justin
6c1ee0c81d
obdcore additions (all standard SAE J1979, vehicle-agnostic, hardware-free tested): - obdservices.py: decode_vin (Mode 09), decode_readiness (Mode 01 PID 01 I-M monitors + MIL + DTC count, spark/diesel monitor sets), freeze-frame PID set. - link.py: ElmLink.read_vehicle_info (VIN/cal/ECU), read_readiness, read_freeze_frame. - trip.py: TripComputer (MAF-based MPG + trip totals) and PerformanceMeter (0-60 / 1/4-mile with launch detection). - mock.py: speed/MAF/readiness + service stubs for GUI mock mode. - tests/test_services.py: VIN, readiness bit decode, trip math, 0-60/quarter. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_016yT89n4zR4qbrySoSiEyZs
95 lines
3.9 KiB
Python
95 lines
3.9 KiB
Python
"""Standard OBD-II service decoders (vehicle-agnostic, no serial).
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Covers the generic SAE J1979 services OBDash exposes beyond live PIDs:
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- Mode 09 vehicle info (VIN, calibration IDs, ECU name)
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- Mode 01 PID 01 readiness / I-M monitors (+ MIL, DTC count)
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- Mode 02 freeze-frame (the standard PID set captured when a DTC set)
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These are pure functions over raw response byte lists so they can be unit
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tested without hardware; ElmLink wraps them with the actual reads.
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"""
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_VIN_CHARS = set("ABCDEFGHJKLMNPRSTUVWXYZ0123456789") # no I, O, Q
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def decode_vin(data):
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"""data: flattened response bytes for '0902' (49 02 <NODI> <17 ASCII>).
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Returns the 17-char VIN or None."""
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if 0x49 not in data:
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return None
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i = data.index(0x49)
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rest = data[i + 1:]
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# drop the service-PID (02) and number-of-data-items byte if present
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if rest and rest[0] == 0x02:
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rest = rest[2:]
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chars = "".join(chr(b) for b in rest if chr(b).upper() in _VIN_CHARS)
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return chars[-17:] if len(chars) >= 17 else (chars or None)
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def decode_ascii_block(data, svc_pid):
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"""Generic mode-09 ASCII payload (calibration IDs / ECU name) for svc_pid
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(e.g. 0x04, 0x0A). Returns a printable string or None."""
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if 0x49 not in data:
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return None
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i = data.index(0x49)
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rest = data[i + 1:]
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if rest and rest[0] == svc_pid:
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rest = rest[2:]
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s = "".join(chr(b) for b in rest if 0x20 <= b < 0x7F).strip()
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return s or None
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# Readiness monitor names by ignition type (SAE J1979 PID 01, bytes C/D bit map)
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_SPARK = ["Catalyst", "Heated Catalyst", "Evap System", "Secondary Air System",
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"A/C Refrigerant", "O2 Sensor", "O2 Sensor Heater", "EGR System"]
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_COMPRESSION = ["NMHC Catalyst", "NOx/SCR Aftertreatment", "-", "Boost Pressure",
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"-", "Exhaust Gas Sensor", "PM Filter", "EGR/VVT System"]
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_CONTINUOUS = [("Misfire", 0), ("Fuel System", 1), ("Components", 2)]
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def decode_readiness(data):
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"""data: 4 bytes [A,B,C,D] from Mode 01 PID 01. Returns a dict:
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{mil, dtc_count, ignition, monitors:[{name, ready}], ready_count, total}."""
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if len(data) < 4:
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return None
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a, b, c, d = data[0], data[1], data[2], data[3]
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compression = bool(b & 0x08)
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monitors = []
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# continuous monitors: B bits 0-2 supported, bits 4-6 = incomplete
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for name, i in _CONTINUOUS:
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if b & (1 << i):
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monitors.append({"name": name, "ready": not (b & (1 << (i + 4)))})
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# non-continuous: C bits = supported, D bits = incomplete
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names = _COMPRESSION if compression else _SPARK
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for i, name in enumerate(names):
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if name == "-":
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continue
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if c & (1 << i):
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monitors.append({"name": name, "ready": not (d & (1 << i))})
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ready = sum(1 for m in monitors if m["ready"])
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return {
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"mil": bool(a & 0x80),
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"dtc_count": a & 0x7F,
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"ignition": "compression" if compression else "spark",
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"monitors": monitors,
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"ready_count": ready,
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"total": len(monitors),
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}
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# Standard PID set read from the freeze frame (Mode 02, frame 0).
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# (key, pid hex, nbytes, decoder(bytes)->value, unit)
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FREEZE_PIDS = [
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("Fuel System Status", "03", 2, lambda b: b[0], ""),
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("Engine Load", "04", 1, lambda b: round(b[0] * 100 / 255), "%"),
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("Coolant Temp", "05", 1, lambda b: b[0] - 40, "C"),
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("Short Term Fuel Trim", "06", 1, lambda b: round(b[0] * 100 / 128 - 100), "%"),
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("Long Term Fuel Trim", "07", 1, lambda b: round(b[0] * 100 / 128 - 100), "%"),
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("Intake MAP", "0B", 1, lambda b: b[0], "kPa"),
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("Engine RPM", "0C", 2, lambda b: round((b[0] * 256 + b[1]) / 4), "rpm"),
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("Vehicle Speed", "0D", 1, lambda b: b[0], "km/h"),
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("Intake Air Temp", "0F", 1, lambda b: b[0] - 40, "C"),
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("MAF", "10", 2, lambda b: round((b[0] * 256 + b[1]) / 100, 1), "g/s"),
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("Throttle Position", "11", 1, lambda b: round(b[0] * 100 / 255), "%"),
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]
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