SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Jan 07, 2013, 05:23 PM
Registered User
mike_o's Avatar
Denmark, kbh
Joined Jan 2012
1,600 Posts
Warning: MAX7456 Ebay seller

Just ordered a 5 pcs of MAX7456 from ebay seller "polida2008" and received this mail:

"Hello,Could you kindly pay extra USD3.50 as registration fee?The parcel that shipped to Denmark may lost on the way, or it takes a long time to arrive there.What’s more,the post office may delay the regular mail.In order to track the parcel and make sure it arrive successfully, I hope you can pay it. If you don't accept it, I am afraid that it might lose.Hope you can understand. Waiting for your early reply."

I haven't met this behaviour on Ebay in any of my 400+ transactions before, and I have notified the seller that I consider this scamming. I suggest you avoid him for now.
mike_o is offline Find More Posts by mike_o
Reply With Quote
Sign up now
to remove ads between posts
Old Jan 07, 2013, 06:20 PM
HOL
Registered User
Danmark, Midtjylland, Galten
Joined Oct 2011
36 Posts
Thanks for the heads up, Mike. What a jerk. Never experienced that either.
HOL is offline Find More Posts by HOL
Reply With Quote
Old Jan 07, 2013, 06:47 PM
Registered User
bob4432's Avatar
United States, AZ
Joined May 2010
1,826 Posts
Dennis,

I would look at how they are doing it in MultiWii as people were upset with a deviation of 3-6ft @ ~20ft or so, but multis don't go that high. MW for the most part moved to the ms561101ba03 which supposedly has an accuracy of 10cm (not sure over that much altitude), but I have never looked at the code and haven't flown the latest MW due to other life responsibilities. You may want to ask over at the MW forum and see what they see as the MW will fly fixed wing, or even how they do it in AutoQuad software. I know AQ is using a different baro, but you could see the method. Same w/ OpenPilot/CopterControl Revo - may want to look at their baro code too as they use the ms561101ba03 too.

Sorry I can't be of more assistance,
bob

Quote:
Originally Posted by Dennis Frie View Post
Just did a few tests for altitude estimation with pressure sensor:
I can't really find a "light" approximation that gives an accurate result.
https://dl.dropbox.com/u/3947315/Pre...estimation.pdf

90 meters deviation at 2000 meter is quite a bit. Could be acceptable, but if anyone have some good suggestions please share
bob4432 is offline Find More Posts by bob4432
Reply With Quote
Old Jan 07, 2013, 08:23 PM
Registered User
United States, AZ, Prescott Valley
Joined Feb 2012
178 Posts
Dennis,

Received a BMP085 today - also, apparently a MAX sample or 2? is on its way to me

Maybe you have seen this regarding the BMP085 and the MS5611 ?

Copied below are a few user comments from the Sparkfun site regarding the BMP085
https://www.sparkfun.com/products/11282
It appears the site also includes some code
=====
RE: “accuracy down to 0.03 hPa”, from the data sheet I believe the noise is 0.03 hPa, not the accuracy. The typical absolute accuracy is given as +/– 1 hPa, or roughly 8 M altitude, the relative accuracy is +/– 0.2 hPa, or about 1.6 M altitude
=====
This agrees with what I’ve seen in the lab; the noise in the readings is on the order of 1 meter but if you can deal with lower data rates (< 1Hz) it filters down quite nicely.
=====

Are you are interested in working with the MS5611-01BA ? If so, I'll send you one.
And Fabs FreeIMU library - 2012/11/22 has some recent code work with the MS5611 -
http://www.varesano.net/projects/hardware/FreeIMU#0.3.5
RickEis is offline Find More Posts by RickEis
Reply With Quote
Old Jan 07, 2013, 08:50 PM
Registered User
bob4432's Avatar
United States, AZ
Joined May 2010
1,826 Posts
RIP Fabio
bob4432 is offline Find More Posts by bob4432
Reply With Quote
Old Jan 08, 2013, 04:21 AM
Registered User
jalves's Avatar
Portugal
Joined Mar 2004
2,641 Posts
Dennis,

Check this paper.
It could somehow help you.
jalves is offline Find More Posts by jalves
Reply With Quote
Old Jan 08, 2013, 06:36 AM
Registered User
Joined Dec 2012
35 Posts
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 ...
Tang0au is offline Find More Posts by Tang0au
Reply With Quote
Old Jan 08, 2013, 08:13 AM
Just another user
Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
Joined Feb 2011
1,086 Posts
Quote:
Originally Posted by mike_o View Post
Just ordered a 5 pcs of MAX7456 from ebay seller "polida2008" and received this mail:

"Hello,Could you kindly pay extra USD3.50 as registration fee?The parcel that shipped to Denmark may lost on the way, or it takes a long time to arrive there.What’s more,the post office may delay the regular mail.In order to track the parcel and make sure it arrive successfully, I hope you can pay it. If you don't accept it, I am afraid that it might lose.Hope you can understand. Waiting for your early reply."

I haven't met this behaviour on Ebay in any of my 400+ transactions before, and I have notified the seller that I consider this scamming. I suggest you avoid him for now.
Quote:
Originally Posted by HOL View Post
Thanks for the heads up, Mike. What a jerk. Never experienced that either.
Year, thanks for the hads up! I would find another seller and fill a complaint on ebay or similar, if he don't ship the items at the price advertised.
Quote:
Originally Posted by bob4432 View Post
Dennis,

I would look at how they are doing it in MultiWii as people were upset with a deviation of 3-6ft @ ~20ft or so, but multis don't go that high. MW for the most part moved to the ms561101ba03 which supposedly has an accuracy of 10cm (not sure over that much altitude), but I have never looked at the code and haven't flown the latest MW due to other life responsibilities. You may want to ask over at the MW forum and see what they see as the MW will fly fixed wing, or even how they do it in AutoQuad software. I know AQ is using a different baro, but you could see the method. Same w/ OpenPilot/CopterControl Revo - may want to look at their baro code too as they use the ms561101ba03 too.

Sorry I can't be of more assistance,
bob
Thanks. I'll play a bit with it myself and have a look at how it's done in other projects if I get stuck
Dennis Frie is offline Find More Posts by Dennis Frie
Reply With Quote
Old Jan 08, 2013, 08:23 AM
Just another user
Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
Joined Feb 2011
1,086 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

Maybe you have seen this regarding the BMP085 and the MS5611 ?

Copied below are a few user comments from the Sparkfun site regarding the BMP085
https://www.sparkfun.com/products/11282
It appears the site also includes some code
=====
RE: “accuracy down to 0.03 hPa”, from the data sheet I believe the noise is 0.03 hPa, not the accuracy. The typical absolute accuracy is given as +/– 1 hPa, or roughly 8 M altitude, the relative accuracy is +/– 0.2 hPa, or about 1.6 M altitude
=====
This agrees with what I’ve seen in the lab; the noise in the readings is on the order of 1 meter but if you can deal with lower data rates (< 1Hz) it filters down quite nicely.
=====

Are you are interested in working with the MS5611-01BA ? If so, I'll send you one.
And Fabs FreeIMU library - 2012/11/22 has some recent code work with the MS5611 -
http://www.varesano.net/projects/hardware/FreeIMU#0.3.5
The measurements I've done gives quite a lot more noise than written in the comments on Sparkfun. Nevertheless, I probably have to use higher samplerate and filter the data more then first expected.

Your BMP085 will be detected when you connect it, but it's most likely quite useless until next update - sorry.

At the moment I still have plenty of testing and implementation to do, but in the future it might be interesting to compare with MS5611-01BA.
But lets start with the current hardware

Quote:
Originally Posted by bob4432 View Post
RIP Fabio
Really a shame with Fabio. He was a great person and his contributions to this community have been quite impressive.

Quote:
Originally Posted by jalves View Post
Dennis,

Check this paper.
It could somehow help you.
ll have a look at it., thanks!
Dennis Frie is offline Find More Posts by Dennis Frie
Reply With Quote
Old Jan 08, 2013, 08:33 AM
Registered User
Joined Sep 2010
2,425 Posts
Whats up with Fabio??
msev is offline Find More Posts by msev
Reply With Quote
Old Jan 08, 2013, 08:36 AM
Just another user
Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
Joined Feb 2011
1,086 Posts
Quote:
Originally Posted by msev View Post
Whats up with Fabio??
He passed away...
http://www.rcgroups.com/forums/showthread.php?t=1794989
Dennis Frie is offline Find More Posts by Dennis Frie
Last edited by Dennis Frie; Jan 08, 2013 at 08:51 AM.
Reply With Quote
Old Jan 08, 2013, 08:41 AM
Just another user
Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
Joined Feb 2011
1,086 Posts
Just to give you an idea of the noise on BMP085


The Y-axis is 70 pa ~= 6 meter
Dennis Frie is offline Find More Posts by Dennis Frie
Reply With Quote
Old Jan 08, 2013, 08:49 AM
Registered User
Joined Sep 2010
2,425 Posts
Wow thats a shock about Fabio...He was soo young :/..Thanks for letting me know.
msev is offline Find More Posts by msev
Reply With Quote
Old Jan 08, 2013, 09:28 AM
Just another user
Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
Joined Feb 2011
1,086 Posts
Oversampled (red) and digital lowpass filtered (blue)
Dennis Frie is offline Find More Posts by Dennis Frie
Reply With Quote
Old Jan 08, 2013, 10:15 AM
Registered User
United States, AZ, Prescott Valley
Joined Feb 2012
178 Posts
Quote:
Originally Posted by Dennis Frie View Post
Oversampled (red) and digital lowpass filtered (blue)
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
RickEis is offline Find More Posts by RickEis
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