BMW E46 Cluster Interface Board

SimHub-BMW-E46-Cluster-Module

This repo contains all of the circuitry, code, and resources used to create a shield board for an Arduino Mega that could be used to communicate with a BWM E46 instrument cluster from a PC. The main application of this project was in using the cluster in conjunction with SimHub in order to show the values from the supported video games on the cluster's gauges.

All of the testing I performed was on an E46 cluster with the following ID number and firmware:

• Cluster Serial Number: 1031098105
• Cluster Hardware Number: 30 (Can retrieve this by running the on-board 'Test 1' on the cluster, in test 1.5)
• Cluster Software Number: 360 (Can retrieve this by running the on-board 'Test 1' on the cluster, in test 1.5)

See the following link for how to retreive this data: https://www.e46fanatics.com/threads/just-found-us-version-of-hidden-menu.239619/

Credits

There is no way I could have accomplished this project without many of the resources available to me:

• I never would have got off the ground if it weren't for this pinout diagram for the cluster: https://www.bmwgm5.com/E46_IKE_Connections.htm
• I borrowed several functions / hardware connections from Neuros-Projekte, as well as most all of the KBUS communication methods: https://neuros-projekte.de/simulator/bmw-e46-arduino-simhub/
• Most all of the CAN communication was from the extensive research done by the users on this bimmerforums forum: https://www.bimmerforums.com/forum/showthread.php?1887229-E46-Can-bus-project
• amstudio on YouTube for introducing me to using SimHub, and providing a solid foundation to design my custom protocol on top of: https://www.youtube.com/watch?v=L59NL9EuEdM&ab_channel=amstudio

Hardware Design

The circuit designed for this project was designed as a shield for an Arduino Mega microcontroller board. The purpose of this circuit was to take the signals from the Arduino Mega and use them to control the lights, gauges, and serial busses in the cluster. With this design, a user can supply 12V to the DC barrel jack input of the Arduino Mega in order to power the cluster, and then connect a USB-B cable from the computer running the video games to the Arduino to pass data between the computer and the Arduino.

Signals required to operate the cluster

In order to determine what signals I needed to drive the cluster, I searched for "E46 cluster pinout" and soon arrived at the following website which provided the pinout for the two connectors on the cluster: https://www.bmwgm5.com/E46_IKE_Connections.htm

With this, and the help of the people on the following forum, I was able to come up with the following table outlining what signals were required at each pin of the cluster:

BMW CAN Bus Forum: https://www.bimmerforums.com/forum/showthread.php?1887229-E46-Can-bus-project

X11175 Connector Pin Function / Signal Levels

X11176 Connector Pin Function / Signal Levels

Sub-Circuits used in cluster module

Basic Pull-Down Network

This circuit in essence acts like a switch: When the Arduino applies 5V to the input of the circuit, the MOSFET (the DMN67D8L-7 part) turn on, and pulls the cluster pin to ground. The current that flows in this case can be up to 30mA, so the part was selected so that it could handle at least this (the selected part can handle up to roughly 200 mA). If the Arduino applies 0V to the input of the circuit, the MOSFET turns off and the cluster pin is pulled back up to 12V.

This circuit is used to control the following pins:
X11175 Connector: 13, 17, 19, 20, 21, 22, 23, 24, 26
X11176 Connector: 4, 5, 6, 7, 12, 13

5V to 12V Level Shifter

This circuit acts very similar to the basic pull-down network: If the Arduino applies 5V on the input of the circuit, Q6 will turn on (connect the cluster pin to 12V), and Q4 will turn off. If the Arduino applies 0V on the input of the circuit, Q6 will turn off, and Q4 will turn on (connect the cluster pin to ground). The 10 Ohm resistor was added to limit the current going into the pin the circuit is connected to.

This circuit is used to control the following pins: X11175 Connector: 2, 7 X11176 Connector: 14

KBUS Level Shifter

When the Arduino applies 0V to this circuit, Q7 turns off, and pulls the gate of Q9 up to 5V. This turns on Q9, and thus applies 0V to cluster pin 14. When the Arduino applies 5V to this circuit, Q7 turns on, and pulls the gate of Q9 down to ground. This turns off Q9, and thus pulls cluster pin 14 up to 12V. This circuit is used to translate the 5V 'Serial' messages coming from the Arduino to 12V message signals that the cluster expects to see.

Ignition and Accessory Mode Circuits

When the Arduino applies 5V to this circuit, it turns on Q31, which then pulls the gate of Q32 down to ground. Q32 is a PMOS transistor, and thus this turns the FET 'ON' which then applies 12V to the cluster pin. When the Arduino applies 0V to this circuit, it turns Q31 off, which then pulls the gate of Q32 up to 12V. This turns the FET 'OFF' which then pulls the cluster pin down to ground.

This circuit was used to control the ignition and accessory mode cluster pins (X11175 pins 5 and 6 respectively)

SPI -> CAN Circuitry

This circuit is a direct copy of the circuit used on the MCP2515 SPI to CAN development boards, such as this one:

Fuel Level Circuit

This circuit is known more commonly as a 'shunt-regulator' (similar to the popular TL431 part you can find available online). This circuit makes more sense when you consider what the circuit on the input of the cluster looks like for X11175 Pins 11 and 15 (Tank1+ and Tank2+ respectively):

In this more simplified circuit, I represent the digital potentiometer as a normal potentiometer, and show what the input of the cluster looks like for the Tank+ pins. The idea is that as we change the value of the potentiometer, the gain of the circuit changes and causes the voltage at the Tank+ pin to change accordingly.

For example:
If the potentiometer is set to 0 ohms, the tank+ pin will be set to roughly 0.65V. To the cluster, this would look just the same as connecting a 50 Ohm resistor from the pin to ground. In the case that the potentiometer is set to 5kOhms, the voltage at the take+ pin will be set to roughly 2.7 Volts, which looks just the same as if a 397 Ohms resistor was connected from the pin to ground.

In this sense, the circuit acts as a variable resistor that we can set from the Arduino ranging between about 50 Ohms and 397 Ohms, which covers the normal operating range for this pin of a resistance value between 70 Ohms and 395 Ohms (see table above for tank+ pins). In theory, the same circuit could have also been used for the ambient temperature sensor, but I chose against this since it did not change system performance at all.

Other Circuits

There are a few circuits in the design containing connectors, DIP switches, and other such items that I do not cover here as they are more self-explanatory, but if you would like to know about any other part of of the schematic design, please let me know.

Arduino Code

For this project, I provided two main programs: E46_Cluster_Test, and main-simhub-code. The following section outlines these two programs, as well as the communication protocol that is common to both programs:

E46_Cluster_Test

This program was created in order to perform basic tests on the cluster. After uploading this code, you can send commands from the serial monitor to the Arduino, and then the Arduino will interact with the cluster in order to carry out the desired function. You must send every command with the following syntax:

In addition, make sure the Arduino Serial monitor is setup as shown below (most importantly, have the baud rate set to 9600, and the line ending set to 'Newline'):

See the section Valid Command / Argument Combos for both programs for a list of commands that you can send to the cluster, along with the effect each one has.

main-simhub-code

This program was created in order to interface with the cluster through the computer software SimHub, which allows you to send data from racing games to an Arduino. This program receieves data from SimHub, and using the same methods as the E46_Cluster_Test program, sets the cluster up to reflect the sent data. You have to upload this program to the Arduino before attempting to use the SimHub application, or else it will hijack the serial port and not let you program the Arduino until you close the application.

In order to make this application work with the hardware, you need to do the following:

1. Upload the main-simhub-code sketch to your Arduino
2. Open SimHub, and Navigate to the following menu: Arduino -> My Hardware
3. Confirm that there is a device connected in this menu
4. Under the Custom Protocol for this device, paste in the contents of the JavaScript_Protocol.txt file, and be sure to check the Use javascript box
5. Press OK at the bottom of the window

At this point, you should be able to launch games from the SimHub dashboard (ensure that you configure each game according to SimHub's instructions).

Valid Command / Argument Combos for both programs

The following is a list of valid commands and arguments that you can send to the instrument cluster from both applications. You can send these commands directly through the serial monitor for the E46_Cluster_Test program, or through a Custom Protocol in SimHub: