5 specification information — protocol-consortium specification context.