Author Topic: Moteino Variometer for RC Sailplanes  (Read 2774 times)

cgetman02

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Moteino Variometer for RC Sailplanes
« on: February 11, 2015, 01:05:56 AM »
I'm interested in creating a Variometer for my RC sailplane using the Moteino platform.  Seems like it would be the perfect device for creating a vario to sense altitude changes while flying.

When I first ran across this device today I seem to remember someone had posted that they had created an RC vario using the Moteino but now I can't find the post mentioning it.  I'd like to contact the person about their design.

Anyone else that is interested in sharing information about creating an RC sailplane variometer, I'm all ears!  What version of Moteino would seem to lend itself to my project.  I'm in the US so the radio module would be the US version.  Standard Moteino or Mega?  Extra memory capacity?

Thanks, Curt ;D

TomWS

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Re: Moteino Variometer for RC Sailplanes
« Reply #1 on: February 11, 2015, 07:49:40 AM »
Sounds like a fun project!

I wouldn't think you'd need a Mega for this, a standard Moteino should have all the processing power and memory you'd need. 
What is your weight budget? 
Are you building just one or several?  (you can optimize weight and cost by building your own PCB) 
How long does it need to run on a battery?
Do you need wireless programming or would having a 4-5 pin connector to attach debug cable be possible?

Just some questions that come to mind. 
Of personal interest to me, for a 'variometer', would you measure differential pressure?
And what effect are you measuring (speed, yaw, acceleration)?
How many samples per second would you need to have?
And what resolution (PSI/bit)?

Tom

cgetman02

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Re: Moteino Variometer for RC Sailplanes
« Reply #2 on: February 11, 2015, 07:54:51 PM »
Tom,  Thanks for the reply!  Not sure about some of your questions but I'll do some research.  Here is a thread on RCgroups that describes a similar vario to what I want to come up with.  It might be interesting to some of you.

http://www.rcgroups.com/forums/showthread.php?t=1749208

After finding the Moteino yesterday it seemed like a very useful candidate for this type of vario.

Curt

TomWS

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Re: Moteino Variometer for RC Sailplanes
« Reply #3 on: February 11, 2015, 08:27:54 PM »
Tom,  Thanks for the reply!  Not sure about some of your questions but I'll do some research.  Here is a thread on RCgroups that describes a similar vario to what I want to come up with.  It might be interesting to some of you.

http://www.rcgroups.com/forums/showthread.php?t=1749208

After finding the Moteino yesterday it seemed like a very useful candidate for this type of vario.

Curt
Wow, I wasn't aware of such a sensor!  I think the modules referenced at that site are gross overkill for the Moteino since they are designed for 5V arduino systems.  Technically, all you need, besides the Moteino module, is an MS5611 chip and two resistors! 

The code in the referenced site probably wouldn't need much change - I'm sure you'll be able to find help on this forum if you need.  The tricky part is mounting the MS5611 and the resistors.  I did find some searching on "MS5611 breakout", ex: http://www.csgshop.com/product.php?id_product=24

If you need help with the code, let us know...

UPDATE: I looked at the code and I think that the only REQUIRED change would be the #define led 13 would need to change to: #define led 9

Tom
PS: I think you should also add an accelerometer/gyro chip too    8)



« Last Edit: February 11, 2015, 09:00:13 PM by TomWS »

TomWS

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Re: Moteino Variometer for RC Sailplanes
« Reply #4 on: February 11, 2015, 08:49:27 PM »
I have a question re the location of the MS5611 in your plane.  Would it matter if its mounted on a 'shield' that simply plugs into a Moteino card or does it need to be mounted in a 'special' place that the Moteino/shield wouldn't fit?  The Moteino fits into a lot of small places... DAMHIKT. 

Seriously this would be a trivial board to design and fab.  I'd even follow up on my glib suggestion of adding a accel/gyro chip, the shield could have footprints for both and populate as needed...

Tom

cgetman02

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Re: Moteino Variometer for RC Sailplanes
« Reply #5 on: February 11, 2015, 11:56:34 PM »
Tom,  Thanks again for your input.  I have received a handful of these boards that I can send you a couple to experiment with if you would like.  BMP180 is similar to the MS5611 a little less $.

http://www.ebay.com/itm/200915895472?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

They are trying to kill me with overtime at work right now and don't have a lot of time to fiddle with my project.

I think a shield type installation should work.  Let me know if you are interested in a couple of the BMP180 boards to experiment with and I'll put a couple in the mail to you.  I'm just a hobbyist and don't have a lot of experience with programming.  I have been playing with the arduino formats trying to keep my old grey matter supple!

Thanks again for all your help and encouragement.  I'm anxiously awaiting more information and help with my project.  The programming end of the project gets deep fast for a person with little to no programming experience.

Curt

TomWS

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Re: Moteino Variometer for RC Sailplanes
« Reply #6 on: February 12, 2015, 07:46:52 AM »
Tom,  Thanks again for your input.  I have received a handful of these boards that I can send you a couple to experiment with if you would like.  BMP180 is similar to the MS5611 a little less $.

http://www.ebay.com/itm/200915895472?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

They are trying to kill me with overtime at work right now and don't have a lot of time to fiddle with my project.

I think a shield type installation should work.  Let me know if you are interested in a couple of the BMP180 boards to experiment with and I'll put a couple in the mail to you.  I'm just a hobbyist and don't have a lot of experience with programming.  I have been playing with the arduino formats trying to keep my old grey matter supple!

Thanks again for all your help and encouragement.  I'm anxiously awaiting more information and help with my project.  The programming end of the project gets deep fast for a person with little to no programming experience.

Curt
After thinking about it, I think a standalone breakout board might be your best bet anyway.  It's only 4 wires to connect to Moteino and you'll have much more flexibility on placement (AND it's turnkey!).

I'll PM you with my address.  If you send me one of the BMP180 breakouts I'll be able to cook up some code and test it (not in a sailplane, I'm afraid) and post it when I'm done.  I mis-spoke in my previous post about the ease of programming, I was looking at the code posted on the site and, yes, you'd only have to change the LED definition, but that code did not include the communication with the radio...  That might take a few more lines of code  ;)

Bear in mind that the BMP180 is MUCH slower sampling time so there will be a noticeable lag and inaccuracy in readings as a result.

Tom

cgetman02

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Re: Moteino Variometer for RC Sailplanes
« Reply #7 on: February 13, 2015, 05:46:04 AM »
Tom,  I will get a couple of BMP180 in the mail today and have a MS5611 on the way to you also.  Have fun and let me know what you find out when you have time.

Thanks, Curt

http://www.embeddedadventures.com/barometric_pressure_sensor_module_mod-1009.html

TomWS

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Re: Moteino Variometer for RC Sailplanes
« Reply #8 on: February 21, 2015, 10:58:16 AM »
With the assistance of cgetman02, I've put together a working version of a Moteino based Variometer. 

It consists of two subsystems, one, the altimeter function is mounted in the Sailplane and transmits pressure readings to a Moteino based GroundUnit.  The GroundUnit converts the pressure and pressure variations into a frequency modulated tone that the RC Sailplane pilot can use to determine rate of climb (or fall).

The main basis for the code is from a blog referenced earlier in this thread, but included here for completeness: http://www.rcgroups.com/forums/showthread.php?t=1749208

The code was used practically unchanged, other than remapping I/O, splitting the function between the two devices, and adding the Moteino radio code.

I've bench tested this.  I'll leave it up to cgetman2 to take it flying  :D

Attached are the two schematics and a zip file with the code.  Enjoy and, as always, ask questions...

Tom

cgetman02

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Re: Moteino Variometer for RC Sailplanes
« Reply #9 on: March 04, 2015, 04:23:53 AM »
Tom, Thanks again for all your help on the vario project.  I still haven't had a chance to make any progress on it.  There isn't enough left of me after the OT i've been working.  Guess I'd better enjoy it while it lasts.

Maybe Friday I'll get to work on it.  My first day off and the weather looks like it's going to be crappy for flying.  Saturday I'm off of work also but a bunch of us are headed to a huge RC swapfest in Perry, GA.  Then back to the grind on Sunday I suppose.

I'll let you know when I get a chance to make some progress on the project.

Thanks again,  Curt