Asi

[Kerbo]

Here are some renderings of the circuit deck I designed.

The schematic and PCB were done with the free version of Eagle CAD and rendered using POVRay and Eagle3D.

The circuit is built on my breadboard and spinning a stepper with some quick diagnostic firmware so I am about ready to etch the PCB. Once the PCB is populated I will be tackling the full firmware.

The bottom view.


The top view. Note that not all parts I have used are modeled in 3D so they are not populated.
For example, at bottom center should be a USB connector and the large pads on the lower left are for a floppy style power connector.

[Kerbo]

I took my first flight with the ASI this weekend! I don't have a video of it in action yet but will soon. It is so cool to watch the ASI I built react to FSX.

The values on the gauge are not linear so I had to do some googling and dust off long unused math skills to do linear interpolation. I use eight known positions on the gauge and interpolate the other values.

The firmware that controls the gauge is pretty well complete but the software that gives values to the firmware is still rough. I used a simple C# program that pulls the IAS from FSX via FSUIPC, does some math to map to the required stepper position, then sends that value to the gauge firmware. This program needs a lot of polishing.

I will eventually be posting the circuit and software designs on my blog for anyone that is interested.

[Kerbo]

A short video of my test program exercising the ASI.

http://www.youtube.com/watch?v=Hgv5Uy-xzuE

[No Longer Active]

Hi Wriley,

Can i just ask how you learnt how to make all this? because i really want to make my own gages but i just havent a clue where to start? Where should we all start if we'd like to make a simple gauge like this?

Cheers buddy!

Alex

[Trevor Hale]

Hey Alex. Get Mike Powell's First book. Thats a great start, and its worth every penny.

Trev

[Kerbo]

Hi Wriley,

Can i just ask how you learnt how to make all this? because i really want to make my own gages but i just havent a clue where to start? Where should we all start if we'd like to make a simple gauge like this?

Cheers buddy!

Alex

Hi Alex,
That is an excellent question. I guess I learned how to do this by tinkering for about twenty-five years.

I think anyone with a little bit of mechanical ability can construct the gauge itself. I followed the design ideas in Mike Powell's book and made this gauge with very simple tools. At a minimum I would recommend having a drill press, a bench vise, hand files, calipers, and a hacksaw, along with the usual assortment of pliers, screwdrivers, etc. With these and some patience you should be able to build a simple gauge.

The next step would be constructing some sort of electronics that talks to a computer. Mike provides everything you need for one way to build this in his book. I prefer Atmel AVR (Mike uses Microchip PIC) microcontrollers and have some experience using them so I designed my own gauge circuit. When the design is complete I plan to make my schematics, firmware and PC software available as open source. The PC software will be more of a guide rather than a plug and play solution since it will most likely be tailored to my particular cockpit. If you have no electronics background you could use any number of off-the-shelf stepper or servo control boards such as those offered by OpenCockpits or Phidgets.

After you have the mechanical gauge and some electronics to make it move you need some software on your computer that makes the connection between your flight simulator program and the gauge. I have just enough programming skills to be dangerous so I am writing my own in Visual C#. You can download an express version of Visual C# for free from Microsoft here. I am getting the data needed to drive my gauges from FSUIPC so I started with the C# example provided with the FSUIPC SDK. If you don't want to tackle programming then you would need to use something off-the-shelf, such as SIOC for OpenCockpit's hardware.

As you can see there is a lot of opportunity for DIY but you can also mix and match with commercial pieces. If you don't know where to start I would recommend getting Mike's book, visiting your local hardware store for some materials and start building something. Start simple like I did with an easy gauge like an ASI or gyrocompass and go from there. This is one of the most helpful, friendly forums I have seen so you can count on plenty of help!

[Jackpilot]

Hi William

Glad I could (slightly) contribute...Looks really great!
Cheers
Jack

[No Longer Active]

Hey, cheers for the advice wriley!

Mikes book seems a good bet, there is a sample chapter of how to make a gyro compass using the stepper motor on his website, so may start making the compass! Shouldnt be nothing too hard i hope!

I'll update you shortly!

All the best!

Alex

[Kerbo]

I had a run of PCBs made for a USB stepper driver that can handle two stepper motors, 2 encoders, 1 switch and 2 optical interrupters (or switches). There are still a few parts needed that I don't have in stock. I can hardly wait to complete this ASI and fly with it.

[WJH308]

Looking good! You might want to consider buying a small lathe, like a TAIG or Sherline to help with the tricky concentric parts.