Digital Engine/Race Computer Board

Author, Designer and Project Maintainer: Stephen Manley -
Like to see more of this software? Send me an email or check out my other cool projects.


The objective of this project is to design a high speed digital engine tachometer. This requires the design and development of a hardware and software solution to monitor the status of an engine in real time. In addition, information relating to the overall health and systems of the vehicle can be displayed.

I'm currently working on getting the software ported to run on a gameboy circuit board with some modifications for the f-v converter. This depends on the specs I can find on the chip's DMA capabilities. This will allow a cheap implemention on the hardware side. For output, I'm working on connecting the gameboy's serial out or interfacing a 8256A. This will allow the display of the tach on some more sophisticated hardware, for example a PalmPilot or a notebook computer. I am also attempting to get it to run on a 486/100 single board computer. As the single board computer runs Linux, a minimal amount of interfacing would be required to make it work on a notebook computer or PC (although I don't know why you'd want to).

If anyone has specifications for OBD-II on a Honda Civic (1998 Coupe), and would like to see a portable software implementation written, please let me know and I will gladly do so! Finding good information on OBD-II is very difficult for an "open" standard.

My ultimate goal of all this work is to develop a preformance engine monitoring and race computer. Something along the lines of a computer interfaced to OBD-II and connected to an accellerometer and voltage measurement system, with an active matrix display. Future efforts will probably revolve around single board computers running linux, or possibly beheaded notebooks if I can get a good deal on a pentium class cpu. Check out Surplus Direct/Egghead.

If you would like to purchace one of these units, send me an email. I may concider getting some PCB's done and making a nice C&C machined case if there is some demand. Price would be in the $50-100 USD range for a digital tach, accellerometer, voltage and temp measurements with race computer functions (quarter mile timer, average speed, HP/RPM caluclations, etc). If this interests you drop me a line! I need 5-10 people to pay for the initial PCB prototyping. If you're interested in working on this stuff, send me a line too! :)

Current Features

Planned Features

Screenshots & Construction Photos

Board Top

Board Bottom (Yes it took awhile)

Tachometer in Operation

Another shot in Operation

Embedded Computer Design

The board has the following components as is. You probably need the schematic and the board layout to get anywhere.

Interface board

Either transistor or optical to generate ADC compatible voltage levels. See appendix for various schematics. These are basically frequency to voltage converters. This adapts the input to the LM2917 chip or 555 system. The design is flexible. See interfacing specifications for compatible voltage ranges for ADC conversion. (Under development)

2 x SPST Normally Open Switches & Switch Debouncer (Inverter)

Primarily used for debugging. User interaction occurs through a sophisticated serial interface which has the option of providing a interface mode such that other graphical client software can be run to provide a graphical, rendered set of controls.

4 LEDs - 2 Red, 2 Green

Used to indicate board activity, program flow, and alarm conditions.

Main Computer Board

X86 Compatible CPU, Memory and Bus arhitecture Any CPU which supports DMA, and has a C compiler and a 8 bit bus can probably be used.

8256A IO/Controller Serial and Parallel IO Ports

Required to output data to user and/or read switches. This is the primary means of interaction with the user.

0820 - Generic High Speed ADC chip (1Msamples/sec)

Converts voltage into a suitable digital signal for software processing.

EEPROM Expandibility

This allows for quick reprogramming of the board so that options can be changed by the client if they so desire and have access to the proper equipment.

Single Board Computer Design

I'm working on a solution that can work on a PC104 spec single board computer, either running linux or with a custom EEPROM. I'll keep updates here.

Operating and Programming

The device turns on automatically when power is supplied to the unit, through a power toggle switch. Once voltages are allowed to stabilize the unit will prompt you with a test, configuration and calibration, and active mode option menu. It is trivial to adapt this to send a string to a client such as a palmpilot for offboard processing and logging (the embedded design I have here is limited; A single board computer is a much better choice).

Download and Lisencing

This program is released under the terms of the GNU Public Liscence. Do what you will with it. If you are interested in it closed-source, email me and we can work something out. Please contact me if you are / are interested in working on this project further.

Grab the source code & makefiles. Code is written under a linux 2.x derivative and will probably compile best under such. This includes all the interface code, embedded code, etc that I have written to date.

Last Edited: 09/21/99
Created: 09/21/99
Maintained By: Stephen Manley -