ECU simulation

Multi-ECU simulation lets students observe a virtual vehicle network without wiring harnesses. @embedded32/sim provides profiles and a runner; @embedded32/tools exposes them via CLI.

Architecture

flowchart TB
  TOOLS[embedded32-tools simulate]
  RUN[SimulationRunner]
  PROF[Vehicle profile]
  ECU1[Engine ECU]
  ECU2[Transmission ECU]
  ECU3[Diagnostic tool]
  BUS[Virtual CAN bus]
  J1939[@embedded32/j1939 decode]
  TOOLS --> RUN
  RUN --> PROF
  PROF --> ECU1
  PROF --> ECU2
  PROF --> ECU3
  ECU1 --> BUS
  ECU2 --> BUS
  ECU3 --> BUS
  BUS --> J1939
  J1939 --> TOOLS

Basic truck profile

Command:

npx embedded32-tools simulate vehicle/basic-truck

Typical actors:

Actor	Role	Teaching focus
Engine ECU	Torque, speed, temperatures	Periodic broadcast PGNs
Transmission ECU	Gear, driveline status	Multi-node bus traffic
Diagnostic tool	DM1-style observation	Diagnostics lab prep

Simulation tick

sequenceDiagram
  participant RUN as SimulationRunner
  participant ECU as ECU actor
  participant CAN as Virtual bus
  participant OUT as Terminal decode
  loop each simulation step
    RUN->>ECU: tick(state)
    ECU->>CAN: emit frame(s)
    CAN->>OUT: decodeJ1939 → log line
  end

Programmatic use

From TypeScript (after npm run build):

import { SimulationRunner } from '@embedded32/sim';

const runner = new SimulationRunner();
await runner.loadProfile('vehicle/basic-truck');
await runner.start();
// ... observe or hook frames
await runner.stop();

Exact API names may vary - see generated API docs or package exports.

Extending profiles

Instructors can add profiles under the sim package (maintainer workflow):

Define ECU actors with periodic transmit lists
Register profile id vehicle/<name>
Document expected PGN output for grading rubrics

Hardware bridge path

Simulation output can feed a bridge for MQTT/Ethernet labs:

flowchart LR
  SIM[sim runner]
  CAN[virtual CAN]
  BR[bridge]
  MQTT[MQTT broker]
  SIM --> CAN --> BR --> MQTT

Limitations

Simplified vehicle physics - not a full vehicle dynamics model
Fixed timing - not wall-clock synchronized across machines without bridge
Profile catalog is small in v1.0 - grows in v1.1 labs