# Arduino altimeter & airspeed indicator

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#### cluttonfred

##### Well-Known Member
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#### Aviator168

##### Well-Known Member
Fact is, all you need is 2 chips and a display to do this.

#### FritzW

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Log Member
Not intended for aircraft, but food for thought
I wouldn't hesitate to fly with something like that.

#### Pops

##### Well-Known Member
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A lot can be done with just a differential pressure sensor. I have been using a Motorola MPX-5100 DP for several projects. 0 to 100 kpa, .5 Volt offset, full span 4.0 volts. Want a AOA indicator, no problem, cascade two LM-391's for 20 LED bar indicator.

I used this pressure sensor for a low vacuum alarm for many years after I had a vacuum failure a few miles from an ILS approch down to minimums on a stormy day. The audio alarm was tied to the audio panel. Red case in the pictures. Also picture of the Motorola Pressure Sensor.
Also used the same sensor to switch the Hobbs meter on at 50 mph on the take-off roll for a airplane giving rides by time. Lots of uses and simple is good.

Dan

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#### cluttonfred

##### Well-Known Member
HBA Supporter
The more I troll through sites like Arduino - Home and Adafruit Industries, Unique & fun DIY electronics and kits and https://www.sparkfun.com/, the more I think, "Hey, I think I could do this." How about a combined ALT/VSI/ASI sized to fit in a standard 3 1/8 in instrument hole using just LEDs? Calculator-style, four-digit, seven-segment numeric displays for ALT and ASI, with a circle or bar of LEDs to give an at-a-glance analog indication of speed and a small cluster of LEDs to serve as the VSI: X means holding steady, up arrow for climb, slow blinking up arrow for faster climb, fast blinking up arrow for fastest climb, opposite for descent. You could even use varying colors--blue for climb, red for descent, green for holding stead, for example.

#### FritzW

##### Well-Known Member
Log Member
You might look through all the FPV stuff also.

#### Aviator168

##### Well-Known Member
How about a combined ALT/VSI/ASI sized to fit in a standard 3 1/8 in instrument hole using just LEDs?
Not so fast. Altimeter requires barometer valve and temperature. So you are going to input these values or detect them.

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#### Blue Chips

##### Well-Known Member
Not so fast. Altimeter requires barometer valve and temperature. So you are going to input these valves or detect them.
Dangit, just when my mind was on a roll

#### Aviator168

##### Well-Known Member
Valves!!!!!!!!Thought they went out with the Ark.:gig:
That's what happens when you use a touch screen keyboard. Boy I miss my BlackBerry.

#### Topaz

##### Super Moderator
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As much as dedicated individual instruments appeals to the electrical tinkerer, I think a more-profitable future would use the Arduino to gather information from a variety of sensors and pass the information to an app on a commercial tablet like an iPad or Nexus, which does the integration and display of the data. The tablet already contains a compass and multi-axis accelerometers, so between that and the Arduino polling analog sensors for ram pressure, static pressure, and OAT (and doing some pre-processing), you'd have all the makings of a full panel. Put in a couple of small "steam gauge" backups for airspeed and altimeter, and you'd be a long way towards a full digital flight deck, at a fraction of the cost.

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#### spduffee

##### Well-Known Member
Funny, I was just looking at these, too. I just redid my instrument panel in my Phantom ultralight to get more knee room. In my new panel, either because I am a minimalist, or because I f'd it up, I don't have room for the 3-1/8" altimeter and my 3-1/8" airspeed indicator. I don't think I need the altimeter in an ultralight anyway, but just in case I started looking at DIY altimeters. This one popped up. It is for an R/C, but probably good enough. I will post anything I find, too.

A compact, Arduino altimeter for RC Planes

#### Aviator168

##### Well-Known Member
That's a lot easier Topaz. The Arduino + Bluetooth is about $20. You than add the various different sensors and each one would be no more than a few$. The difficult one is the attitude indicator. There are a lot of "fake" mem gyro out there and most of them are just accelerometers.

spduffee. I looked at their implementation. It is good for RCs and probably good enough for UL if you are just flying around you local area. I like the integrated pressure and temperature sensor; but for serious uses, I would choose a different implementation. One that takes in the barometer into account.

#### cluttonfred

##### Well-Known Member
HBA Supporter
I don't think the two concepts are exclusive. The same Arduino processor and sensors used to drive dedicated instruments could also be used to send data to a tablet. What I have in mind is a three-instrument cluster--one for flight data (ALT/VSI/ASI), one for engine data (might just buy that one) and one for navigation (basic GPS) backed up by wind in my hair (flight data), noise in ears (engine data), a whiskey compass and a paper chart (navigation). On the GPS, I love the simplicity of John Bendict's Gipsi, an audio only GPS, and might like to combine that concept with a basic visual interface to show course and speed and altitude and guidance to preprogrammed waypoints or the nearest airfield much like John has done with his Gipsi Apps for Android. I don't know why, for some reason that three-hole panel idea just appeals to me. ;-)

#### Aviator168

Adding a display would not cost much more. A 7" TFT display with driver board is around $30. #### Topaz ##### Super Moderator Staff member Log Member Adding a display would not cost much more. A 7" TFT display with driver board is around$30.
Yeah, but why write the entire UI yourself? Plus a commercial tablet already has a touch-screen, and the API to access it. Why reinvent the wheel?

Unless that's specifically something you want to do, as its own challenge. In which case, carry on.

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