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Old Nov 22, 2010, 07:02 AM
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Joined Jan 2009
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New Product
openaltimeter

I've been working on a new altimeter, with a load of features specifically for DLGs. I've put a website up about it:

http://openaltimeter.org

I think it's pretty cool It's a logging altimeter, it reads out your launch height at the field, it's a lipo regulator, and a low voltage alarm, and a lost model alarm! Also, all the software - the firmware and the download/graphing app - is open source, so you can customise it to your heart's content!

At the minute I'm beta testing with the help of a few hardy souls, but I'm planning on getting a production run made towards the end of the year and would like to gauge interest. There's a pre-order sign-up on the "Buy" page of the website. Stick your name down if you're interested! I'm aiming at about $65-70 per unit, but can't make any promises until I've got a firmer idea of numbers.

openaltimeter - introduction (4 min 57 sec)


Any comments/criticism very gratefully received!


Jony
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Last edited by JonyEpsilon; Nov 22, 2010 at 07:14 AM. Reason: Added video
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Old Nov 22, 2010, 07:44 AM
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Good luck

[QUOTE=JonyEpsilon;16616799]I've been working on a new altimeter, with a load of features specifically for DLGs. I've put a website up about it:

http://openaltimeter.org

I think it's pretty cool It's a logging altimeter, it reads out your launch height at the field, it's a lipo regulator, and a low voltage alarm, and a lost model alarm!

Jony

What a great idea, and at a competitive price. Count me in. I sent you an email.

Alan
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Old Nov 22, 2010, 08:43 AM
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Sounds like a great product idea!!

I will monitor this thread and will add your info to the "altimeter links" sticky thread when you get things up and running...
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Old Nov 22, 2010, 08:55 AM
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i'm really interested by your project...

exactly because your are giving a very good solution of what we need, and where also there is nothing in the market!!!

i'm not a expert, but 1A for the regulador looks maybe a little bit short.
for example:
the DS09 can consume up to 0,5A..... so if you have 5, even if they will not be fully used at the same time, but 1A can be easily reach, no?

best regards and success

Benjamin
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Old Nov 22, 2010, 09:18 AM
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Hi Benjamin,

The datasheets for the recom unit seem to suggest that they can hand peak currents of 2amps for a short period (i think)

I have been one of the beta-testers for the openaltimeter, and have used the device in a model with 2x JR 281 and 1x futaba 3154 (all digital servos) The regulator has never missed a beat... I have also looked at the voltage logs (the device logs altitude, battery-voltage and temperature) and there do not appear to be any worrying voltage drops when I am using high loads (such as landing flaps)
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Old Nov 22, 2010, 09:34 AM
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I'm interested in your project as well.
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Old Nov 22, 2010, 09:56 AM
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The data sheet from Recom is a bit... hmm... conservative, if this word works as expected in english like in german.
I'm using 1A Recom regulators for 4 digital Servos, 2xDS09 and 2xDS281 in one bird and 2xHS5045 and 2xDS281 in another one, without problems. You have to keep in mind that this regulators are made also for medical applications and i have the feeling that this is why the data sheet is very restraining.
From the Recom regulator point of view our "high" peek loads are very short. The regulator is highly over loadable and all you get is a bit more noise on the output.
If you are looking for a reliable easy to use regulator, use this.

lg

@Jony

Very nice Project!

You are using the BMP085 pressure sensor. As far as i know all this sensors are a bit light sensitive so i would put a piece of black paper over the surface.
What your project lacks of is a electronic On/Off switch. Maybe we should talk about that...
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Old Nov 22, 2010, 09:56 AM
flying is not a dream
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thanks for the info....

what is the sample rate for the altitude?


very interesting project
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Old Nov 22, 2010, 10:58 AM
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Quote:
Originally Posted by lebenj View Post
thanks for the info....
what is the sample rate for the altitude?
very interesting project
You can set the sampling rate yourself from the firmware, from the datasheet the sensor can handle up to 128 samples per second.

Because of the decent size of the logging memory you should still get at least a couple of hours worth of data at 1/10th second sampling
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Old Nov 22, 2010, 11:22 AM
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Here are a few comments about the openaltimeter I made on the flyquiet.co.uk forum.. works easier if I copy them across here rather than cross-linking..........

I've been lucky enough to have a beta version of this altimeter to test. I have used the version that includes the lipo regulator. It is a fantastic device that I am sure will become an essential piece of kit for all of us.

In the tight confines of a DLG fuz, it is such a pain if you have to start adding separate components to
- regulate the lipo
- get altimeter data
- get a low voltage alarm
- find my lost model (this would have been so useful for me in delmenhorst this year... and no doubt for Nick on his trip to the cornfield in Belgium.!!)

It has never been realistic to fit more than one or two of these devices to a model because it just gets too heavy and too cramped in the cockpit!

So now we have a device that puts all these devices in one small, neat package... but more importantly the openaltimeter does all of these individual functions better than any of the other dedicated devices I have tried.

Lipo Regulator -
The (optional) switching regulator used for the lipo is much more efficient than any other regulator I have tried. My battery life using these regulators is significantly better.. You can also use lower capacity 3s lipos just as easily as a higher capacity 2s version... just find the form-factor that suits.. Because the regulator is switching, it is not having to dissipate so much heat as linear regulators.. meaning I can now fly all afternoon on just one charge!

The other thing that is great about this device is that it also Logs your battery voltage, so you can see how your battery is discharging over the time you fly and also check out if you are getting any worrying voltage drops when the servos are doing a lot of work.

Altimeter -

Over the last couple of years, I have been using a very good "instant" readout altimeter from another vendor. I like instant readouts as they are fantastic for perfecting launch techniques and trims on the field.... and there is no need for a laptop-or PC to download the data in order to analyse it. As an "instant readout" altimeter the openaltimeter improves things further. Now I do not need to make a small hole in my fuz to poke the readout LED through, I can simply flick a switch on my transmitter and get the data from the audible tones.

As a recording altimeter things are improved over any other device I have used. Not only is altitude recorded byt also temperature and battery voltage... and the memory capacity means that I no-longer have to worry about high sampling rates filling up the device too quickly. I can sample at 1/5 second intervals for several hours to give a real high detail view of what is happening on a launch.

The software for downloading and displaying data is already highly functional and as it is also opensourced the community will be able to enhance it with all the features we can imagine.

lost model alarm

simply does what it says on the tin, you can program it to play your own music... how good would it be to switch on the dam-busters theme as you cruise back over the pits at the German open!!!

low-voltage alarm

Again this can be customised, so you can set the level of the alarm. You can also program the unit to give an audible readout of the current voltage as well as altimeter how-high information.

Opensource

The most exciting thing about this product is that it has been "opensourced"... for those who are not familiar, this means that the software that sits on the openaltimeter has been released for all of us to use and more importantly modify. As a community we can update the software to add features (such as hight-limiting code for e-soarers, GPS interface for cross-country flights etc etc).

All of my models will be using one of these devices from now on... after testing the beta-release of the openaltimeter, the device is now as essential as my reciever, battery and servos!!!

Congratulations to Jony for designing such an amazing bit of kit !
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Old Nov 22, 2010, 11:23 AM
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I like the fact that no switch-jack is built into the unit. One issue I have with regulated switch-jack units is that the jack port location limits where you can place the unit.

It also needs to be considered that the outputs of this device must be accessed to get the altimeter hooked to a computer....if a jack was built into the board and then mounted to the plane access to the outputs would probably be a pain.

My bottom line is that this unit looks to me to be just about perfect in terms of size weight and functionality options. An on/off switch can easily be wired into the system by the end user.
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Old Nov 22, 2010, 12:01 PM
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Looking good Jony! I will be watching...
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Old Nov 22, 2010, 02:21 PM
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JonyEpsilon's Avatar
London, UK
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Quote:
Originally Posted by lebenj View Post
i'm not a expert, but 1A for the regulador looks maybe a little bit short.
for example:
the DS09 can consume up to 0,5A..... so if you have 5, even if they will not be fully used at the same time, but 1A can be easily reach, no?
I can echo what the others have said: the Recom has an output current limit of 3A, but is only good for 1A average. I haven't done any testing to determine how far, and for how long, they can be pushed, but I don't think it's much to worry about. If you've stalled all four servos in your model you've probably got more to be concerned about anyway!

I've been flying the regulators in models with three digi servos (rudderless) for around a year and have had no trouble yet.


Jony
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Old Nov 22, 2010, 02:33 PM
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Quote:
Originally Posted by maikoflyer View Post
You are using the BMP085 pressure sensor. As far as i know all this sensors are a bit light sensitive so i would put a piece of black paper over the surface.
What your project lacks of is a electronic On/Off switch. Maybe we should talk about that...
Thanks for the tip about the black paper - it's pretty dark in my DLG pods, but it might be something to watch out for. (I did prise open one of the sensors a while back, as I was curious as to why this might be the case - pic attached).

I did make some prototypes with switchjacks built in (mechanical, not electronic) but I decided against it for exactly the reasons Nathan mentions. I've still got twenty of so PCBs lying around if you want one



Jony
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Old Nov 22, 2010, 02:45 PM
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Quote:
Originally Posted by LebenJ
what is the sample rate for the altitude?
As Richard says, it's configurable in the firmware. If you're careful with the code you should be able to get about 200 samples/per second out of the sensor, but you'll lose a little bit in resolution at this speed. The flash memory throughput (~140kb/s write) and the processor are fast enough that they don't limit the rate.

Quote:
Originally Posted by Richard S View Post
Because of the decent size of the logging memory you should still get at least a couple of hours worth of data at 1/10th second sampling
At high sample rates the samples will be pretty highly correlated, so there's probably a lot to gain from using a difference-style encoding, which could boost the memory capacity significantly. This might be something that will help even at a couple of samples per second, and is something I'm planning on looking at pretty soon in the firmware. [I've figured out how to double the storage pretty easily, but reckon I can get more!]


Jony
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