Once I get my Netduino+, I’ll be going through the simple stuff… one tutorial at a time. Eventually, I will get to the projects I really want to tackle. In that vein…

Question – I want to measure the angle of an object relative to the Earth. The Netduino+ and sensors will be on the object in question. I haven’t found a solution that meets all the requirements perfectly. I’m hoping someone has a better idea.

Details
• Object will be somewhere between 1 and 20 feet above a smooth floor.
• The angle relative to the Earth will be at most +/- 10 degrees
• I need the best resolution I can get… certainly less than 1 degree. 0.1 degrees would be great!
• I will need height also, but that can be separate sensors.

What I’ve Considered – I’ve ordered them to my best candidate based on my understanding of their limitations.

1. Using two of the ultrasonic sensors (http://www.sparkfun.com/products/9491) and measuring their relative height above the floor. Con: There resolution is 1 cm, so I’d need to have the two sensors over 18 feet apart to get my desired 0.1 degree resolution. I’d like to keep their distance apart less than 5 feet. Con: Expense… I’ll need about 20 of them… $900 Ouch!

2. Using two of the infrared sensors (http://www.sparkfun.com/products/242). Pro: Resolution is good enough. Con: Distance above the floor is too limited.

3. Using a gyro (http://www.sparkfun.com/products/9059). Con: It measures angular velocity and I’m under the impression that between factors like drift and the integration, I can not rely on it giving me repeatable results.

4. Using a two axis accelerometer (http://www.sparkfun.com/products/844) and calculating angle using a little Trig knowing gravity = 1.0. Con: Unfortunately the object may be accelerating up, down, forward and backward and I can’t see a way of removing those extra acceleration vectors.

Have you considered measuring magnetic field?

You know... I had a mental block... I was thinking liquid filled compass, 2D, in the horizontal plane.

But, you're right... From a high school physics standpoint, I recall... they are just lines of force and in 3D.

THANKS! That's the out-of-the-box thinking I was hoping for!

I'll dig into it tonight.

I am sorry, but...are you meaning the angle with the Y-axis, being perpendicular to the floor?
If so, why not a simple potentiometer (maybe a precision one), then read the resistance with some (simple) circuit?
Cheers

I appreciate your response... and keeping me honest!

I neglected to mention... the object is flying and I'm needing an accurate determination of its pitch angle (AOA)... hopefully in the 0.1 degree range.

Thanks

Well, I was bored. Here's an alternative ugly way to do this without using Split and Parse. Probably faster though.

Mati,

Have you or anyone else bench marked these two versions? The reason I ask... I'm new and awaiting my N+ and have too much time on my hand waiting. I read that the .NET on Netduino is interpreted and not JIT compiled like larger machines. However, I would assume all the .NET code would be precompiled. If so, I would think the Split/Parse methods would have an advantage over rolling our own substitutes. But, I'd be curious which assumption is correct.

Thanks!

I've been reading though this section a little and have read several messages about compiling...

BUT

In my reading through topics on the Internet, I found somewhere (I can't put my hands on the article now) that the code on Netduino is ONLY interpreted. There is no compiling to CLR, nor is there any JIT compiling on the CPU. It seemed to indicate that one's C# code is actually in the assembly. I took it as gospel and moved on, because it explained to me why the 48MHz/32bit Netduino is still slower than a 16Mhz/8bit Arduino.

So...
1) is the C# compiled to CLR on the desktop into the assembly?
2) is there a JIT compiler so code isn't "interpreted" every time its RE-run?

Note... I'm not complaining... obviously since I still picked to use the Netduino. Just curious... it won't change my mind either way.

I guess its another case of... "you can't always believe what you read on the Internet". Thanks Chris.

Microsoft continues to drive the core .NET MF platform forward, and the community is pitching in with both enhancements and bug fixes.

The Netduino roadmap is driven by the Secret Labs design team and feedback from the Netduino community. As we roll out new boards and accessories over the next 14 months, you'll instantly recognize the Netduino DNA as well as the community feedback that has been incorporated into their designs.

Chris

I too, being new, am trying to get the lay of the land... Where is it most appropriate to request something added in the .NET area? Last night I was running great guns (with my background of desktop .NET) and ran over a few pot holes and finally hit a wall.

I've seen some forums have the ability to set up voting... Is it desirable and possible for an Admin to create a "pinned" thread that allows forum members to add topics and let all forum members vote? This way… Microsoft, Secret Lab and developers with the interest and ability to add functionality can see what the level of interest for a given functionality. For instance… from just my last night’s work, I would want to request…

• string.Format()
• StringBuilder (that I see is coming in 4.2)
• Reflection being extended – I was ecstatic to see that it was there at all (I didn’t expect to find it). Using the Type.GetMethods() I was going great until I found no support for ParameterInfo and GetParameters.

All you need is a cast:

   int NumberOfSteps=(int)(Degrees/_CurrentResolution);

If you're an anal-retentive Aerospace Engineer (like me ) you might want to allow for the rounding instead of truncation and use one or the other of these...

    int NumberOfSteps = (int)(System.Math.Round(Degrees / _CurrentResolution));
    int NumberOfSteps = (int)(Degrees / _CurrentResolution + 0.5);

I agree with Mario, just use a simple pendulum constrained to only swinging in one plane (like the pendulum on a grandfather clock). The pendulum would swing from a simple potentiometer, and like he says there are simple ways to very accurately measure resistance. If you're worried about vibrations you could make it small and encase it in a box filled with nonconducting oil to dampen the vibrations. The viscosity of the oil would dictate how much damping you get.

Auger in!

Well... unfortunately, a pendulum although simple, won't work in my case. Think of this as being a low-flying airplane...

• It will be accelerating faster and slower - thus the pendulum's inertia will give a false reading and drive the plane into the ground or stall it.
• It will have some speed say (30 knots) – thus the pendulum’s air resistance will give a false reading and drive the plane into the ground.
• Every gram counts – Weights at the end of a pendulum, oil bath, etc… and the plane will never get off the ground.

Although complex computationally, if it works as I've been reading the magnetometer sounds like a good bet so far. I’ve got to get one and see. It has the benefits of (1) no inertia, (2) no air resistance and (3) light weight. Just got to see how it works in the real world.

I've got my Netduino Plus over this weekend... and I feel like I've worn it out!

Question
Is it possible to install the application over the network connection (instead of the USB)? I see that the .NET Micro Framework Deployment Tool has TCP/IP under the Device dropdown, but my device won't show up.

My real world case... the Netduino Plus would be connected on the other end of the Internet (say... at my bungalow in Tahiti or my ski chalet in Aspen “work with me here!”) And I know this might shock you… but I’ve been writing code for close to forty years and I still don’t write perfect code! I want to be able to upgrade the code remotely. Is it possible?

Hum, if the object is flying, the AOA has nothing...

FOR MY VERY SPECIFIC SITUATION - Everything I have stated is completely accurate... including AOA and it being “possible” to calculate it using the Earth’s gravity or magnetic fields (thanks JonnyBoats) as a relative datum.

And even though BernardG’s comments were derogatory in nature, I will try to use them constructively. I’m quite secure with my aerodynamic understanding, but my electronics knowledge is limited.

Can a potentiometer be configured such that by moving through only 10 degrees, the resulting input into the Netduino’s analog port uses its full 10bits without too much “noise” or resorting to a mechanical gear and be “fairly” linear? Would anyone be willing to suggest a circuit that might accomplish this?

Thanks!

Warning: Software type over his head with hardware

I have a friend that has a product that uses an FTDI chip set http://www.ftdichip....rivers/D2XX.htm. If I understand it/(him) correctly... it exposes two USB ports. 1 is a "Host" port (which I gather works like a PC's USB port). His device uses this port for something else. The second port is only a "slave?/client?" port (which I gather is like a jump drive).

He planned on using this second port to connect to a MiniPC so his product could be managed over the Internet via a web interface (that I would write). The FTDI chip set provides an excellent set of libraries for everything under the Sun... except for a Netduino. I see on the link above that they even provide drivers for other architectures like Windows CE 4.2 – 6.0 for ARM, MIP SII, MIP SIV, SH4.

I proposed to him that the Netduino might be a great fit (low power, no heavy OS, no disk, no fan… etc…). Of his shopping list of requirements the only one I couldn’t satisfy immediately was actually interfacing to the product through this second FTDI port. Is this even possible to connect to our MicroUSB port on a Netduino+? If so, how would I go about interfacing through it?

Thanks for your help!

Ran across this and remembered your request. A little pricy… but… http://www.sparkfun.com/products/10221

Stefan,

The more I read, learn, bookmark and… then… note who the teacher is… your avatar seems to come to mind the most. Thank you for sharing your expertise (and learning curve) here, all over the forum and on your personal web site.

I’m a software type with a real fuzzy picture of the hardware world. I currently have a little science project I want to create. I have scoped it out so far, such that I need…

• (4) PWM Outputs to control servos
• (15) Analog inputs to receive various sensory input (if it’s significant, I’m currently looking at a mix of IR Optical Detectors and Ultrasonic Range Finders)
• (~8) Digital outputs to light various LED’s for status and/or warning indicators.

From my simplistic concept of Multiplexing… it allows me to time slice between far more inputs or outputs than I have on the Netduino. In your example above, you have both inputs and outputs. But before I go and make an ass of myself for assuming something… does you example work for analog inputs?

If I understand correctly, could I move the purple wire from Port 12 of the Netduino… to Port 0? And then in the software read from this analog input instead?

Thanks your your help.

Thank you for your response...

I guess I need to learn how to wire something up like this...Serial/Analog Mux/Demux - 74HC4052 ...
... or better yet... 16 Channel Multiplexer


... it turns out they even have a wiring example with an Arduino for us hardware challenged individuals

<***OFF TOPIC***>
Assuming you're a programmer, imagine a world where's just one language to create your applications. That language has no owner than the universe, immutable since the beginning of the time, also will have no upgrades, nor evolution. You'll be granted it keep the same forever.
There are few rules, very well described, together with few tools. You know, few tools, but *good* tools. You may create everything with these tools.
There's no fuzzy depiction of this world: it's a well-ruled world called physics.
Welcome in the hardware world!

EDIT: I forgot to mention that IT HAS NO BUGS AT ALL!

I am an EE, but I love programming as well. I began over 30 years ago with software, and I must confess that I STILL HAVE A FUZZY PICTURE OF THE SOFTWARE WORLD!
</***OFF TOPIC***>

Inquisitor, both Stefan and ItsDan gave you good tips.
Your idea to use a CD4067 (16-1 mpx) is good as well.
Cheers.

Hi Mario,
I enjoyed your “Off Topic” … I think I detected a little sarcasm… because we all know Microsoft coding is bug free!
I guess I’m your double ganger with 30 years in the software world. … And… with a strong dose in Physics/Engineering. If I could have hooked up my computer to the real world, sensing and moving things in the price range this Netduino does, 30 years ago, I’m sure my life would have way different!

In my simple view of EE, I see… I just “tell” the CD4067 which sensor I want data, and then read the data on the single analog input. I just treat it like a big switch. I can deal with that!
I really liked Stafan and ItsDan idea as dealing with a com port is second nature to me… and again it would be my hardware limitations that shy me away from it. I don’t see how to get 15 of these little $1.13 sensors into a serial output… OR… having to pay a lot more for some equivalent sensor that does it for me and then get 15 of them.

CableGuy, Mario, I'll second on the wiki tutorial. Pardon my ignorance… my curiosity has gotten hold of me... from my 10,000 foot view I see this is a "digital potentiometer". Could either of you hi-light a typical real world use for this? You see… I am a mechanical, real-world kind of guy and I love the idea of interacting with the physical world through a Netduino and to/from C# code! I intuitively “get” a person turning a pot (or reading some other kind of sensor) and getting a value to use in my C# code. Since this digital potentiometer task warrants some large factory to create these, I understand it must be useful. Unfortunately, I’m missing that real-world use case. Thanks!

Hi

I am a beginner ....i am able to run a servo motor with netduino plus....Now i am thinking of running 4 servo motors with 2 netduino plus ..... Can anyone suggest me the steps .....


Thanks in advance

I’ll take a crack at it. There are four ports to control servos, so you don’t really have to use two Netduinos unless you just want to. Here someone has a single Netduino set up with four (pins 5,6, 9 and 10). It is a little difficult seeing where the wires go from the video, but if you’ve already successfully got one working, you should be fine. Also, note the Netduino can’t supply the servos enough power if they’re under any kind of load. (Warning: It could screw up your Netduino) Here another avid user has found a board to control eight with one Netduino. Hopefully, Stefan will reply… he’ll know how to power them from a separate power supply to keep your Netduino healthy if the little board doesn’t do it already.

I’ve done several searches of the forum and must not be using the right words. How do you all make these drawings of circuits? (Great example) Do you have some special CAD package? Where do you get these images of chips, breadboards, resistors and… of course… the Netduino such that they are scaled the same to fit the bread boards?

Thank! I've tried it out... and its great!

Here is my first project using the Netduino. It’s pretty simple by most of your all’s hardware and software projects here, but I’m really a “gear-head” at heart and interacting with the real world is key for me. If I could have done this 30 years ago (for this cheaply) I’d be a totally different person now. I envy you young people just starting out… you don’t know how sweet you have it thanks to the Netduino!

I've been noticing on this and other forums that many people are doing their own blogs. At my day job, we have been converting our product (and all us developers) over to a web-based product. Since I’m on a learning binge at work and at home with the Netduino, I thought a little more self abuse was in order. So I got a GoDaddy account and am learning how to use WordPress to offer up my first blog. Point being… I would really appreciate some constructive criticism on just about anything… spelling, grammar, colors, software and/or hardware.

www.messingwithreality.com/spinr-up/

Right now, the supplied code in the article is for prototyping. I’ve finished putting the code into a driver and have added shaft position features. I’m currently busy writing up the follow-on article and documentation for the class and members. I’m trying to figure out how to add a normal page that looks like Microsoft’s documentation.

Sorry to dig up an old post, but your project interests me also, and I was wondering if you've made any progress? I’m working on a similar problem, but I’m not as concerned about the display, but instead the actual gathering of the data. I think wiring into the existing tachometer sensor would be great, but I’m not sure how accurate it is on older cars. I also want crank position information so I can do engine timing related events. Anyway, I’ve just added this topic in case it might help with some of your plans... http://forums.netdui...ino-tachometer/

Hi Chris,

I'll raise a bug report. Unfortunately since our network is switched I don't think I'll be able to capture the N+ packets - my PC doesn't see them.

Les

Although your corporation might frown on it (some will)...
At my day job (an extremely large, security conscious corporation) we run on a gigabit switch network, some of us developers who need to use Wire Shark occasionally will also have a dumb, gigabit hub in our office… plugging in network, Netduino and your PC should allow you to “see” what’s going on between your N+ and the (anti-social ) company switch.

Below is a complete copy of my typical Daily Digest for one of the sub forums. You'll note there is a topic link after “Topic: Network Resetting Issue” and after that is a QUOTE. It turns out that quote has nothing to do with the topic link above it and it has no link of its own. And since I hang on every word said on this forum ( no sarcasm – you all are my morning ritual with coffee) I often… really want to find this thread. Sometimes I can find it using a search but other times, I get way too many hits. It doesn’t happen all the time… out of the four daily digests from last night, three had this problem and one did not.

Also, while you’re at it… it would be real nice if the link actually went to the last added message, instead of the start of the thread. I’ve seen this feature on several other forums.

Thanks for your help.

Inquisitor,

This your daily new topics digest!

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Forum: Netduino Plus
=====================================

-------------------------------------------
Topic: Network Resetting Issue (lesmondo -- Yesterday, 01:16 AM)
http://forums.netduino.com/index.php?/topic/2351-network-resetting-issue/
...........................................


------------ QUOTE ----------
(Our company was forced to develop such a service because this "secure 
access to devices behind firewalls/NATs" problem popped up in several 
customer projects.)


-----------------------------



I have briefly looked at yaler and I intend to look into it further. 
It looks pretty cool. However I am kinda leaning towards wanting the 
PC as the go between message router rather than going directly to 
the netduino.  I want to be able to cache, transform and restrict 
data flowing to my netduino devices.  The middleman PC gives me that
capability.


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