Digital Automotive Gauge - OBD

Digital Automotive Scan Gauge

View Automotive Values Electronically

Description

The Digital Automotive Gauge is an electronic scan gauge, which may be used to display various values(Battery Voltage, Engine Load, Coolant Temperature, Engine RPM, and more) from your automobile in real time. It can display two values at once, and has the following features:

Simple to connect. Merely plug the 16-pin OBDII connector into your car's diagnostic plug (usually below the steering wheel and easily accesible).
Easy to mount. The device uses a rugged rectangular aluminum enclosure, which can be mounted on the dash with velcro.
Easy to move. The device can be transferred between vehicles easily, by just unplugging the 16-pin OBD connector
Easy to use. Two buttons are used to cycle through the values displayed on the two lines of the display.
Low power. The device uses less than 1watt of power. When the vehicle is turned off, the device automatically powers itself off.
Rugged automotive electronics. The device is designed with rugged automotive-quality electronic parts.
Easy to read. The device incorporates a two-line high contrast lcd display, which includes a backlight for night-time use.
High compatibility. This device is compatible with all 2008 and newer vehicles (which use CAN-based OBDII).
Low price. Introductory price below $100.

The gauge utilizes your vehicles OBDII connector, and uses CAN communication to retrieve the requested data. This CAN standard is included in all model year 2008 (and newer) vehicles. So the gauge will work with all vehicles sold in the United States, which are 2008 or newer. It will also work with older vehicles which incorporate a CAN-based OBDII connector. If you are unsure that your pre-2008 vehicle is compatible, you can send me an email and I will verify compatibility. The Install / User Guide may be downloaded here.

Gauge Readings

The following automotive values are able to be displayed, in real time:

Intake Air Temperature
Engine Coolant Temperature
Engine Oil Temperature
Manifold Absolute Air Pressure
Mass Air Flow Rate
Throttle Position
Engine Load
Vehicle Speed
Engine RPM
Fuel Level
Battery Voltage

Any two gauge values may be displayed at a time. Pressing the left button cycles through the values displayed on the top line. Pressing the right button cycles through the values displayed on the bottom line. In addition, the gauge may be set to display a single value (by pressing both buttons at once). In this mode a value is displayed on the lower line, while a graphical representation (bargraph) of the value is displayed on the top line. The two modes are shown below.

The Gauge set to display two values (RPM and %Throttle) / The Gauge set to display one value with bargraph

Two additional customer requested values may be added to the gauge, for a small fee ($30). For instance, on a flex-fuel vehicle it may be useful to add the Alcohol Fuel Percentage value. The only requirement is that values to be added are standard PIDs, documented in the SAE J1979 standard.

* Keep in mind that not all vehicles will support all value types.

Development Kit

A development kit version of this device is also available. The kit contains a standard Digital Gauge, along with the full source code (C language) and schematics for the display. This will allow programmers to create their own CAN display functions, and tailor it to specific uses. The source code can be modified to display different parameters, or you can just keep the low-level drivers and completely re-write the current functions.

By removing the 4 rear screws, the circuit board slides easily out of the enclosure. See photo below.

There is a 10-pin ISP (In System Programming) header available for reprogramming the flash-based microcontroller.

To compile the C language software, you will need a compiler. The "uC/51 ANSI C Compiler for 8051 family" is a FREE compiler and is available here: http://www.wickenhaeuser.de/ I have created a project file for this compiler, it can be compiled and built successfully with no changes.

To download the output from the compiler (HEX file), an ISP device programmer is required. The "8051prog2 USB In-System Programmer" is a $69 programmer which can program the microcontroller, and is available here: http://www.mikroe.com/en/tools/8051prog2/ Alternatively, the "Presto USB In-Circuit Programmer" is a $150 programmer which will also work, and is available here: http://microcontrollershop.com/product_info.php?products_id=814

The Digital Gauge hardware was originally designed for in-vehicle applications, but may be used for monitoring any equipment which incorporates a CAN bus. The gauge can be powered from a voltage supply range of 10VDC to 30VDC, and has an average current draw of less than 50mA.