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-   -   Displaying voltage, oil pressure, oil temp etc. (

bikemaniac 11-18-2011 02:31 AM

Displaying voltage, oil pressure, oil temp etc.

I stumbled over the MPGuino site and realized that I need to look closer into that topic. Actually I just want to install a plug and play ScanGauge system, however my car does not have an active OBD plug and no electronic fuel injection. It is an old fashioned diesel car with mechanical fuel injection. My main focus is not displaying fuel consumption (however, it would be nice), however the following classic gauges are of my interest:

1. Oil pressure
2. Oil temperature
3. Voltage
4. Amps
5. Outside temperature

The thing is, that all these gauges are perfectly available from manufacturers such as VDO. However, their diameter is too large and will not fit. Moreover I want to display many gauges and there just is not any space for that. Thats why I need a compact digital system.

So basically its all about handling sensors which change their resistance values (or voltages) and display these values on a small screen (with conversion factors).

For that purpose I want to install a basic lcd display module into the DIN Radio compartment of the car. The dimensions are approx. 175x50 mm.

Can anyone help in guiding me into the correct direction of that project?


chris917 12-30-2011 06:54 AM

I've actually wanted the same thing for years - so I built one. The first version used a PIC16F877A microcontroller and serial LCD module from, as well as a handful of temperature sensors (DS18B20) and a pressure sender meant for a prosport gauge. I designed a DIN slot adaptor in solidworks that would hold the gauge as well. Never ended up installing it though, got distracted rewriting all the code for a 32 bit microcontroller. I still have the 8-bit code if you're interested.


dcb 12-30-2011 08:27 AM

yah it is a pretty simple task for the code. I think arduino is a good fit for this, lots of examples of displaying values on an lcd and the microcontroller has several analog ports. The hardware interface is pretty simple too if taken one port at a time.

1. Oil pressure: might need aftermarket sensor and a tee, but divide it to a 5v peak signal.
2. Oil temperature: same as temp
3. Voltage: use voltage divider (can use internal resistor in processor as part of divider)
4. Amps: use shunt and op-amp, or use hall effect sensor.
5. Outside temperature: thermistor as part of voltage divider

Each of these will look like an analog signal to the arduino (basically an atmega) and the basic arduino comes with six analog ports.

init lcd and analog ports

read pressure on pressure analog port
update pressure on lcd
read oil temp on temp analog port
update temp on lcd

drmiller100 12-30-2011 12:28 PM

I would be REALLY interested in something like this.

I only want MPG, and for a Honda, and for OBD1 (like a 93 civic). I would want instantaneous and a resettable average.

Anyone interested in building one?

dcb 12-31-2011 06:39 PM

OpenGauge / MPGuino FE computer - Fuel Economy, Hypermiling, EcoModding News and Forum -

drmiller100 12-31-2011 08:49 PM

that is pretty cool!

how much donation is typical?

dcb 01-01-2012 12:20 AM

$55 shipped, but it is on hold till the current backlog clears. Though with you building cars and stuff, you might do well to build one from an arduino and learn a bit about microcontrollers, etc. See the version 1 thread and the wiki.

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