Digital gauge cluster for old car?

[Fredd0]

I recently bought an old Volvo 240 and want to add several gauges. Some are hard to find and there is also not too much room to mount without giving up some radio space. I am sure this type of thing has been beat to death at some point, but what I am thinking is a project to build a display that can be mounted in a small panel space about 3"X3" that will allow me to see a variety of parameters: oil pressure, oil temperature, outside ambient temperature, battery voltage, water temperature, transmission temperature, and maybe tach, ammeter. Scope would include finding, picking sendors and sensors and interfacing these inputs to a board with display output. Must be reasonably ruggedized for car app. Tach signal is already available, but unused in harnass. I really want to see all the data at once rather than scrolling through the data. Maybe just start with bars, but make sure to have the power to drive fancier display later. Each gauge could be handled seperately too, but not sure of pros and cons to big brain versus multiple discrete components.

Ideas are a bit vague now, but I could be satified with led bar graphs, not sure I need digits. Background is EE (power), but am interested in building knowledge base/experience with stamp, or pic, or something along those lines with idea of other projects. I started life with an electronics degree so I have built a few things, but it has been awhile. Not overly concerned with controller price (within reason) since it will be onesy type thing and I would like to have the computing power and I/O flexibility from the getgo. This is my first post hear so if this sounds crazy forgive me, I can always dream. Mainly looking for recommends for the brain, compiler, tools. Point me in a good direction work work too.

 

[mister_e]

a standard 4x16 maybe 4X20 character LCD could work and fit. If you have more time or want a better look, use a GLCD.

It's just display... a single brain would be enough, Microchip PIC or else microcontroller will do the job really well. Just feed all your signal to the PIC (with respect to the maximum input level), have a menu button (or more) and a LCD. Not much to make an happy bunny!

 

[Fredd0]

a standard 4x16 maybe 4X20 character LCD could work and fit. If you have more time or want a better look, use a GLCD.

It's just display... a single brain would be enough, Microchip PIC or else microcontroller will do the job really well. Just feed all your signal to the PIC (with respect to the maximum input level), have a menu button (or more) and a LCD. Not much to make an happy bunny!

Thanks.

Any particular pin count, compiler, tools, or protoboard flavors I should be steering towards?

 

[phalanx]

If you are familiar with C, there are 2 very good options from Microchip.

Both the PIC18F and dsPIC series would provide ample I/O and there is a free student version of Microchip's C compiler for them (C18 for PIC18F, C30 for dsPIC). Both series of controllers have DIP versions up to 40 pins that you can prototype with on a breadboard. If you need more pins, there are surface mount versions with up to 100.

For development tools you will use MPLAB which is Microchip's free IDE. For a programmer there is no better option then an ICD2. Whether you get the original one ($150), a clone like the one made by Olimex ($99-usb/RS232 or $50ish/RS232 only), or make a home brew one (~$10), you will be very hard pressed to find a better PIC programmer for the money (never mind the fact that it is a debugger as well).

 

[mister_e]

i will also opt for the 18F even if i think that most 16F will do the job really well.

Pin count? well it depen of how many sensor you want to monitor. Usually a Character LCD need at least 6 I/O in 4 bit mode. could a 18 pins be enough?

it's up to you to decide. some popular PICs
PIC16F876a
PIC16F877a
PIC18F452
PIC18F2520

Now you may use a compiler or use the free assembler. It's up to you again to decide. If your budget permit i'll suggest to buy a compiler. C, Basic or else don't really matter. Just pick the one who fit to your need and your budget. Learning assembler is also a must.. not a waste of time.

I have ICD-2 but rarely use it. It's a great programmer and debugger so far. Melabs do also a nice programmer (only) called EPIC. I don't have it but i hear great comment on this one since awhile.

Personnally i use BK 844a from BK precision to program my PICs. I use Melabs PICBASIC PRO or Hi-Tech C compilers.

 

[Fredd0]

Thanks, with more brainstorming

Thanks for the valuable input. I had seen the ICD2 and was thinking that it looked like a good unit and was probably going to be my choice. Didn't know the clones were out there. Anyway my dream got bigger, now I am thinking of the following:

Needs:
Voltmeter
Engine Oil Temp
Engine Oil Pressure
Engine Coolant Temp

Wants:
Ammeter
Tach
Speedo
Odo/trip
Fuel level
Fuel eco
Tranny Temp
Tranny Pressure
Ambient Outside temp
Ambient Inside temp
Air/Fuel Mixture

Discrete I/O stuff, idiot lights, fancier intermittent wipers, climate control, seat heat control (switches now), remote door locks (power door locks without remote now), "all windows power up/down from driver seat one touch" (generic power windows now), emission/ignition data


I believe based on reading my aftermarket manual that the temps and pressure senders are resistances that vary over a range in a typical current driven analog gauge type circuit. I am thinking I would just use the senders without gauges with scaling current to voltage opamp circuits to drive the adc. Same likely for fuel level. Maybe ambients and airfuel too. Not sure on those.

The voltmeter in would just be a scaling opamp circuit to an adc.

I think the ammeter function would rely on a extremely small accurate resistor providing voltage to a scaling opamp circuit to an adc input.

The tach, speedo, and odo would be counter functions with some math.

fuel economy would be a calc of some sort based on axle pulses/tach/fuel level/vacuum?

climate control and i/o pretty straightfoward.

Anything sound goofed up here? Do the op amp centric circuits makes sense or is there something else canned out there for this stuff? Missing anything? Can all this fit in a pic?

Sounds like I should just buy a modern car with a digital dash... nah.. that wouldn't be any fun and cost a lot more.

 

[Nigel Goodwin]

I think the ammeter function would rely on a extremely small accurate resistor providing voltage to a scaling opamp circuit to an adc input.

Obviously voltage loss is a major concern with an ammeter, but the magazine EPE (then called Practical Electronics) did a project years ago (when the LM3914/5 first came out) for a number of car instruments. For the ammeter they used what I've always thought was a very clever solution - they utilised the chassis strap from the battery, used an opamp to amplify the voltage drop across it, and got a nice ammeter reading with no extra voltage drop at all.

 

[bryan1]

Eh Freddo,
Ya might want to check out siliconchips electronics projects for performance cars book. I'm not sure of the price but under $20 rings a bell. Most of the projects can be bought as a kit but each project has a very good insightto how it works so with a bit of thinking and tweaking you could make them yourself.

Cheers Bryan

 

[Techno]

I don't have any advice other than this site to give you ideas on what your shooting for.
I bought it for my boat but haven't used it yet. Its the most complete single gauge for an engine I could find on the web. This company also has an extreme gauge even better but price is always important. Price complexity in building are the same thing.
https://www.grtavionics.com/turbopropEIS.htm