MS43 Emulator

Run a Siemens MS43 bin from power-on on your PC, drive it, and see what the ECU does, before you flash it.

A cycle-counted emulator of the MS43's Infineon C167CR and its board, with an engine and a car around it.
It runs the real firmware, unmodified: stock MS430069-family software, MS43X001, or your own patched bin.

What it does · Quick start · Drives and checks · Compare two bins · Build and test · Reference

Important

A pass from the emulator means the firmware did what its own logic says, on the inputs a drive feeds it. It is not an engine-safety clearance: there is no combustion, knock or octane model, no measured fuelling and no thermal model. Every report says so (physical calibration safety: NotEvaluated). Judge a calibration on the car, with the right instruments.

What it does

• Boots the real firmware. The boot block, the checksum tasks, the monitoring-module handshake and the scheduler run as on the ECU. A key-off runs the after-run, writes the EEPROM and drops the main relay; the next key-on reads it back.
• Runs an engine and a car around it. A warm engine idles on the firmware's own target. Every spark, dwell and injection is the firmware's decision, logged with the crank angle and the values behind it.
• Plays drives. A short text file says what the driver does: key on, crank, idle, pull in 4th, lift, clutch in, A/C on, a fault. Drives run across power cycles, from a blank or a seasoned EEPROM.
• Checks the run. 16 checks look at crashes, resets, the scheduler, the outputs and the engine, and every fault code is explained or flagged. The verdict is pass, fail or incomplete.
• Talks on the K-line. A tester on ASC0 plays the DS2 session of MS43 Tuner, so logging and live tuning are tested against the real firmware.
• Compares two bins. Both bins go through the same drives, and the report lists their calibration, code and behaviour differences, down to the cylinder and the crank degree.

It was built to develop MS43 Tuner and the live-tuning overlay (MS43X001_CUSTOM): every overlay version ran here, on scripted drives, before it went near a car.

What you need

For	You need
Building	The .NET 10 SDK. Developed on Windows; it has no Windows-only code that we know of, but other systems are untested
Running	An MS43 bin (512 KiB). No bin and no firmware is included: bring your own
Compare names	Optionally, the MS43X001 XDF from the MS4X project, to name constants

It has been developed and checked mostly on MS43X001 (M54B25) and the car file it runs on. The checks that read the firmware's RAM know MS43X001's layout; on stock software those checks report incomplete rather than guess.

Quick start

The Releases page has ms43sim ready to run for Windows and Linux (x64, no .NET needed), with the standard drives next to it: unzip, then run ms43sim boot my.bin in that folder. To build it yourself:

git clone https://github.com/raph559/MS43_EMULATOR.git
cd MS43_EMULATOR
dotnet build -c Release Ms43Sim.sln

Then, with your bin at my.bin:

# Boot it: does it reach the scheduler?
dotnet src/Ms43Sim.Cli/bin/Release/net10.0/ms43sim.dll boot my.bin

# Start the engine and idle for a minute
dotnet src/Ms43Sim.Cli/bin/Release/net10.0/ms43sim.dll run my.bin --engine warm-idle

# Run the seven standard drives, six at a time
dotnet src/Ms43Sim.Cli/bin/Release/net10.0/ms43sim.dll check my.bin --jobs 6

Each command writes a folder under runs/: a Markdown report, events.csv (every output change), trace.csv (the firmware's variables every 100 ms), the EEPROM at the end and an assessment.json. The exit code is the verdict: 0 pass, 1 fail, 4 incomplete.

Drives and checks

A drive is plain text, one step per line: how many seconds, then what happens.

# The overrun fuel cut: a lift at 110 km/h in 4th, then the clutch in.
drive overrun
start seasoned
set coolant=90 oil=90 intake=33 ambient=20
3 on
1.5 crank rpm=200
6 idle
6 drive gear=4 speed=25..110 pedal=30
10 drive gear=4 speed=110..30 pedal=0    # the lift: the overrun fuel cut
2 drive gear=4 speed=30 pedal=0 clutch=1
5 idle

drives/ holds the seven standard drives (warm start, cold start, idle, part load, full load, overrun, key cycle) and the overlay's own sets: the live-tuning session and its abuse, pops, the downshift blip and the map watch. The drive file format, the options and the checks are in the reference.

Compare two bins

dotnet src/Ms43Sim.Cli/bin/Release/net10.0/ms43sim.dll compare stock.bin tuned.bin --jobs 6

compare runs both bins through the same drives and reports:

• calibration: every table, axis and constant with changed bytes;
• code: the changed byte ranges, with a listing;
• behaviour: where the two runs part, per cylinder for sparks and injections and per sample for the trace, with the operating point there (rpm, air mass, coolant, speed, the drive's line).

Tolerances are printed in every report. Read a code change on a drive in gear with care: any change in the program's timing shifts the phase of the controllers, and the report says so.

Build and test

dotnet build -c Release Ms43Sim.sln
dotnet test Ms43Sim.sln --filter "Category!=StandardDrives"

There are about a thousand xUnit tests: the instruction set against the manuals, every peripheral, board device and engine plant, the K-line, drives, checks, the compare and the live-tuning overlay. The tests that boot or drive real bins read them from a bins/ folder you point to with MS43_BINS_ROOT, and check each one's SHA-256; those bins are not published, so without them only the bin-free tests can run. The StandardDrives category (the long drives) takes about ten minutes more.

On a desktop PC the emulator runs at around 110 to 130 million C167 cycles a second, about 5 times faster than the real ECU; check of seven drives takes about half a minute with --jobs 6.

Layout

Path	Content
src/Ms43Sim.Core/	The image tools, CPU, memory map, peripherals, board, engine and car, K-line, drives, checks, runners and the compare
src/Ms43Sim.Cli/	The ms43sim command: boot, run, check, compare, decode
tests/Ms43Sim.Tests/	xUnit tests, and the overlay builds as Intel HEX fixtures
drives/	The standard drives and the overlay's drives
tools/	Python helpers for the C167 manuals and the decoder
HARDWARE.md	Every device the emulator models, its evidence in the firmware and the manuals, and what is stubbed
docs/reference.md	The full manual: every command and option, the drive format, the compare's tolerances, and the assumptions of each development stage

Related projects

This project is one of three that work together:

• MS43 Tuner: the Windows app and command-line tool: live logging, map editing, live tuning, bin compare and road performance tests.
• MS43X001 Custom: MS43X001 with the live-tuning overlay that MS43 Tuner talks to, plus pops & bangs and a downshift blip.

Contributing

Bug reports and pull requests are welcome; see CONTRIBUTING.md. Never attach a bin to an issue or a pull request: describe it (firmware, SHA-256) instead.

License

GPL-3.0-only (LICENSE). The emulator contains no ECU firmware. The C166 instruction set manual and the C167CR user's manual it was written from are Infineon's and are not included. MS43X001 is by the MS4X project; Siemens MS43 software belongs to its owners.