Diy osd (MAX7456 version, OpenSource) - Page 31 - RC Groups
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Jan 08, 2013, 09:16 AM
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Looks promising...so how does the graph translate to variation in meters?
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Jan 08, 2013, 09:20 AM
Just another user
Dennis Frie's Avatar
Quote:
Originally Posted by RickEis
Dennis,
This is so neat to be able to see these plots as you fine tune things. Do you mind taking just a few minutes explaining what you are using and how you plot this. I'm very interested !
Thanks,
Rick
I usually write a little test-sketch to test the individual sensor - that makes me able to concentrate on the single sensor.

By sending all the information over serial-communication, you can get some good visual presentation of the data. As you can see, the oversampling helps a lot, but requires extra delay. The lowpass-filter further removes noise, but also gives a slower response. Preferably I would use oversample and max sampling-rate, but the microcontroller also have a few other things to do.

At the moment I seem to have an acceptable stability in altitude - at least for testing.

I use a little program called "Serial chart" to visualize the data.
Jan 08, 2013, 09:24 AM
Just another user
Dennis Frie's Avatar
Quote:
Originally Posted by msev
Looks promising...so how does the graph translate to variation in meters?
Slowly getting there
The graph is 70 pa on the y-axis. 1 pa ~0.08 meter altitude. Not 100% accurate, but acceptable in a plane.

Can try a second order lowpass filter to maintain the time-constant bot get better filtering.
Jan 08, 2013, 10:02 AM
Just another user
Dennis Frie's Avatar
- Think we have an acceptable result.

Below the final altitude-estimation can be seen. At the graph below the pressure sensor was at the floor, raised ~2 meters, on the floor, raised ~2 meters and finally at the floor.
Not perfect, but at 2 meters deviation that's not too bad
Jan 08, 2013, 10:52 AM
Chilled and served
Henry.'s Avatar
Wow, that is sensitive..
Jan 08, 2013, 11:18 AM
Just another user
Dennis Frie's Avatar
Quote:
Originally Posted by Henry.
Wow, that is sensitive..
Year, they are quite sensitive. But it does require some filtering and oversampling to get a descent result
Jan 08, 2013, 11:34 AM
Just another user
Dennis Frie's Avatar
Quote:
Originally Posted by RickEis
Dennis,

Received a BMP085 today - also, apparently a MAX sample or 2? is on its way to me
Rick, let me know if you need the new software to use with BMP085. It's still quite new and untested, but better than the old version where BMP085 doesn't show altitude etc.
Jan 08, 2013, 03:31 PM
Registered User
bob4432's Avatar
Quote:
Originally Posted by Tang0au
also, the code used by the arducopter / apm might help - different baro sensor, but at least the code is open source, and they get accuracy of 10cm ...
they are just listing the spec for the baro they are using - the ms5611-01ba03, whether or not they are actually getting 10cm is another story...
Jan 08, 2013, 03:39 PM
Just another user
Dennis Frie's Avatar
New version have been uploaded
http://code.google.com/p/diy-osd-max7456/downloads/list

Not really good at remembering what was done in which version.

Anyway, the major difference is the sensors. This version should have a fully working implementation of BMP085 (at least ready for test) and the artificial horizon have been updated a bit.

If anyone get a chance to test BMP085 - please leave some feedback

Pressure-sensor and the bar have been fixed for NTSC too
Last edited by Dennis Frie; Jan 08, 2013 at 06:46 PM.
Jan 08, 2013, 03:56 PM
Just another user
Dennis Frie's Avatar
By the way. A separate folder is included with a sketch called "Character_Uploader".

It will upload all the default characters to MAX7456 + the modifications. This can be necessary if you have replaced the original characters on MAX7456, if you want to test with MinimOSD - or just if MAX7456 have received some weird data while programming Atmega328 with ISP.

Long story short - use it if necessary.

The character-upload in the default code have been changed to upload second time the Atmega328 boots. This is done to ensure the ISP-communication have been closed properly. Otherwise there is a good chance that the character-upload will fail.
Jan 08, 2013, 06:52 PM
Registered User
Hi Dennis,

BMP085 was detected

When I moved the copter off the file cabinet the elevation went down to -4 something...
so looked very good. Then went to close to zero when I put it back up.....

Need more time to test.....
Maybe Character_ Up-loader as the numbers in the number of satellites were messed up.

~ Could not detect PPM for some reason ?
~ timer seemed to get hung up
~ temp was in Celsius....don't know how to read that (just kidding...was surprised to see temp !)

Need to read the config.h file to see if you are testing my reading skills again.

more later,

Rick
Jan 08, 2013, 06:55 PM
Just another user
Dennis Frie's Avatar
Quote:
Originally Posted by RickEis
Hi Dennis,

BMP085 was detected

When I moved the copter off the file cabinet the elevation went down to -4 something...
so looked very good. Then went to close to zero when I put it back up.....

Need more time to test.....
Maybe Character_ Up-loader as the numbers in the number of satellites were messed up.

~ Could not detect PPM for some reason ?
~ timer seemed to get hung up
~ temp was in Celsius....don't know how to read that

Need to read the config.h file to see if you are testing my reading skills again.

more later,

Rick
Wow, that was quick you was able to test.
Celsius can be changed, but not really a priority

Weird with the timer and PPM. Need to do a few tests as that shouldn't happen. The timer runs on GPS-time if you have set that in config-file.
Jan 08, 2013, 07:02 PM
Just another user
Dennis Frie's Avatar
Just did a quick test, PPM is detected just fine with EzUHF here.

You should be aware that a corrupted I2C communication (disconnected BMP085) can result in a freeze - that's a problem with the wire (I2C) library.
Jan 08, 2013, 07:05 PM
Registered User
rimshotcopter's Avatar
Quote:
Originally Posted by Dennis Frie
Just did a quick test, PPM is detected just fine with EzUHF here.

You should be aware that a corrupted I2C communication (disconnected BMP085) can result in a freeze - that's a problem with the wire (I2C) library.
Why not use some code from the MultiWiiCopter, it is pretty solid at this point.

http://code.google.com/p/multiwii/so...ultiWii_shared

Look in the sensor.ino file.
Jan 08, 2013, 07:16 PM
Just another user
Dennis Frie's Avatar
Quote:
Originally Posted by rimshotcopter
Why not use some code from the MultiWiiCopter, it is pretty solid at this point.

http://code.google.com/p/multiwii/so...ultiWii_shared

Look in the sensor.ino file.
I need a new I2C routine at some point. Haven't really looked at it yet as the wire-library works - I just don't like the fact that it ends up in a infinite loop if a sensor is disconnected at the wrong time. I've considered a watchdog, but that doesn't work with default bootloader either.

Using the I2C from multiwii could be a possibility, but really don't wanna "take" any work from other people. Any idea about the license or who to contact?


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