A libre breakout board for the MS5611-01BA high resolution altimeter sensor
As a first step in the development of FreeIMU v0.4, I'm starting my first steps with the MS5611-01BA high resolution altimeter sensor. According to its datasheet, this chip looks extremely accurate as it's capable of a 10 cm resolution in altitude estimation.
I already sorted out most of its electrical connections when I drafted the first designs of FreeIMU v0.4, however I wanted to start testing it before having FreeIMU v0.4 PCBs ready, just to start experiencing a little with it.
So, I designed a very simple breakout board for it. I tried to keep the design as simple as possible to allow etching a PCB from it, something I'll try in the next days. For this design I choose to use the I2C bus as it's the one I'm more experienced with, however the chip also supports SPI.
You can find the schematics in the attachments below. The KiCAD designs of the breakout board for the MS5611-01BA, released under CC-BY-SA, on my personal repository using Bazaar (bzr), with the following command:
bzr co http://repository.varesano.net/LibreBB_MS5611-01BA/
Below a picture of it.
| Attachment | Size |
|---|---|
| LibreBB_MS5611-01BA_schematics.pdf | 20.78 KB |
blog bug? spam? Why do I get this email?
Every day or two I get an email from website [at] varesano [dot] net with notice of a post to this thread. The contents always say say:
>Reilstistaks has commented on: "A libre breakout board for the >MS5611-01BA high resolution altimeter sensor"
When I click the link I get taken to the top of this thread and there is no such post from that user. Is this some kind of spam that gets filtered out before I get here? Or is this some kind of bug in the blog software?
Any luck with this board? Did you get it soldered? I saw the fail picture. It made me reluctant to try to do this myself. A tough to solder part is probably not a good candidate for a first home built board.
Sorry
@zencuke I'm sorry for the spamming.. Unfortunately there is someone who's posting repeatedly spam on this article. I do have a filtering system setup but somehow this guy is always successful posting the spam.
As you have subscribed to the notification, you get notified, but, as I usually delete such spammy comment in a matter of hours, so once you click on the email which you received it points to a comment no more available.
I would suggest unsubscribing to this article until I find a solution to this spammy problem. There should be an unsubscribe link in the bottom of the notification email.
Yes, I've been successful soldering and using this chip! See MS5611-01BA Arduino library: first developments results.
MS5611 sourcing
If you are looking for MS5611 parts I suggest you try the following sources:
1) USA: www.servoflo.com contact David Ezekiel david [at] servoflo [dot] com
2) EU: www.amsys.de contact Norbert Rauch vertrieb [at] amsys [dot] de
3) APAC: www.everestpacific.com contact Kenny Yip kenny [at] everestpacific [dot] com
Not listed on web sites. Use the contacts.
None of these three sites list the MS5611 on their web pages. At least i couldn't find it. You will need to follow through with the listed contacts to order it. It appears to be a very new part so hasn't made it to the online catalogs yet.
That is the good news. Being new it will probably not get end-of-life'd for the next month or two. ;-)
Thank you Rob for the
Thank you Rob for the pointers. I've got mine MS5611-01BA from www.amsys.de as I'm in Europe, I can highly recommend them.
Meas sensor soldering...
Hi Fabio
Have you by any chance studied the application notes for the MS5611-01BA sensor.
It looks like its a bit picky with the soldering process:
http://www.meas-spec.com/downloads/Soldering_of_Sensors.pdf
I am not having much luck with KiCad these days. Could I persuade you to export a hires PDF (mirrored) of the copper layers. I will try my hands at making some breakouts using toner transfer method!
Thanks
Jussi
Hey Jussi, sorry for the late
Hey Jussi, sorry for the late reply.. I was out of Italy on holidays! ;-)
I just had a quick look to the soldering notes.. I didn't see anything strange about it.. what does concern you exactly?
I must have misread the
I must have misread the soldering temps. I see that peak is 225 celsius for 10-30 seconds. Hard, but not impossible...AG paste would be necessary (At least if you still are Adamant about ROHS-compliancy)
Me, I would just use 66/33 lead paste for prototyping! I dont like to work with the ROHS stuff and the fumes from the ROHS-compliant fluxes are even more nasty than those coming from rosin-based fluxes!
This worries me a bit. But a piece of Kapton tape would probably be a good idea anyway, to protect the sensor openings and the sensor itself from hot air during soldering
The MS5611-01BA has been manufactured under cleanroom conditions. It is therefore recommended to assemble the sensor under class 10’000 or better conditions. Should this not be possible, it is recommended to protect the sensor opening during assembly from entering particles and dust. To avoid cleaning of the PCB, solder paste of type “no-clean” shall be used. Cleaning might damage the sensor!
I see that your layout is 2-sided. I think I will bang out a singlesided version and make by toner transfer....
BTW: The Femtos arrived yesterday. Good work - Man, those things are tiny - trying to wrap my head around how best to make a connector for the FDTI. I assume you already burned the bootloader....
Ehm.. it looks like soldering
Ehm.. it looks like soldering this chip is harder than what I was expecting.. see First soldering experiment with the MS5611-01BA: huge fail!
I'll let you know as soon as
I'll let you know as soon as I reflow the first units if I encounter any issue.
I designed a 2 sided board because I'm using the same GND,VCC,SDA,SCL pin sequence for all my boards. It should be possible to go single sided by laying out the breakout pins differently.
Yeah, the bootloader is on the Femtoduino.. you'll find there the Arduino 2009 328p 16Mhz bootloader. Let me know how it goes with the Fememtos ;-) ..
making one off PC boards?
What process do you like for making one off development boards like this?
back side alignment?
Good I'll try that. I've never done my own PC board but it is about time I tried. Any tips for aligning the second side with the first? I was going to drill the through holes after the first side is done. I guess I should really look for an online howto for all this, including soldering SMT. There should be plenty to find.
I'm having trouble finding a source for these parts in the US. They seem to be pretty new. Where did you get them?
Thanks.
I'm getting them from
I'm getting them from amsys.de. You may wanna check the distributors for Measurement Specialties.
For aligning the top and bottom side I use a flashlight to see through the copper board. Let me know if I should clarify a bit more.
Regarding surface mount devices soldering I would suggest this video. Similar result can be achieved using a cooker.
Hope this helps.
Fabio
leading edge
Thanks for the suggestions and being helpful. I shouldn't pester you for general techniques I can find in online how-tos.
I find lots of distributors for Measurement Specialties but none seem to have this part in their online catalog. I usually go to Mouser or Digikey and neither have the part number listed. In fact I don't even see the MS5611 in AMSYS's web catalog on the barometric sensor page although the MS5607 is there. Maybe it is still in the samples only stage and you have to know to ask. I guess I'll start sending email to some distributors and see what they say.
I guess you are just a leading edge technologist, ahead of the curve! ;-)
Thanks again
It's that I'm actually living
It's that I'm actually living in the future..
I'm a big fan of press and
I'm a big fan of press and peel blue sheets and ferric chloride etchant .. gives good results with small efforts and equipments.
Hope this helps,
Fabio
True 6DOF starting to show up!!!!
Amazing! If you keep up thiis way, you´ll piss off Nitendo and Sony with a true 6DOF IMU, WITHOUT any external device, cameras etc...
Keep it up man, I´m a fan!
Wind sensor
Come to think of it I'll bet this device is sensitive enough to be turned into an acceptable wind speed sensor. Use two sensors, one pointed forward, one out of the wind someplace as a reference. Actually three properly placed sensors might measure 3D velocity and the average still gives altimeter readings. Hmm... Where is my pencil. Got to do a few calculations. 20 m/sec wind speed (my practical max on a bike) => 200 pascals => 2 mbar. This chip is spec'd at .042 mbar typical resolution. Am I doing that right? No dropped decimal points? Not spectacular and it gets worse at low speeds but probably close enough for government work. Pressure to wind speed has a bizarre mathematical relationship so this could take some calculation but I'm really interested in a headwind pressure estimate (for the power calculation) so I could skip that. Head wind pressure and climb rate should give a useful work done estimate if mass and cross sectional area is known. And just using this chip! (Well two of them anyway.)
Re: Wind sensor
zencuke,
this isn't the real speed! you need subtract the static pressure.
You are reading infact dynamic pressure+static pressure.
Check "Pitot-Tube" how-to and you learning more.
Have you a nice day.
Stefano
3D velocity?
Thank's for the tip Stefano but I thought that's what I was proposing. I'm afraid I was too terse and didn't make it clear. I suggested two sensors, one "facing forward" for the combined pressure and the other "out of the wind someplace" for the static pressure (I was thinking inside my bicycle bag for static.) I didn't use the terms dynamic and static but that is what I meant. Pitot tubes are set up to measure the differential directly with one sensor but that wouldn't work with this sensor. My plan was to measure both independently and subtract to calculate dynamic pressure. When I said the relationship between pressure and speed is bizarre and needs calculation I was thinking about Bernoulli's equation. I know that calculating the differential means calibrating the sensors against each other and adds another error term. Am I missed anything?
In fact it seems to me that this could be generalized to 3D. Three sensors in three tubes pointing in orthogonal directions. Average them to calculate the static pressure, subtract that from each and you have three components which should give you velocity. There is very little up and down component to wind on the surface but it might be handy to also know sideways wind pressure on my bicycle.
Well, it isn't easy to do
Well,
it isn't easy to do this!
First problem is about the sensor (pitot), this should be parallel to flow to measure the right forward speed (pressure).
Usually there are two sensor, one for dinamic (forward out of turbolence)and other for static (in a clear area).
In digital system a computer perfom a right correction; in analogic system the anemometer subtract in "mechanical way" the two pressure.
A lateral sensor don't read the right wind speed because the pitot conformation don't allow to read lateral pressure...
Try to think a system with two ultrasonic sensor. This run like Doppler sensor and shoud be able to read the lateral wind speed after forward speed subtraction. Yes it is a little bit cumbersome!
A tip: remember you measure a pressure and you convert to speed. To do this you must correct with air temperature!
Not difficult
Stefano,
It seems easy enough to me but maybe that's because I first applied Bernouli's principal in its simplest form many years ago to calculate the terminal velocity of a free falling body (sky diver,) a typical problem in the introductory physics class at my college. One of the more dramatic examples of lateral Bernouli forces I ever saw was on a sail boat of a friend. There was a hole in the bottom at the lowest point, well below waterline level, that had a removable plug. When water came over the side during a race he would pull the plug and the water would suck out with a very dramatic gurgle. That's what the hole was for. Water inside slowed the boat down, never good during a race. When the boat was stopped or going slowly pulling the plug would obviously have sunk the boat. That was a very fast boat with a planning hull that would climb right on top of the water and surge faster if there was enough wind... AND no inboard water. When in a race "surging faster" is a very good thing. ;-)
-zencuke
I'm etching some bobs for
I'm etching some bobs for this chip soon.. I also do have the raw chips now and I'll soon post about how this works!
Keep it coming
FreeIMU keeps getting better and better. Thanks. You are my hero. Pulling all this together for everyone and open source to boot.
This 4 chip sensor combo rocks. I predict that lot of things are going to happen with it in problem spaces you would never suspect. With a hi-res altimeter I probably wouldn't even need a power sensor which is good because power sensors are not easy. Strain gauges are simple in concept but hard to make work. (Need a follow on project? ;-)?) I was trying to figure out how to factor in hill climbing on my bicycle. I didn't realize pressure sensors were this sensitive. I'm already doing my own GPS. I guess I need to learn Kalman filters better so I merge with GPS altitude data.
Thanks for the kind words. I
Thanks for the kind words. I hope you find FreeIMU useful in your projects.
Keep following my blog for my future projects ;-)
Take care,
Fabio
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