HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Jan 08, 2013, 10:16 AM
Registered User
Joined Sep 2010
2,425 Posts
Looks promising...so how does the graph translate to variation in meters?
msev is offline Find More Posts by msev
Reply With Quote
Sign up now
to remove ads between posts
Old Jan 08, 2013, 10:20 AM
Just another user
Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
Joined Feb 2011
1,082 Posts
Quote:
Originally Posted by RickEis View Post
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.
Dennis Frie is online now Find More Posts by Dennis Frie
Reply With Quote
Old Jan 08, 2013, 10:24 AM
Just another user
Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
Joined Feb 2011
1,082 Posts
Quote:
Originally Posted by msev View Post
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.
Dennis Frie is online now Find More Posts by Dennis Frie
Reply With Quote
Old Jan 08, 2013, 11:02 AM
Just another user
Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
Joined Feb 2011
1,082 Posts
- 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
Dennis Frie is online now Find More Posts by Dennis Frie
Reply With Quote
Old Jan 08, 2013, 11:52 AM
Chilled and served
Henry.'s Avatar
Sweden
Joined Mar 2005
289 Posts
Wow, that is sensitive..
Henry. is offline Find More Posts by Henry.
Reply With Quote
Old Jan 08, 2013, 12:18 PM
Just another user
Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
Joined Feb 2011
1,082 Posts
Quote:
Originally Posted by Henry. View Post
Wow, that is sensitive..
Year, they are quite sensitive. But it does require some filtering and oversampling to get a descent result
Dennis Frie is online now Find More Posts by Dennis Frie
Reply With Quote
Old Jan 08, 2013, 12:34 PM
Just another user
Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
Joined Feb 2011
1,082 Posts
Quote:
Originally Posted by RickEis View Post
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.
Dennis Frie is online now Find More Posts by Dennis Frie
Reply With Quote
Old Jan 08, 2013, 04:31 PM
Registered User
bob4432's Avatar
United States, AZ
Joined May 2010
1,826 Posts
Quote:
Originally Posted by Tang0au View Post
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...
bob4432 is offline Find More Posts by bob4432
Reply With Quote
Old Jan 08, 2013, 04:39 PM
Just another user
Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
Joined Feb 2011
1,082 Posts
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
Dennis Frie is online now Find More Posts by Dennis Frie
Last edited by Dennis Frie; Jan 08, 2013 at 07:46 PM.
Reply With Quote
Old Jan 08, 2013, 04:56 PM
Just another user
Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
Joined Feb 2011
1,082 Posts
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.
Dennis Frie is online now Find More Posts by Dennis Frie
Reply With Quote
Old Jan 08, 2013, 07:52 PM
Registered User
United States, AZ, Prescott Valley
Joined Feb 2012
178 Posts
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
RickEis is offline Find More Posts by RickEis
Reply With Quote
Old Jan 08, 2013, 07:55 PM
Just another user
Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
Joined Feb 2011
1,082 Posts
Quote:
Originally Posted by RickEis View Post
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.
Dennis Frie is online now Find More Posts by Dennis Frie
Reply With Quote
Old Jan 08, 2013, 08:02 PM
Just another user
Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
Joined Feb 2011
1,082 Posts
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.
Dennis Frie is online now Find More Posts by Dennis Frie
Reply With Quote
Old Jan 08, 2013, 08:05 PM
Registered User
rimshotcopter's Avatar
United States, CA, Los Angeles
Joined Aug 2009
11,707 Posts
Quote:
Originally Posted by Dennis Frie View Post
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.
rimshotcopter is offline Find More Posts by rimshotcopter
Reply With Quote
Old Jan 08, 2013, 08:16 PM
Just another user
Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
Joined Feb 2011
1,082 Posts
Quote:
Originally Posted by rimshotcopter View Post
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?
Dennis Frie is online now Find More Posts by Dennis Frie
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Help! OSD version UNKNOWN and fail to update (error) dROb Eagle Tree Systems 9 May 16, 2012 06:12 PM
Sold EASY OSD (Version 1.2) Brand New . $75 shipped. LHTPlane FPV Equipment (FS/W) 7 Mar 20, 2012 11:45 PM
For Sale MAX7456 OSD Break out board. ziomatrixacs FPV Equipment (FS/W) 4 Jun 18, 2011 04:50 PM