Lotus Instrument Cluster Reverse Engineering

Initial release for FW 5.05 and FW 0.08


By using the information on this page you can render your device inoperable, damage your ECU, it might even explode or whatnot .. !
It is your own responsibility if use this information and
I take no liability for your actions !


This site focuses on how to access the instrument cluster via CAN bus via the built in (firmware release dependend) functions as well as the hardware/software layout of the device in order to write own software for it. This site only deals with the instrument cluster made by PI Shurlok, it does not descibe the original Stack made instrument.


To enable the RTC (Real Time Clock) functionality on the MY09 model device. Hardware is present, but firmware is not supporting the RTC.
This can either be fixed with an offical firmware upgrade that supports the MY09 hardware (if such exists), or by writing a custom firmware.
For that reversing the API used to upgrade firmware was nessecary. A lot of other stuff has been discovered next to that.

Supported Devices:

Functionality has currently been tested with the following devices:

MY09 - Lotus P/N: A121N6001F (kph) - Firmware V0.08
MY11 - Lotus P/N/: A121N007F (mph) - Firmware V5.05

Hardware PCB layout is different however a compatible CPU and similiar/same peripherials are used.
Firmware versions differ in functionalty (e.g. no clock on 0.08, however the needed hardware is present !)

KPH vs. MPH:

Except the gauge background scale there seems to be only a difference in software, flashing a mph software in a kph device and vice versa should be no problem. For V5.05 the information if its kph/mph is stored in the device's EEPROM so its even the same firmware thats used.
This could be true for the V0.08 firmware as well however the right EEPROM flag has not been discovered yet.