Friday, August 19, 2011

Sorry it has been so long

Sometimes things come up, and I don't have time, other times things come up and I want to make time. This week was pretty exciting. It contained a few disappointments too, but overall, it was positive, and I feel the need to share.

Some of the tough stuff, to start with. I went to Minnesota to get my airplane. When I left it last fall, it was all signed off and ready to go. The prop needed torquing and a quick going over, and it was ready to fly. Things started out tough, and I kept wanting to quit, but people kept encouraging me, so I kept going. About 2:30 on Sunday, lined it up on the end of runway 10L, pushed the throttle forward, and it rolled and rolled and rolled. Finally at about 80kts, and most of the way down the runway, I gave up. The plane wouldn't rotate. It seemed to be running fine, but I couldn't get it off the ground. When I got back to the hangar, I found it wouldn't idle on the one mag. It shouldn't have taken that much runway, and it seemed to be down on power. Something to look into, but I needed to catch a plane at 4:30 if I was to get home for work on Monday, so I abandoned it for that trip. I'll give it another shot in a couple weeks.

I get some EE Times emails, and one this week had a new National Semiconductor 12bit A/D convertor that can do over 2G samples/second. Wow! talk about the perfect software defined radio (SDR) chip. That is amazing, and I am sure it will start appearing in some radios soon. Think about Nyquist theorem, it should allow hooking up to an antenna, and getting usable data up to almost 1GHz. No down convertors needed!
The app sheets National has on their page seem to reflect this also.

More good news on Hack-a-day, Heathkit is going to start building kits again! Their kits were top notch, and I certainly built my share of them. I still have a couple, and hope they maintain the quality. They are looking for ideas for kits to add. They are promising a wireless pool monitor as one of their first kits, and I hope it is good, since that is something I have considered building myself. Especially in the winter, going out and messing with the pool is a hassle.

Tonight, I went to MicroCenter, the closest place where I know I can get printer ink, and other PC accessories. I was able to get a Linux compatible USB WiFi device for my laptop. Asus makes it, I'll let you know if it works. I so much miss Linux at home. I have it at work but it is so crippled it is almost as bad as windows! While I was there, it appears they are setting up a little Maker Space with Make magazine, and various kits, including Arduino and various sensors and shields. The prices weren't bad either. Hack-a-day is saying Radio Shack is trying to be hobbyist friendly too.

We will just have to see what happens. Hopefully there will be some solid follow through, and Heathkit will be good, radio shack will be helpful, and the economy will pick up.

Sunday, July 24, 2011

Lots of Distractions

I've been messing with a few things, the kids had a cubmobile race, and my wife had plenty of things for me to mess with. Along the way, I've been only reading about stuff. This week, Hackaday had some talk about this Jerri person who is building a FPGA software defined radio. I've been reading hackaday for a couple years, and always find some really cool info.

It turns out this Jerri person is Jeri Ellsworth, another self taught engineer. Instantly I respect her, but after seeing her work, I am even more impressed. She publishes a vlog, and a blog about her hobby work, and some other stuff. I've only been reading about her a couple days, but I thing this is really good info.

She is up to part 6 of her vlog reporting about this, and will end up publishing on element14. Suddenly I know about element14. Well, I knew about it a while ago, but never really paid any attention it is, since I had no idea if they sold something, or what they did. I've been getting EE Times and Embeded Systems Design magazines for about 20 years, and they are getting thinner and thinner, probably a sign of the times.

I've always enjoyed Circuit Cellar Ink, and still have issue 1, and a bunch of older Byte magazines, where Steve got his start. The price is up to almost $40/year ($45 for print) for the magazine, and that is scarey, and sad. It eliminates a bunch of people from being able to afford it, or thinking really hard about the magazine. It has always been at the high end, with limited advertising, and great content, but now I think it went too far. We will see how long that lasts.

The other thing I saw, Garmin has an "affordable" transponder for ADS/B. Turns out it is a 1090ES transponder. Well, that is a non-starter for GA as far as I am concerned. The FAA wants everyone below 18000ft to be using UATs, not 1090es transponders. This transponder is still about $2500, and UAT's are
still priced less. I am guessing this is "affordable" in the business jet jargon.

I promise to get back to my original project, check back next week.


Monday, June 20, 2011

I quit, but I'm back

I almost gave up on the project. Financial times were getting tight, I was frustrated about all the other stuff that I needed to take care of. Some clown was able to get into my paypal account, and take all my ebay sales money, plus a little more. Paypal made things good, but it took a couple weeks to work out. A couple other things happened, and I was able to make the money deal work out.

My laptop had a flakey hard drive, so I bought a new one. 50GB for $500. Sure the 1TB drives aren't a lot more, but they are 3-1/2" ones. Internal laptop drives are a little more expensive. IT works better than before, plenty of space, but I still have to load all the software. I've gotten everything loaded, and the arduino talks to it fine. Tonight I installed Java, and waiting for eclipse to download.

I still have very little time, but I am making progress. I've built the protoboard. I modified it to be stackable with the bluetooth module, and am testing with an LM34, for the OAT sensor. Once I get the Eclipse installed, along with the amarino software fully configured, I should be good to go with the screen layout. I guess that is something I could have been working on all alone.

Keep the notes coming in. Love the feedback.

Wednesday, June 1, 2011

It works!

I finally got the itread studio stackable bluetooth card. It works right out of the box (or appears to, I haven't actually written code to make it do something). It connected right to the amarino app on the phone. I was a little nervous about plugging this into a mega arduino, since it doesn't have the same pinout as the basic arduino. Using the schematics for both the arduino and the shield, and dang, they line up. Being stackable, the pins are still usable (mostly).

I also ordered some blank prototype boards from itread studio. They are the mega sized ones, so I shouldn't loose anything. The board appears to have space to put one of the bluetooth boards, so I may be able to replace this shield with the prototype board. I should plan it out, and put things in eagle so that I can build a engine monitor shield. It only takes time.

I would like to get more folks coming to this site. I am looking for good ideas to get this promoted. It seems I am not spending enough time building to finish, so I don't feel strong about pushing things until I am done, in case I don't finish.

Feedback would be welcome.

Sunday, May 22, 2011

I am still here.

I just haven't done anything in a week. Lots of kids stuff, and work. I did order that other bluetooth card, and sold some more on eBay, so maybe I can get another Arduino. Maybe I should save up for a new laptop, my  wife wants a new desktop.

Maybe I am the only one in the world who doesn't respect some certain big time aviation mapping company in the world. I think their maps are cool, but their software stinks. I've been dealing a bit with that all week in my professional life, and it seems I sort of being ostracized. Weird, it is like the airplane manufacturer that owns the mapping company is pulling some serious strings. But, the CEO of our company is kind of pushing them.

Hopefully I get to keep my job. Then I can buy more computers.

Sunday, May 15, 2011

Amazing things happen in 24 Hours

My bluetooth card showed up a couple hours after I wrote the last post. Wow! that cars is smaller than I imagined!

So where to start. Well, the documentation leaves something to be desired. Seed has a Wiki page that has some pointers, including the pinouts of the card. It seems to be quite capable. But, so far I can't get it to work. I don't know if I need to connect more than power and Rx/Tx? It appears it needs to run on 3.3V, and my ArduinoMega has a 3.3V pin, so that seems right. Lots of grounds on the board, so that seems good. I connected reset, but this page made it seem like I didn't need to, so I disconnected it. Back in the day, We used to connect pins 6, 8, and 20 in the DB-25 connectors to get around hardware handshaking, so I connected RTS and CTS, but nothing.

I also had some issues with libraries and installing them. The Zip files come with a sub directory, so I'd install a new library in libraries/foo/foo/ well the apps wouldn't compile. I got pretty frustrated, but moving the libraries up to the proper place (IE libraries/foo) the code would compile.

How about this;, there is a schematic and everything! It is a little confusing, their schematic has a level converter (RS-232) but the pinout shows TTL level. Hmmm... 

I also found this card, for $19 I should buy it, since it'll get me prototyping area too. There seem to be many Arduino to Bluetooth solutions available.

I've got some other things to do, I'll get back to this.

I'll see when I  can get back to this.

Saturday, May 14, 2011

Google is Helping!

This week Google has their developer conference, and they announced the Android Open Accessory Development Kit (AODK). It is based on the Arduino board, and talked USB. Buying from Google is expensive, but hackaday has a user who figured out how to use  any old Arduino to do the same thing. I need to look into this some more, since I am cheap, and have lots of ideas for the Arduino Android connection.

Seed Studio still hasn't devlivered the bluetooth shield I ordered a couple weeks ago. It is giving this vendor a black eye in my view. I probably out to write to them before complaining too much.

Not much progress on this project in the last week. Mostly working on stuff around the house. Floor upstairs, end of school year kind of things.

Write if you have thoughts.

Monday, May 9, 2011


I've been thinking about the display. I briefly looked at the Nokia LCD shields for the Arduino, but have so far dismissed them. I've also looked at the larger monochrome displays available, and similar dismissed them.The Nokia displays, while color are too small (128x128 pixels and about 2.5" square), where the large ones are fine, they only are monochrome.

There is a bunch of information one can encode in a color display, everything from warnings, to dithering edges to allow more data on less screen. I am sure I could, if so motivated, put enough information on one small color display. Connecting multiple of these smaller displays up to a network from the main board is another option, maybe allowing 2-1/4" holes to display analog looking gauges. It would certainly be an option.

Using a larger monochome display could work, and for many years there was the popular VM-1000 display that was monochrome. Alerts could be encoded as blinking or changing presentation, including reverse video. The display can show analog and digital presentations, allowing quick checks for out of tolerance readings, and a longer view of specific readings.

Combining displays, making a comprehensive view will allow quick scans to determine more information. Combining all oil and temp into a single graph would allow noting any issues with the oiling system. A similar display could show CHT's and EGT's allowing quick viewing of current cooling status. The comprehensive display will allow showing more data in a larger color display.

Using direct connected displays would also have the disadvantage of requiring something to be farther from the engine. The display being close to the pilot would need to have all the sensor wires brought forward, where mounting the display and engine monitor near the engine would require the pilot to turn around to read the display. (We are talking a Cozy here, not a Cessna, but something similar to an Osprey II or non-traditional engine mounting would be covered).

I am planning on using an Android device for a display. The Android can receive the Arduino data over bluetooth, and possibly USB. Currently tablets are available for about $150 on up, or if you have an Android phone, it should work without any additional expense.The Android has a robust open development platform, and the tools are mostly open.

Using bluetooth allows the option of connecting to other devices, including full laptops, ipads, and other brand computers. I am not going to work on them, but all others to do it if they desire. This is an open project, read and learn along with me.

Tuesday, May 3, 2011

General Avionics Questions

Today the comment came up:

  Are there any pilots that, if you were designing and buying avionics for a Cozy panel from scratch..GPS/NAV/COM/GS/Intercom that would...price point for the GPS/NAV/COM/GS box could be in the $2-2.5k range

Well, I responded, and then I had some explaining to do. I went rambling on about Software Defined Radios (SDR), and I thought most people don't know what a software defined radio is. It is an amazing item, but so far they are kind of expensive (or not). The SDR is able to listen to multiple conversations at once. There are many ham radio operators that have SDRs on line. There is a WebSDR group, allowing multiple people to listen to radios all over the world. I said that right, one SDR can receive many conversations at once, allowing multiple people to listen to the same radio at the same time, on their own station! You can listen to frequency A I can listen to frequency B and someone else can listen to frequency C, each in their own mode (AM/FM/SSB etc). Also, with this software, you can "see" where the conversations are happening.

SDRs can transmit also. They are just as capable transmitters as receivers. They can operate in many modes, including TV (digital and analog). I think the first one was GnuRadio, and then TAPR got involved.  So far things are mostly aimed at ham radio operators, since like experimental airplane builders, they have more latitude within the rules.

Sounds complicated, right. Well, sometimes software is complicated, but people build fancy interfaces to make it simple. There will still end up being a lot of electronics in an SDR, but they are amazingly flexible. Depending on the design, some can do some amazing things.

Imagine flying along, and the GPS quits, (never happens right? check out, and look at the Grid Display Tool, click on the non-precision approach (NPA) button, all that red, hmm.. GPS isn't good enough to use for approaches), what do you do? Well, you have your SDR VOR receiver listen for a bunch of VORs, all at the same time. The receiver has a morse code decoder built in, and a database of VOR lat/lons. Just using triangulation, this sucker can determine where you are, with a reasonable degree of accuracy. Throw in some DME receiving, an ILS or two, and you should know where you are better than the GPS.

I envision some day, we will have devices we carry in our pockets that will be all SDR. So the smart phone that has become ubiquitous can do lots, but it has many radios, and they can be on a lot, burning batteries. How about the SDR having a smart mode, where the radio knows where you are, and uses the correct frequency in the one transceiver based on location.  Say you want to talk to someone across the room, why waste cell tower, use a different frequency, and talk directly to the person. Say you want to watch TV or listen to the baseball game on an AM radio, the SDR can do that. Need satellite radio, no problem.

As you can see, things are changing in the world of radio. No more random tuning and hoping, no more locking us in to old click click tuning, soon the radios will tune in to what we need.

Saturday, April 30, 2011

Frustration Part 1.

I'll call this part 1, since I'll have plenty of frustration. Something won't go as expected, and I'll have to do some extra work, or wait on something. I ordered the bluetooth shield from someone in the US thinking I'd get it quicker with lots of ready to go documentation. Turns out, they source it from China, and it takes the same couple weeks as if I ordered it from ebay. They do have docs on line, so that is pretty good.

Time is another factor. With work and family stuff, I just am not getting to work on this too much. I know I need to order the amplifier chips, some of the other discretes and maybe a proto board. I mostly want to have the full design done, so I don't waste time with some small orders, and filler parts that I don't need. I am sure it'll happen eventually, but I don't want to start off that way.

I'll have to pick up some thermocouples and maybe oil pressure/temp sensors and play with them. I was thinking putting 'em on my car would be a good test. At least it would give me a benchmark, and let me know if I am in the ball park with the software/GUI and all.

I am just kind of excited about getting some data from the arduino to the phone, then I can feel like I am moving forward.

Wednesday, April 27, 2011

First shot at the thermocouples

I sort of came up with the schematic. Eagle got a little creative with the symbol names, but I am not sending this out to have the board fabricated, so it probably isn't critical.

The upper clump is the CHT thermocouples, the lower clump is the EGT thermocouples. Each group with their own temperature compensating circuit. I didn't put any values on this. It is mostly an expanded version of the schematic in the Linear LT1014 data sheet. That datasheet has some interesting resistor values (IE 199K) I'll play with things a little bit, to see how accurate I get it with standard components. I suspect, it'll be good enough.

The datasheet is shooting for 10mV / degree C, I can use math to change to 9.82mV / degree C or even 10.28mV.

I've ordered the bluetooth shield, and expect it before the weekend. I am kicking myself, since I ordered from seed studio, and they  have prototype shields (cheap too!) that I didn't order one of those at the same time.

Again, any feedback is more than welcome.

Friday, April 22, 2011

What have I gotten myself into

Today was an interesting day. I started looking at the accessories I need to make this work. It looks like I will have to spend some money. The bluetooth shield will be about $60-70. I looked at the BlueSmirf and the bluetooth mate, both are more than the main board. That is what it costs to do stuff I guess.

It seems weird, because almost all phones have bluetooth capabilities, even the cheap ones, and they usually don't cost like that. I know Arduino shields are low production items, but wow! I was thinking maybe $20-30, I guess I can't guess well.

I've been looking at amplifiers for the project. I originally was considering the LTC1050, since that is what I was using before. Then thinking of multiplexing it, with some 4066's or something. Today I found the LT1014's, 4 in a package, and the datasheet shows cold compensating, so you can get 3 per package, and the are about $5 each, in a DIP package from Mouser. To do 8 inputs, it will take 3 packages, not bad.

There is also an Arduino proto shield, I found. That ought to be useful, allowing me to build the adapter on a good looking board, instead of by hand on a perf board.

I looked at the MAX6675 A/D converter. It would work, but they are really expensive, 8 would be about $100! I keep looking, and think the LT1014's are the right choice.

For schematics and such, I've used eaglecad in the past, and will probably use it for this. The free version limits your board size and number of components, but I think this will fit in the limits enough.

Another shield I found a few months ago is the autopilot. That will probably be my follow on project.  If this doesn't turn into a FADEC at least. I want to head into the FADEC direction, but will be very careful, and have overrides until I am sure it works (and even then if I design for override, I'll probably keep the design).

Wednesday, April 20, 2011

Testing the Aurdino

I actually got the board 2 days ago. Some home projects and family items have kept from it. I followed the instructions on the Getting Started Page. It worked right out of the box (envelope, whatever)! The first time I plugged the board in, I got the dreaded Blue Screen of Death windows is famous for. (long story, yes I am a Linux guy, but life throws curves at you all the time, dang WiFi port quit on my laptop, then the windows driver for the replacement USB WiFi port, was only 32 bit, but I have a 64bit processor, and the linux system didn't work. Anyway, now the hard drive is going bad, do I fix everything, or find a new laptop before something else breaks?). The Arduino folk are building this to work with whatever, so I can use windows, and be successful! After a reboot, and loading the drivers like instructed, I was successful at running the blink app. I also found the serial monitor, and was able to see the output from several other example programs.

The Arduino folks are really smart, and have some really good tools. Everything is automatic or almost. You change the code, and correct syntax is highlighted, incorrect is not. The uploader can be run using Control U, a pulldown menu, or from the shortcut button. I had to set my port and board:

  • Port: COM4
  • Board: ArduinoMega 1280

I need to at least come up with the block diagram of what hooks to what. Again, for analog inputs, I will have 4 J thermocouples, and 4  K thermocouples for the EGT and CHT's, oil pressure and temperature, fuel pressure and outside air temperature. For digital inputs, the RPM will need to be measured, probably on an interrupt. There is room for additional digital inputs, including landing gear position, flaps or spoiler position. Analog inputs for throttle, mixture and carb heat position. Outputs may include a speaker or input to the intercom, assorted LEDs, and finally using bluetooth, to the Android.

A consideration I have, the amplifiers needed for the thermocouples are somewhat expensive, like about $5 per chip. One chip per channel, meaning over $40 for amplifiers alone (or $60 if I used a 6 cylinder). That is more than I paid for the Arduino board. That is fine, but there is another way, using multiplexers. Something like a 4066 or another analog switch. I need to do that research.

I think the next thing I will do is start building the tester. It'll have a couple amplifiers for the thermocouples, then I'll have the connector for the other analog inputs, with some op-amp (lm324?) to allow scaling the inputs. Another digital input will be for the tachometer input (opto coupler?).

Sunday, April 17, 2011

Link Page

While I was building my airplane, I had a link page, a place where I  would always go and check stuff. If I was looking for something for the plane, I'd try ebay, needing info about a radio, one of the radio retail sites, or the manufacturer. It was tough sometimes, since links change all the time, but here goes. I may build another one later, or just keep editing this one.

Airplane Parts
  • - Wow,  need I say more, cheap ads, super deals.
  • - The old standby, not printed on yellow paper anymore, but same feeling.
  • ebay motors - Ebay, but the better place to start looking for airplane bits.

Arduino Links
  • The main page - software, schematics, and everything else.
  • Amarino - Android meets arduino, lots of hints and tricks.

Android Links

Book Stores (cause I don't do that one big book seller)
  • - since ebay bought 'em it isn't as fun, but still cheap.
  • A1 books - similar deals as, but alas, bankruptcy caught 'em.
  • Bookmooch - free books? You betcha! well, exchange 'em.
  • Bookins - more free books? how can borders stay in business (oh, never mind).

I've pretty much decided I don't have all the links I need. Should I do electronics retailers? Aircraft parts catalogs? you  tell me. Plenty of room in the comments part. Hey, if you think your link belongs here, I'd love to hear about it also.

Wednesday, April 13, 2011

People are Pendantic

Recently I participated in a debate around pitot heaters. Reading the FAR's (CFR 14, what used to be called FARs when I started flying (not that long ago)), there is nothing about having a heated pitot in little airplanes. Even though most manufactured airplanes have heated pitot tubes. Some people believe everyone must have one, no certifications (experimental or otherwise) can be granted without one.

(this gets a little technical, flying talk, there are hints at the end)

Now I am not advocating not having them, but I will say that if you stay out of moisture when it is cold, you should never have pitot icing trouble. There isn't any air flowing into a pitot tube, it wouldn't work if there was air flowing through it. It measures pressure, so the air gets packed into the tube, and the airspeed indicator reflects the pressure, and that is how it works.

The air can't make things colder than the air temprature, that is physics. Flying at high speed, the wind chill only counts as a feel, not as reality. If you  have a windchill factor of 40degrees below zero C, and the air is 5degrees C, the air can only cool metal to 5degrees C. Now if you are flying and the air temperature is above 0C, then there shouldn't be much freezing going on. Of course, the temperature may vary along the route, and a 3 degree lapse rate may allow you to go below zero, if there are any altitude deviations.

Having a heated pitot tube will allow you to know how fast you are going, even if the airplane picks up ice. Is knowing how fast you are going with a load of ice good news or bad? It may not matter, if you get too much ice. The FAA just issued a SAIB for icing, that seemed to show some common sense in a document. They caught some flak for it, since it was common sense, something  everyone should know. Probably they get tired of getting called out to muddy farm fields, to look at broken airplanes, and are wishing that problem would just go away.

So what does any of this have to do with building an engine monitor?

The engine monitor may want to know the temperature of the air going into the engine. Or at least around the engine to know the change in temperature (deltaT) that is happening. Are the CHTs higher today than yesterday, is it because it is warmer out today? It will be a baseline to know how well the instrument is performing.

I expect people will be different or smarter than me. I hope I can stir some thinking.

Watch those temps

Monday, April 11, 2011

What am I trying to do?

It occurred to me that I didn't really cover what I am trying to do. I am trying to monitor the engine on my airplane. I am trying to build a device that will allow me to monitor the engine parameters in real-time while flying. The device will have alarms and other such passive devices such that if I am busy flying, it will try to get my attention, before something really bad happens.

Airplane Engine???

What is unique about an airplane engine? Normally, for smaller aircraft, and airplane engine is an air cooled piston engine. There are two primary manufacturers, Lycoming and Continental. They have similar designations for their engines, a typical indicator will be something similar to:

The fist letter "O" stands for opposed. Some people call this a boxer engine, Subaru, and Porsche are typical manufactures of this layout of an engine. The manufacturers also use an "R" for radial. Radial engines are roundish, and you'll see them on WWII aircraft.

The next number is the displacement of the engine. 360 is for the number of cubic inches of displacement. Common other values are 320, 540 and 720. A Ford 302 is similar, with 302 cubic inches of displacement (or 5 liters).

The values after the the cubic inches define some accessories and other details about the internal parts of the engine.

My Engine

The engine on my airplane is an O-360A1D engine. It is a 4 cylinder air cooled carbureted engine. It produces about 180HP at 2700RPM. The propeller is attached to the crankshaft through an extension. The slow turning is ideal, and prevents the propeller tip speeds from going supersonic. (I could get into the math, but you can do it if you want. My propeller is 76" diameter, 3ft radius, and arcing at 45 RPSecond you can see pi * d is about 19ft, and 45 times that is 848 ft per second times 3600 and you end up about 578 miles per hour, at the tip).


I want to monitor the cylinder cooling. The baffling on the engine is designed to cool the cylinders, and the air must be efficiently be directed around them. Measuring the individual cylinder head temps (CHT) will help determine the quality of the baffling, and indicate the even flow around them.

The exhaust gas temperature (EGT) can help determine the correct mixture, and even burning of the fuel. As the airplane goes higher, the air is thinner, meaning the mixture must be adjusted to help maintain the proper air fuel mixture. If the temps go down, the extra fuel is coming out the exhaust, and the mixture should be leaned. Cars have mass airflow sensors to maintain good mixture, airplanes have a mixture lever.

The engine RPM will be monitored to be sure the proper speed is maintained, and the engine is running as expected.

Oil is the lifeblood of the engine.  Proper temperatures, and pressure will insure the oil is doing it's job. It has two purposes in this engine; provide lubrication and provide some cooling. There is an oil cooler on the engine, and I want to be sure it is operating properly, without too much or too little cooling.

Fuel pressure is something else to watch. There are two fuel pumps on the engine, mechanical and electric. I need to be sure the fuel can get from the tank to the engine as expected. The pumps will help that happen. The fuel pressure will indicate that is working, and if there are any issues.

Those are the main things that I will monitor. Other things will come up. This design is flexible enough that someone with a 6 cylinder engine could use the design.

Sunday, April 10, 2011

Getting Started

I decided to build an airplane about 15 years ago. A lot has changed since then. The idea of a glass panel, back then was almost unthinkable for any reasonable amount of money. Today, a glass panel is pretty common. There was one company building a complete graphical engine monitor, and a couple doing bits and pieces. Today there are dozens.

Why should I do this...

I have a different idea. I think the ones out there are too darn expensive. Sure the bill of materials they have chosen probably necessitates the price. Sunlight readable LCD displays are expensive, along with all the software and reliability that is needed in the box. Switches, cases and connectors are special for use in an aircraft.

Airplanes are different than cars. High speed and constant vibration are going to cause issues, it is hard to install them. Installation, and building are two different things. Installation issues are the same, almost, no matter what unit is purchased.

My idea is different. I like the idea of component equipment. Have a display box, a data access box, and maybe eventually have an air data computer. Using components, I can upgrade one component at a time, and not have to bother the whole system. If you have a integrated nave system (car or airplane) how many times have you said, I wish this worked like my phone (or had some other new feature).

Components are more expensive...

For stereos, you can buy a boombox or other integrated stereo for far less than component stereo equipment. That is reality. Components are pretty standard in home audio world. In the computer world, things are rapidly becoming standard, but you can't quite plug and play this and that. Communication standards are available, and there are plenty of standards to choose from.

My design is hopefully, going to allow me to upgrade parts that I feel need upgrading without destroying what I have working.

I've been working on this for a while...

About 5 years ago, I started prototyping something. I started with an OEM AT mega board and a prototype board. I had connectors for thermocouples, for CHT and EGT probes, and some other A/D converter connections for the oil pressure and temperature. I had a serial output, that I could connect to a laptop, or a Zaurus mobile internet device, and a GPS board that I started playing with. I got distracted with the GPS board, and never quite started messing more with the engine monitor.

During the last couple years, I knew enough about GPS by now to get a job working on RNP satellite monitoring. That was a good benefit, but now I want to go further and do real live avionics type work.

My idea...

The idea is to stick with the AT mega, but use a COTs board, an Arduino board. An Arduino Mega board has 16 A/D converters, and many digital IO pins. The analog inputs will be:
  1. 4 CHT probes
  2. 4 EGT probes
  3. Oil Temp
  4. Oil Pressure
  5. Fuel Pressure
  6. Fuel Level
  7. OAT
  8. Manifold Pressure
Digital inputs may include fuel flow, engine RPM, and various status switches (trip start, etc).

For a display, I was thinking of using one of my phones or mobile internet devices. They are inexpensive (I've already paid for 'em). They have touch screens, and pretty good graphics. If this whole thing works, I would like to get a tablet computer for this.

For communications from the Arduino to the display, I had considered using USB, since almost everything uses that, but then I found a project that allows the Arduino to talk bluetooth to an Android phone. The perfect place to start.

Where am I today???

I've ordered the Arduino Mega board, I've gone through my old notes about my project, and I've downloaded the Arduino software. I've read the hello world example (blinky), and tutorials 1-85 or so (not really, maybe 1-8). We will just have to see where things go, and how far I get.

How is all this going to work?

I am not really sure. I've never blogged before. I thought it a good way to get my thoughts out there, and allow someone to repeat my work, if it is mildly successful. If it a wretched failure, well, there may still be stuff to learn.

I have lots to do in my real life, this will only be a hobby. If I don't write anything for weeks, give me a nudge, I might be doing something useful, and unable to write. If I don't write for months, maybe the project will be dead.