Section 1 backend: VIN/Mode-09, readiness monitors, freeze-frame, trip/perf
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
This commit is contained in:
@@ -172,6 +172,41 @@ class ElmLink:
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data = self._bytes(lines)
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return 0x44 in data or ("OK" in "".join(lines).upper())
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# -- standard OBD services (Mode 09 / 01-01 / 02) --
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def read_vehicle_info(self, timeout=2.0):
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"""Mode 09: VIN + calibration IDs + ECU name. Returns a dict."""
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from . import obdservices as svc
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vin = svc.decode_vin(self._bytes(self.cmd("0902", timeout=timeout)))
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cal = svc.decode_ascii_block(self._bytes(self.cmd("0904", timeout=timeout)), 0x04)
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ecu = svc.decode_ascii_block(self._bytes(self.cmd("090A", timeout=timeout)), 0x0A)
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return {"vin": vin, "calibration": cal, "ecu_name": ecu}
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def read_readiness(self, timeout=1.0):
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"""Mode 01 PID 01: MIL, DTC count, and I-M readiness monitors."""
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from . import obdservices as svc
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data = self.read_m01("01", 4, timeout=timeout)
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return svc.decode_readiness(data) if data else None
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def read_freeze_frame(self, timeout=0.6):
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"""Mode 02: the DTC that set the freeze frame + the standard PID snapshot."""
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from . import obdservices as svc
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out = {"dtc": None, "values": []}
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d = self._bytes(self.cmd("0202", timeout=timeout))
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if 0x42 in d:
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r = d[d.index(0x42) + 2:] # after '42 02'
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if len(r) >= 2 and (r[0] or r[1]):
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out["dtc"] = decode_dtc(r[0], r[1])
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for name, pid, nbytes, dec, unit in svc.FREEZE_PIDS:
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dd = self._bytes(self.cmd(f"02{pid}00", timeout=timeout))
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if 0x42 in dd:
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payload = dd[dd.index(0x42) + 3:dd.index(0x42) + 3 + nbytes]
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if len(payload) == nbytes:
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try:
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out["values"].append((name, dec(payload), unit))
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except Exception:
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pass
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return out
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def close(self):
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try:
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self.ser.close()
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+23
-2
@@ -42,10 +42,18 @@ class MockLink:
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return None # everything else: no response
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def read_m01(self, pid, nbytes, timeout=0.6):
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if pid == "0C": # RPM 0 at rest
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return [0x00, 0x00]
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if pid == "0C": # RPM ~750 idle
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v = 750 * 4
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return [(v >> 8) & 0xFF, v & 0xFF]
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if pid == "05": # ECT 82C
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return [122]
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if pid == "0D": # speed 48 km/h
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return [48]
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if pid == "10": # MAF 12.0 g/s
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v = 1200
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return [(v >> 8) & 0xFF, v & 0xFF]
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if pid == "01": # readiness: MIL off, 0 DTCs, mixed monitors
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return [0x00, 0x07, 0x61, 0x20]
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return None
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def read_atrv(self, timeout=0.8):
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@@ -58,5 +66,18 @@ class MockLink:
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def clear_dtcs(self):
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return True
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def read_vehicle_info(self, timeout=2.0):
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return {"vin": "1FMZU73E12ZA12345", "calibration": "JR3A-12A650-BCD",
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"ecu_name": "ECM-EngineControl"}
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def read_readiness(self, timeout=1.0):
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from . import obdservices as svc
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return svc.decode_readiness([0x00, 0x07, 0x61, 0x20])
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def read_freeze_frame(self, timeout=0.6):
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return {"dtc": "P0148",
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"values": [("Engine RPM", 240, "rpm"), ("Coolant Temp", 33, "C"),
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("Engine Load", 18, "%"), ("Vehicle Speed", 0, "km/h")]}
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def close(self):
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pass
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@@ -0,0 +1,94 @@
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"""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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+119
@@ -0,0 +1,119 @@
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"""Trip computer + performance timers (computed from live data, no serial).
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TripComputer estimates fuel economy and trip totals from vehicle speed (km/h)
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and MAF (g/s) -- the same MAF-based estimate Torque/etc. use. PerformanceMeter
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measures 0-60 mph and 1/4-mile times, auto-detecting a launch from a near-stop.
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Both are fed time-stamped samples and are unit tested without hardware.
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"""
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KMH_PER_MPH = 1.609344
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GAS_AFR = 14.7 # stoichiometric air:fuel for gasoline
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GAS_G_PER_GAL = 2835.0 # ~6.25 lb/gal
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def _gph(maf_gps, afr=GAS_AFR, g_per_gal=GAS_G_PER_GAL):
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return (maf_gps / afr) * 3600.0 / g_per_gal
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class TripComputer:
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def __init__(self, afr=GAS_AFR, g_per_gal=GAS_G_PER_GAL):
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self.afr, self.g_per_gal = afr, g_per_gal
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self.reset()
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def reset(self):
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self.dist_km = 0.0
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self.fuel_gal = 0.0
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self.moving_s = 0.0
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self.elapsed_s = 0.0
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self._t = None
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def update(self, t, speed_kmh, maf_gps):
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if self._t is None:
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self._t = t
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return
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dt = t - self._t
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self._t = t
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if dt <= 0 or dt > 5: # ignore gaps / first sample
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return
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self.elapsed_s += dt
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if speed_kmh:
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self.dist_km += speed_kmh * dt / 3600.0
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if speed_kmh > 1.0:
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self.moving_s += dt
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if maf_gps:
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self.fuel_gal += _gph(maf_gps, self.afr, self.g_per_gal) * dt / 3600.0
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def instant_mpg(self, speed_kmh, maf_gps):
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if not speed_kmh or not maf_gps:
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return 0.0
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gph = _gph(maf_gps, self.afr, self.g_per_gal)
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return (speed_kmh / KMH_PER_MPH) / gph if gph > 0 else 0.0
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def avg_mpg(self):
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miles = self.dist_km / KMH_PER_MPH
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return miles / self.fuel_gal if self.fuel_gal > 0 else 0.0
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def stats(self):
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return {
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"distance_mi": round(self.dist_km / KMH_PER_MPH, 2),
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"fuel_gal": round(self.fuel_gal, 3),
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"avg_mpg": round(self.avg_mpg(), 1),
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"elapsed_s": round(self.elapsed_s, 1),
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"moving_s": round(self.moving_s, 1),
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}
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class PerformanceMeter:
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"""0-60 mph and 1/4-mile timers. A run starts when the car pulls away from a
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near-stop and ends at the 1/4 mile or when it stops; best times are kept."""
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QUARTER_M = 402.336
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def __init__(self):
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self.best_0_60 = None
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self.best_quarter = None
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self.last_0_60 = None
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self.last_quarter = None
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self._reset_run()
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def _reset_run(self):
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self._running = False
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self._t0 = None
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self._dist_m = 0.0
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self._last_t = None
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self._stop_t = None
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self._did60 = False
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def update(self, t, speed_kmh):
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if speed_kmh is None:
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return
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mph = speed_kmh / KMH_PER_MPH
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if not self._running:
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if mph < 1.0:
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self._stop_t = t # parked, ready to launch
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elif self._stop_t is not None:
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self._running = True # launch detected
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self._t0 = self._stop_t
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self._dist_m = 0.0
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self._last_t = t
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self._did60 = False
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return
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dt = t - self._last_t
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self._last_t = t
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if dt <= 0 or dt > 5:
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self._reset_run()
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return
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self._dist_m += (speed_kmh / 3.6) * dt
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if mph >= 60 and not self._did60:
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self._did60 = True
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self.last_0_60 = round(t - self._t0, 2)
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if self.best_0_60 is None or self.last_0_60 < self.best_0_60:
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self.best_0_60 = self.last_0_60
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if self._dist_m >= self.QUARTER_M:
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self.last_quarter = round(t - self._t0, 2)
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if self.best_quarter is None or self.last_quarter < self.best_quarter:
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self.best_quarter = self.last_quarter
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self._reset_run()
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elif mph < 1.0:
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self._reset_run()
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