Here is where the hard stuff starts. The ADXL202E comes with nothing - it's going to come as a lonely IC in a anti-static box. No microcontroller, no PC board, nothing.

Now you'll have to round up all of the stuff you'll need to build the rest. If you want to use the Microchip application note as a starting point you'll need most of the parts shown in the schematic (PIC16F84A, crystal, voltage regulator, etc.) less the LCD. In place of the LCD you'll need some circuitry for the RS232 interface to your computer. The PIC they used doesn't have a hardware UART so I'm digging through my stuff looking for some serial bit banging code for the PIC. Between the app note code and the software UART you'll have all the code that's needed.

Will I need some way to feed the code into the controller? Do I have to buy a programer? Thanks for all of your help Ken.

Yes, you'll need a programmer. Fortunately the PIC16F84A is a very popular part in the hobbyist commununity and there are several low-cost programmer kits out there. You will also need the code assembler from Microchip called MPASM. They give it away on their web site.

dang you guys are good.... !

Xterrian, if you are going to go "glass cockpit" then perhaps this will work for you. Might blow your budget though!
Crossbow Gyro AI

Yeah, that's basicaly what I'm building. No heading info though, except for my GPS. I guess I could add that in to my program. Wow, one program accessing three serial port devices, that's just asking for trouble.

What do you think of this Ken? Do you think I can put together something similar for less than $100. That's all they want for it, and it seems to meet all my requirements.

Kayak, I just noticed that if you go to the second page of the pdf file linked to above, there is a picture of the Crossbow software running. Coincidence? I think not.

I prowled around the xbow site some more and it looks like they have a model for auto use. It also looks like you can download the software for free but I didn't try.
Anyway, I'm interested in what you are doing. At one point I was going to mount an old vacuum gyro driven AI that had been decertified for flying. Not much panel space for a 3 inch gauge though. They are pretty chunky.

Another link for you of somebody doing inertial guidance using the chip you are looking at using. You could browse his code etc. IGS

That's the evaluation board that Analog Devices makes to get engineers familiar with the part before they start their own designs. If you're only building one it's nice because you don't need a PIC programmer and you don't need to learn PIC assembly language. It's probably a faster path to your goal and hard to beat for $99. It could be all you need but you need to know some of its limitations.

Unlike the PIC16F84A in the app note circuit, the PIC16C63 has no non-volatile data memory. This means that the calibration values and offsets for "level" will have to be stored in the host PC rather than on the eval board. Probably no big deal.

The other limitation is that it uses the old version of the ADXL202 which is less accurate that the "E" part. The old part may be just fine for an inclinometer.

Damn Electroken, I wish I could give you another 5 rating. You are one hell of a resource for the Xterra community. Your encyclopedic knowledge of elctronics is priceless.

Well, I've gotten my tilt sensor samples from Fredericks. They look so cool, and the circuits to use them look so simple. An oscillator to give it some AC then an anolog to digital converter to give me PWM and then into the computer as hexidecimal value. No worries about it knowing which way is up. Fredericks even sells a board for it that puts out PWM for $100. I don't need perfect accuracy, so I believe I might be able to do something cheaper. Electroken, can you recommend some basic electronics books for building oscillator circuits? I really want, "The Art of Electronics" by Horowitz and Hill, but it's way too expensive. Know where I can get a used copy cheap? Sorry Ian, I want to support authors, but for a hobby, I can't pay $70 for a book. I already spend over a thousand dollars a year on medical textbooks.

Give me some idea of the frequency, duty cycle and amplitude you're after. There are many options.

I have the book you mentioned. You can't have mine.

I ordered a used copy for $25. I'm looking at running about 1KHz. The test circuit says 25 Hz to 20 KHz. Not sure about the duty cycle or amplitude. I picked 1 KHz out of my butt so I'm open to suggestion. My total lack of electronics knowledge makes it easy for me to believe it will be easy to do this. Maybe after I get my copy of, "The Art of Electronics" I'll realize how hard it really is.

Just so those that are interestd still know I'm working on it. I've included this link to a guy that built one for his personal radio telescope.
I'm still working on digesting, "The Art of Electronics", but I can only spend so much time in the bathroom.

Interesting link. $100 for only one axis.
How sensitive is your device going to be to acceleration? Dip a wheel in a gully and your reading could swing off the chart unless you damp/avg it somehow.

ok i just wanted to throw a post in here and say.

Ken, you are the man... i only understood about half of what you typed, and i find that damn impressive

Just to let you know Kayak, I still plan on building my own. It's just nice to see what others have done. Since I've never even seen an inclinometer in person, other than the Gyro actuated ones in small aircraft, it's good to get the nitty gritty on all of the options. I could probably build an anolog one for $25. I just want to integrate the output into my virtual dashboard. I'm still looking for a vga capable LCD to replace my real instrument cluster. I need something 15 inches wide by 5.5 inches tall. Multiple LCDs are ok. Please don't send me links to video input LCDs, VGA only please. I will nickel and dime it together until it works like I want it and looks stock. I just painted and mounted a touchpad next to my steering column and the cordless mouse is in the back seat for the kids. I have both of them working together at the same time. I just don't want to post too many pictures until I'm happy with things.

Very cool. When I talked to you at GOX I never thought you'd try to go through with the virtual dashboard. A lot of work, but I'm sure it will be worth it in the end. I'm looking forward to seeing pics. I just bought a new computer and am thinking of trying the indash computer thing with the old one if I can fiberglass some sort of mini case. Good luck!
John

Here's a crappy photoshop version that gives an idea of what I'm trying to do. The actual screen would be able to be customized for GPS, etc... No DVD to the dash screen for those that were worried.

xterrian, you are a sick puppy.

But i like it

Xterrian, why not rename your Xterra "KITT" and program in some AI so it will interact with you and make wisecracks as you drive.

When I was working on voice control of the computer I did have it saying some funny things back. "Oh great master of Visual Basic, I have started Mapsource as you ordered". The cabin is too noisy for current voice control technology though.

i can see it now...

"hello Randal"

"hello HAL"

"what are you doing"

"driving Odessa canyon"

"i can't let you do that"

this could get ugly

Hey Ken,what do you think about this cicuit for my electrolytic sensors?

Edited to add:
I ordered samples of the LCD and ADC from Maxim. Can you help me decide which PIC I need. There are too many choices when I put in PIC16C54C with Microchip.com