# Arduino-Based Instruments?

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#### Woodenwings

##### Well-Known Member
I am interested in using linear servos instead of linear actuators for both flaps and my fuselage mounted kickstand/divebrake.

It would be cool to have airspeed sensor input used to prevent the use of flaps at high speeds. Also have the divebrake self deploy before VNe.

Interior and exterior lighting is also easily controlled with an arduino.

I may not do the flap thing (because it is a critical system) but the interior lighting thing has already been programmed and tested.

Putting LED strips inside the fabric covered parts of the plane would look very fun for not much added weight. Totally stupid....but fun.

Another idea would be to have a small bright led stroe facing the pusher prop from two angles. Using prop rpm to make the prop appear to spin slowly in low light. Stop people from approaching from the rear and not seeing the danger.

When it comes to non critical systems the arduino could be very useful.

Water sensors in floats. Water sensor for fuel. Pressure differential sensor for fuel and oil filters. Outside temperature and cabin temperature.

You could also have a duepoint sensor made to warn of carb ice conditions.

I would love to replicate steam gauges with servos that can be custom made to look antique or simply have a unified style. The flight sim folks are already doing it. Just need to connect them to an i-levil instead of what they use.

The possibilities are endless.
The legitimate reasons for doing any of it as it relates to safety and prudence need to be paramount. Its very Easy to make a stupid thing very well!

Brain squirts/Rant complete!

#### Saville

##### Well-Known Member
It would be cool to have airspeed sensor input used to prevent the use of flaps at high speeds.

You could do that by feeding the digital airspeed (if you have it) to the Arduino and the Arduino could activate/deactivate a relay to the ground line of the flap motor. It could interrupt the power to the flap motor above a certain speed.

However your point about it being a critical. system is important, so the Arduino could simply light a red light
or otherwise alert you that you've deployed the flaps above Vfe.

Or, alternatively, keep the red light on unless and until you are below Vfe. The pilot can check the light before deployment.

However for the RV-8 at least you can extend the flaps 20 degrees at a higher speed than full flaps so you'd need a 2 tiered system. That would also get in the way of deploying the flaps at 20 degrees at the higher speed unless you also wired in a flap angle sensor and added Ard code for that.

#### ToddK

##### Well-Known Member
I really wish those guys would set up a wifi or bluetooth interface for android tablets. There are plenty of them available these days that are bright enough to be sunlight readable, probably as cheap as building the display, and would be full color, which is a very useful feature.

As far as I know he never could get the BNO055 working correctly. Its a real shame as for a VFR airplane its really not needed. If he would just omit it, do a big number ASI, ALT, GPS heading (possibly with a user adjustable correction factor below it) Time/timer it would be a great, fun, and handy build.

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#### huVVer

##### Member
I'm a new member of this forum. I have been actively been developing aircraft instrumentation for almost 20 years.

In the last year, I have introduced a family of open-source aircraft instruments based on custom hardware and free open-source software. More information is available at www.huvver.tech... check the links.

Most of my open-source hardware and software is flight tested and production hardened, being sold commercially by Vx Aviation and then MakerPlane for many years. Recently, I introduced the huVVer-AVI family of flight instruments that are in production at MakerPlane. These devices are robust (8-32 volt, with +/- 100 Volt protection) for aircraft use, and leverage my 40+ years of engineering and manufacturing expertise.

I also provide documentation under revision control to make things simple.

Right now, there are no hardware schematics, because with the supply chain disruptions I have to change the BOM to substitute parts on every production order (for the huVVer-AVI versions).

Sorry to hijack the thread, because I see a lot of innovation here, but I want to emphasize that not all Open Source stuff is unsupported.

Vern Little / Vx-Aviation / huVVer.tech

#### rv7charlie

##### Well-Known Member
Hi Vern,

Welcome aboard; good to see you here. Please open up a thread or two showing what you've been doing; I'll bet quite a few folks here will find your stuff interesting & useful.

(Vern's been active on another major homebuilt forum for years.)

Charlie

#### qchen98

I've found a Chinese supplier who makes differential pressure sensors for $4. I won't doubt the quality of them - those chips are used for medical purposes(respirators) routinely. Probably more reliable than most steam gauges. Those use I2C protocols and you can daisy chain them together. Therefore, you can easily implement a triple-redundancy system with them - in case one fails. Even the Garmin G1000 doesn't have three sensors. Similarly, you can put three cheap Chinese I2C accelerometers together to get a very-reliable gyroscope reading. At this point, an Arduino(especially the Chinese clone) is more like to fail than the sensors. However, you can also daisy-chain a couple of Arduino together with I2C and SPI lines - if one is not pinging the other one via SPI, the other one would immediately take over the I2C and SPI line(SPI lines is connected to the display). #### Aerowerx ##### Well-Known Member I've found a Chinese supplier who makes differential pressure sensors for$4.

I won't doubt the quality of them - those chips are used for medical purposes(respirators) routinely. Probably more reliable than most steam gauges.
Stay away from them! Yes, there are pressure sensors made for medical instruments, but are THOSE sensors used?

It is not worth the money you think you are saving. Many Chinese made parts do not meet the basic specs of the equivalent brand name parts. And some are outright counterfeit! Believe me, I have some experience with them.

It is OK to save some money by building your own instruments (besides being fun!), but you should make sure you are using quality parts. So bite the bullet and order from Digikey.com (I am in no way connected with them other than being a satisfied customer, and there are other parts houses that are equally reputable).

#### rv7charlie

##### Well-Known Member
Hey Aerowerx, I'm curious. Do you use any kind of tablet when you fly? Would you mind sharing with us which one?

#### Aerowerx

##### Well-Known Member
Hey Aerowerx, I'm curious. Do you use any kind of tablet when you fly? Would you mind sharing with us which one?
I am not flying currently. Wish I could afford to.

Several years ago I was interested in building so joined this forum, but realized it was a bad decision. I really didn't have the skills required. Besides, where would I park the thing?

I was also intrigued by tailless aircraft design.

I am using Arduino/Teensy/MEMS sensors on other projects. I had bought what I thought was a uBlox Neo-M8N GPS receiver. When I tried to use it for my current project I found that it didn't meet even the basic specs. Further investigation revealed that it was a Chinese counterfeit, so at 4x the price I bought one from Digikey that worked perfectly.

#### Aerowerx

##### Well-Known Member
Deleted double post. Don't know why it did that.

#### rv7charlie

##### Well-Known Member
Sorry you're not able to fly at present. But just as a heads-up for future reference, I think that you'll find that an extremely high percentage of pilots are using Foreflight for flight planning, and as either a primary or backup tool. And a lot of VFR pilots use it for keeping their VFR sectionals current, so they'll be legal on cross-country flights. And I'm pretty sure that a lot of the airlines are using, not Foreflight, but software with similar functionality to replace their paper charts. Guess what device is required for Foreflight, and for the airlines' software. Now, where would you think that device is made?

#### Saville

##### Well-Known Member
Sorry you're not able to fly at present. But just as a heads-up for future reference, I think that you'll find that an extremely high percentage of pilots are using Foreflight for flight planning, and as either a primary or backup tool. And a lot of VFR pilots use it for keeping their VFR sectionals current, so they'll be legal on cross-country flights. And I'm pretty sure that a lot of the airlines are using, not Foreflight, but software with similar functionality to replace their paper charts. Guess what device is required for Foreflight, and for the airlines' software. Now, where would you think that device is made?

Charlie,

I get the impression that Aerowerx is speaking about one particular quality level of device - not all devices from China. He's talking about a cheap one. I don't know if that cheap one is used in tablets.

At least that's my take on his writing

#### rv7charlie

##### Well-Known Member
Well, he extrapolated from a single experience with a single GPS puck to (apparently) any Chinese-mfgrd device. There's not really any relationship between the GPS puck and a differential pressure sensor, except the mfg location.

It's a pretty safe bet that there are dozens of Chinese semiconductors, chips, passive components, etc, flying in just about any IFR navigator you can find these days, in addition to the absolute fact that every ipad is made in China. Judgement made on a product that hasn't even been used by the 'judge', based purely on country of origin, when it's well known that other products from that same country are considered to be high enough quality to be used by the airlines is...what?

#### Aerowerx

##### Well-Known Member
Well, he extrapolated from a single experience with a single GPS puck to (apparently) any Chinese-mfgrd device. There's not really any relationship between the GPS puck and a differential pressure sensor, except the mfg location.

It's a pretty safe bet that there are dozens of Chinese semiconductors, chips, passive components, etc, flying in just about any IFR navigator you can find these days, in addition to the absolute fact that every ipad is made in China. Judgement made on a product that hasn't even been used by the 'judge', based purely on country of origin, when it's well known that other products from that same country are considered to be high enough quality to be used by the airlines is...what?
It is not based on just one device (the GPS). I gave that as an example of an outright counterfeit, that had an OEM label but certainly did not meet specs.

I have had problems with other components, besides seeing comments from other users. Yes, you may be able to get quality parts from China but IMHO you are taking a big risk. One comment I read was that you pay extra for the quality in Chinese parts. If you pay a bargain basement price, expect bargain basement quality.

As for ipads, from this website:
Yes, they are made (assembled) in China, using components sourced from multiple countries.
And I am sure that Apple pays the extra price to get quality work.

I suppose you could buy a bunch of components from China and test them to see if they meet your requirements, but in the long run you would probably be better off just paying extra for know quality from a reputable source.

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#### CAVU Mark

##### Well-Known Member
Quality is always suspect with China, look at the marketing plan from Harbor Freight. The low cost products don't last long and just to save a few bucks and support a totalitarian government is not a bargain in the long run.

#### BJC

##### Well-Known Member
Quality is always suspect with China, look at the marketing plan from Harbor Freight. The low cost products don't last long and just to save a few bucks and support a totalitarian government is not a bargain in the long run.
The marketing plan for HF, a privately owned company in the USA, is a product of consumer demand in the USA.

BJC

#### rv7charlie

##### Well-Known Member
Yep, and a rather large percentage of components (and complete products, like the i-stuff) 'made' and sold by USA companies are actually made in China. You can buy junk, and good stuff, made there, and you can buy junk, and good stuff, made in the USA (just not nearly as much of either one, because US companies have outsourced virtually all mfg to other countries). I fully understand (and share) the distaste for supporting an authoritarian regime, but that's a completely different issue from quality questions. We could talk about support for/opposition to States that are bad actors, & be forced to include issues like the US borrowing money from them, etc, but then we'd be talking something other than a/c building.

The empirical evidence is that it's quite possible to get quality stuff from China, so blanket statements that Chinese products are of poor quality and/or counterfeit seem to be motivated by...something else.

#### Rhino

##### Well-Known Member
Deleted double post. Don't know why it did that.
Because sometimes you click the "Post reply" button and absolutely nothing happens. So you assume you didn't click it correctly and click it again. Voila! Double posts! Unfortunately this forum doesn't allow you to delete posts.

#### dwalker

##### Well-Known Member
This is going to hurt some feelings, but...

A few years ago I toured several factories in China, specifically in Shenzhen, as we were making some decisions to have private label parts manufactured overseas. I could write a very, very long article about the perception vs reality of Chinese manufacturing, but here I will simply say that the Chinese factories are as good or better than anything we can do in the US. I toured US facilities and was never impressed by how clean the facilities, machines, and employees were, how dedicated the actual employees- the ones handling the materials and watching machines run- were, and how hard it was to deal with industry reps who were exceedingly arrogant where they really needed to be humble.
On the contrast, every Chinese factory I toured- and mind you these were not scheduled tours, I just showed up, announced myself and in all but one case my contact was very happy to give me a tour. The factories were cleaner than anything I have seen in America outside or DARPA level facilities. Every employee was in uniform, were very clean, and attentive to thier work. The machines themselves looked like they were brand new, and their QC department were diligent about random testing and lot to lot control. I will say that QC is a "get what you pay for" thing in China, if you pay for best level QC you will get that if you pay for bargain level QC that is exactly what you are going to get, and I have a neat story about that. Back on topic- the engineering staff, management, etc. were all very humble and gave a sense of wanting to understand what was wanted rather than trying to tell us "how it would be". In the end the only reason we did not proceed was the initial cost to set up the various lines of products was a little higher than I felt the market would handle, and I did not want to get stuck with a bunch of inventory instead of cash. There is a very good reason that all the best cellphones and computers in the world are not made in the US.

The US is CAPABLE of making the best products in the world and indeed, we prove we can on a regular basis, but far too many US made products are no longer the best in the world. We should fix that.

Incidentally I have that very differential pressure sensor that I used for a drone project and will use another one with arduino Mega to provide a backup airspeed indication in case of main flight instrument failure. It worked perfectly on the drone despite many, many crashes, rain (not supposed to get them wet but meh.. it happens) and Utah moon dust.

#### Cardmarc

##### Well-Known Member
My brother and I have built an Arduino based hydraulic pressure sensor/display prototype, with a few added options to boot. It is a supplemental instrument as no hydraulic pressure gauge was supplied originally. But it's for an RG, so.........I'd like to know the pressures. 3D printed faceplate. Also accomodates 4 new CB's.