Electronic Power Steering Controller

DC Electronics in the UK sell a EPAS (Electronic Power Assisted Steering). The basic version comes with a potentiometer (knob) adjustment. You can also buy a ECU that is very expensive. We have designed a cheaper alternative. As well as selling this controller we have made all the information available for free for you to make your own.

The EPAS requires two signals to control its operation. Both of these are PWM signals. One of the signals turns the controller on and off. This is a 0hz for off and 100hz for on. The other signal controls the amount of assistance. 10hz gives full assistance and 500hz the minimum.


EPAS Steering controller.

It is common for people to state that the DC electronics controller does not make much difference from low to high settings. Unlike the DC electronics controller the TFE controller gives you full control over the amount of assistance based on vehicle speed or with manual pot control.

Price for TFE controller is $275 AUD. This price includes the harness and software.



Real time display of vehicle speed, assistance percentage. Speed input calibration based on meters per signal pulse. Calibrations can be saved and loaded from a file.

Automatic mode:
Assistance can to tuned based on vehicle speed.

Manual mode:
In manual mode either the internal pot or external can be selected.


Make your own controller

The following information is free for you to use and modify as you require.

Circuit design schematic   EPAScontroller.pdf
Wiring diagram   EPAS_Wiring.GIF
Source code for Atmel Atmega168   EPAScontrollerFirmware.zip
Compiled Hex file   EPAScontroller.hex
PC Software code (C++ Builder 2010) includes program exe EPAScontrollerPCsoftCode.zip
Proteus schematic/PCB design files   EPAScontrollerProteus.zip
PCB Gerber files   EPAScontrollerGerber.zip
If there is other information you require, then just ask.