motec_m1

Overview

motec_m1 decodes a MoTeC M1 ECU’s general CAN broadcast into typed telemetry, one topic per frame. It reads the raw frames can_bridge publishes, decodes them with the generated parser for dbcs/motec/Motec_M1_Rev3.dbc, and publishes 32 topics under nodes/motec_m1/. It needs can_bridge running with the M1 on its can0 channel. It does not talk to the ECU, and it publishes a subset of the DBC’s signals, the ones the schema comments call “key signals for dashboard use”.

Running it

The node takes only command-line options, and the only one is --help. The frame topic and every output topic are fixed in the source.

./build/nodes/motec_m1/motec_m1

Option	Meaning
-s, --source	Zenoh key carrying CAN frames (default vehicle/can0/rx)
-p, --prefix	Key prefix for this node’s topics (default nodes/motec_m1)
--debug	Debug logging
-h, --help	Print usage and exit

Logging is at debug level from the start.

Running without hardware

There is no M1 simulator in the tree. Replay a recorded trace through can_bridge’s trc: channel (see configs/can_bridge/replay.yaml) or a bag recording, or hand-make frames with inspect publish. None of the M1 messages is multiplexed, so a single frame is enough for any topic that comes from one id:

./build/nodes/inspect/inspect echo nodes/motec_m1/engine_air -n 1 &
# 3000 rpm, 100.0 kPa, 25.0 C, 50.0 % throttle, big-endian
./build/nodes/inspect/inspect publish vehicle/can0/rx --schema CanFrame \
    --data '{"id":1600,"len":8,"data":[11,184,3,232,0,250,1,244]}'

Topics

Every topic is under nodes/motec_m1/. The M1 transmits at base 0x640 (1600) with the auxiliary blocks at 0x6A0; the ids below are what the DBC names and are decimal in CanFrame.

Topic	Schema	Id	Contents
engine_air	MotecM1EngineAir	0x640	Engine speed, MAP, inlet manifold temperature, throttle position
fuel_status	MotecM1FuelStatus	0x641	Fuel volume, mixture aim, fuel pressure, injector duty, engine efficiency
throttle_timing	MotecM1ThrottleTiming	0x642	Pedal, engine load, ignition and fuel timing
cuts_oil_pressure	MotecM1CutsAndOilPressure	0x644	Ignition and fuel cut counts and averages, cylinder 1 pulse width, cut and timing states, oil pressure
boost_status	MotecM1BoostStatus	0x645	Boost pressure and aim, actuator duty, gear lever force
inlet_cam, exhaust_cam	MotecM1InletCam, MotecM1ExhaustCam	0x646, 0x647	Cam aim, both banks’ position and duty
wheel_speeds	MotecM1WheelSpeeds	0x648	Four wheel speeds in km/h
temperatures	MotecM1Temperatures	0x649	Coolant, oil, fuel, ambient and airbox temperature, ECU battery volts, fuel used
environment	MotecM1Environment	0x64A	Exhaust temperature, average load, ignition rev limit, ambient pressure
runtime_warnings	MotecM1RuntimeWarnings	0x64C	Run time, ECU up time, warning source and eight warning flags
states	MotecM1States	0x64D	Fuel pump, engine, launch, anti-lag, limiter, boost, cut, overrun, knock, purge, closed-loop and throttle states, gear
diagnostics	MotecM1Diagnostics	0x64E	Launch, anti-lag, boost and closed-loop diagnostics, and the switch inputs
totals	MotecM1Totals	0x64F	Run hours, closed-loop trims, gearbox temperature, tank level
driver_controls	MotecM1DriverControls	0x650	Rotaries 1..6, switches 1..8
exhaust	MotecM1Exhaust	0x651	Lambda overall and per bank, exhaust temperature per bank
fuel_secondary	MotecM1FuelSecondary	0x652	Secondary injector contribution, timing and duty
pressures	MotecM1Pressures	0x655	Brake front and rear, coolant, power steering
flows	MotecM1Flows	0x656	Steering angle, inlet and airbox mass flow, fuel flow
injector_pressures	MotecM1InjectorPressures	0x657	Primary and secondary injector pressure, gearbox shaft speeds
vehicle_dynamics	MotecM1VehicleDynamics	0x658	Lateral, longitudinal and vertical g, yaw rate
lap_timing	MotecM1LapTiming	0x65B	Lap time, running lap time, lap number and distance
diff_rotary	MotecM1DiffAndRotary	0x65C	Front differential temperature, rotaries 7 and 8
brake_temperatures	MotecM1BrakeTemperatures	0x65D	Four brake temperatures
exhaust_pressures	MotecM1ExhaustPressures	0x65E	Exhaust pressure per bank, crankcase pressure, alternator current
thresholds_limits	MotecM1ThresholdsAndLimits	0x65F	Knock threshold, logging used, pit speed limit
aux_outputs, aux_output5	MotecM1AuxOutputs, MotecM1AuxOutput5	0x6A0, 0x6A1	Auxiliary output duties 1..4, and 5

The five temperatures in temperatures are Int16 as of 2026-09-15. They were Int8, which wrapped anything above 127 C negative, so a recording made before then misreads those fields.

Four topics are built from a pair of frames and publish only when both have arrived since the last publish:

Topic	Schema	Ids	Contents
knock_levels_1_12	MotecM1KnockLevels1to12	0x643 + 0x659	Knock level for cylinders 1..12
ignition_trim_1_12	MotecM1IgnitionTrim1to12	0x64B + 0x65A	Ignition trim in degrees for cylinders 1..12
fuel_direct_all	MotecM1FuelDirectAll	0x653 + 0x654	Direct injection fuel pressure loop, both banks
turbo	MotecM1Turbo	0x6A6 + 0x6A7	Turbo speed, inlet and outlet temperature and inlet pressure, both banks

The node subscribes to vehicle/can0/rx with schema CanFrame. A frame shorter than eight bytes is rejected rather than decoded with padding.

Health

The node publishes nodes/motec_m1/health (NodeHealth) once a second, and at once whenever a check changes:

Check	Degraded when
can_rx	no CAN frame of any kind has arrived for a second: the bus is quiet, or the node is subscribed to the wrong key
decoded	frames are arriving but none of them has been one of this node’s messages for two seconds

inspect health prints them. The node exits cleanly on SIGINT or SIGTERM, so a monitor reads a deliberate stop as exited rather than as a crash.

Services

None.

Tests

ctest --test-dir build -L motec_m1

Target	Labels	Proves
motec_m1_test_messages	motec_m1 unit	Which signal becomes which field, for one message of each shape and for all four messages assembled from two frames – where a field taken from the wrong frame is otherwise invisible.

The mapping lives in its own library (motec_m1_messages.h) so it can be tested without a bus: the generated decoder is checked against cantools and the schema round-trips itself, but the wiring between the two is only checked here.

Troubleshooting

All 32 topics are advertised and none publishes. Advertisement happens at startup, so inspect list only says the node is up. inspect hz vehicle/can0/rx says whether frames arrive; none means can_bridge is not running, or the M1 is on a channel whose topic is not vehicle/can0/rx, and this node cannot be redirected. Frames arriving but none between 1600 and 1703 means the M1’s CAN transmit template is at another base address, or the general broadcast is not enabled in its package; only base 0x640 is decoded.

Most topics publish, but one of the paired ones never does. The pair waits for both of its ids. An M1 package that transmits 0x643 but not 0x659, say, gives no knock_levels_1_12 at all rather than half of one. inspect echo vehicle/can0/rx -n 200 and check both ids appear.

The bus is empty and vehicle/can/status shows error counters climbing or the channel bus-off. That is a bit-rate mismatch presenting as silence. can_bridge’s shipped config runs can0 at 500 kbit/s; the M1’s rate is set in its package, and 1 Mbit/s is the common MoTeC choice.

A topic publishes at the wrong rate for a dashboard. Each topic publishes once per frame, at whatever rate the M1 transmits that id; the node neither throttles nor resamples. Change the transmit rate in the M1 package, or let the widget decide how often to redraw.