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Arduino Focus control and Cloud sensor


ncjunk

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Just an update for anyone who is interested.

Finally got the Arduino board working with an Easy driver stepper module and a 200 step stepper motor.

I managed to get it working with Focus max and had it controlling the focus all night between filter changes with ACP observatory control.

I now need to make sure it works ok for a couple of other people using the software and tidy up the code.

The Cloud sensor is hooked up to the SDA/SCL pins on the Arduino and is providing Ambient temp and Object temp (In this case the sky). The sensor is an MXL90614 and is a great little device that just works...I am putting it down to magic or little elves myself and it is cheap!

Over the next week I am going to record the Sky temperature to determine values for temp with clouds and without clouds...this may take a while as it depends on the weather.

Finally need to update the manual and write descriptions for each section of code.....oh and add in some dew control that Reggie has written.

Still, all good fun and I will get there slowly.

added a picture of the software so far.

:D

post-14473-133877454545_thumb.jpg

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  • 1 month later...
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Just set the Cloud sensor up outside to record some data (as long as the pc doesn´t fry in the heat). This is a graph of half an hour from this morning showing ambient and Sky temp where 2500 = 25.00 deg c.

Sky temp was showing -3.6 and ambient 21. It is now reading Amb 28.89 and sky temp -4.77.

The jump in the graph is where I took the sensor out of the shed at set it up (so initial values are shed temperature values)

It looks like we have sun and 30 odd deg for the next week at least so it may be a couple of weeks before I see enough cloud to get some decent readings. It looks good and the levels for no-cloud should be easy, it will be the different levels of cloud cover that will take a bit of working out.

post-14473-133877465263_thumb.jpg

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Hi, Just expressing an interest and a thanks for posting . Took me a little while to dig about and find Melexis for the MXL90614 data sheet as Google made it harder than the usual ! For anyone else looking Melexis: Hall-effect Position Sensors | Sensorless BLDC Motor Drivers

Can you suggest a UK source for the device ? I use Rapid,Farnell & ESR currently

I am in to 'big angle' sky clearance notification for meteor work and wide angle astrophotography . I currently rely on my age , liquid intake ( with it's consequence ) and a look out of the window because I am then half awake & need to attend to the call of nature :mad: !

Have you chosen your specific device for a particular sky angle ?

Len E

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Hi Len,

I chose the devise as it was the only one I found with the IR range that I needed and it also had everything built in so I only needed to add a couple of resisters and connect the comms to an Arduino.

I don´t know any uk distributors as I live in spain so only searched for sellers over here, I bought it from:-

Sensor de temperatura MLX90614

They have a lot of information on it as well.

It looks like the one I have has the wide FOV and I am initially going to use it to tell me if it has become partially cloudy. This is because I run my setup automated so that if it becomes cloudy I tend to pack it all away.

The circuit diagram is as per the one on Bricogeek with the SCA SCL comms hooked up to the same pins on the Arduino and a little bit of comms code.

The data sheet has the FOV information on page 30 figure 19, 20 ,21 etc

Any other questions then let me know.

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As an aside I found google a bit of a pain when searching for the mxl 90614...on my iphone it didn´t appear when i searched! there is not much on it but i found out after i bought it that it is the one used in a commercial cloud sensor so i think my choice was the correct one.

Thanks George!

That BAA version will give you a wide enough field of view.

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I will knock one up now!....actually...just going to check in the high tech tupperware container that it is sitting in...

What version of the arduino do you have George? (pin out is slightly different on each)

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Pin out is attached, I used word so there are no little dots signifying that there is an electrical connection between the wires but I think it is still obvious...hopefully!

If you need the code I can send you that as well...I have added it to the Arduino focus control driver.

Microsoft Word - MXL90614 IR sensor connections.doc.pdf

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Hi Neil,

Thanks for your circuit diagram, it was really useful! Is there any chance you could share your arduino code? Or even a nudge in the right direction. At the moment I'm just trying to get the sensor to take some readings but it won't even write to the serial monitor. :mad:

Thanks.

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Check it out here:-

http://tech.groups.yahoo.com/group/sgl_observatory_automation/files/Cloud%20Sensor/

I have added the Arduino code I am using along with a word doc which colour codes the sections of code to Comms, Focus, Cloud and something else!!

You will also need to search online for "i2cmaster" and download the zip file.

Peter Fleury Online: AVR Software

Then create a directory called i2cmaster under the Arduino--Hardware--Libraries directory and copy the files i2cmaster.h and twimaster (change the file type of twimaster to .cpp).

Mine is under Documents--Arduino--Hardware--Libraries.

You can then run then arduino and if you do serial monitor and send the command #TMP:00; and it will send you back the temperature...and a load of other rubbish.

Let me know if you have any problems.

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WOW! Thanks Neil. All I have to say is that's awesome. It turns out that my major issues were springing from the fact that the person who gave me the ir sensor had soldered the wires on the wrong way and I hadn't realised... Ooops. Your setup looks seriously impressive though, nice job!

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  • 1 month later...

Hi all,

Just found this post and was wondering how the progress has been on the Cloud Sensor.

Was wondering if anyone was able to make me up a working package (for a price of course) as I am hopeless with software etc.

Even step by step instructions would be great!

I am running WinXP and need a robust unit that can withstand the harsh daytime sun down here in NZ.

Also wondering if any one has attempted making a sensitive rain sensor?

Please contact me off list at email one@xtra.co.nz

Any help and info much appreciated.

Thanks. Regards, Tony.

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No progress from me as i started work again and its a bit manic. The problem is i am away from home so cant test anything :-(

I need to understand what ir values equal cloud or if i just have to look for a large change in values.

I might see if i can set it up and leave it running while away.

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  • 2 weeks later...

Blimy...I have no idea on SNMP so looks like I am going to have to do some reading!

I obtained a lovely graph of ambient temp vs sky temp on tuesday night which shows first high cloud (sky temp rises slightly) coming in then shows heavy cloud (sky temp equals ambient temp). Shown below.

post-14473-133877488657_thumb.jpg

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Great. I wasn't able to stop myself from ordering an Arduino 2009, LCD shield, Ethernet shield and one of these MXL90614 sensors.

The idea is to build an SNMP capable weather station.

We can work together if you want, Neil. ;-)

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No problems...although I have a list of things as long as my arm to do and very little time so don´t get too annoyed if I take a while to reply!

Problems with the MXL90614 are that using its ambient temperature reading will make cloud sensing during the day difficult (it will read the temperature of the case which will cause problems), but for night time stuff it will be fine.

The other points are along the lines of how does the above graph change if the ambient temperature is below freezing when cloudless or if the ambient temperature is 20 + deg when cloudless (that happens here quite a bit during the summer here 24 odd deg at night)...and then cloud rolls in.

but I will keep plugging away at it!

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No problems with the possible delays. Currently I'm waiting for the Arduino to arrive anyway. I ordered if from China cause it was cheaper .. ;-)

I've had a brief look at the API stuff and I do think I could do that. But I thought it wouldn't make sense for me to start a separate project when you have already started something. Would make much more sense to combine efforts.

In the long term this could be a project evolving in a complete-ish weather station. We could add support for more sensors (humidity, atmospheric pressure,rain ...). There could also be a separate temperature sensor that is located in the shade near the ground. That might get around the problem you describe with the IR sensor.

There could also be support for controlling relays according to certain conditions, e.g. when there is cloud and/or rain the relay could park the scope, close the obs roof, stop imaging and so on....

Then, via SNMP, the weather conditions could be read from the station, logged into a database and displayed as a graph over time.

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