humidity

Request new hardware or ideas for the controller
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gs33
Posts: 6
Joined: Fri Dec 16, 2011 3:02 pm

humidity

Post by gs33 »

it would be usefull to be able to monitor humidity above the aquarium , especially in the summer
dhave
Posts: 26
Joined: Tue Dec 06, 2011 12:01 am

Re: humidity

Post by dhave »

gs33 wrote:it would be usefull to be able to monitor humidity above the aquarium , especially in the summer
Yes, it will be usefull to star fan to remove it in close forniture with electric equipment.
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stevenhman
Posts: 23
Joined: Sat Jan 14, 2012 4:57 pm

Re: humidity

Post by stevenhman »

I asked a question similar to this using SHT15's - here is a response
I just read very briefly the datasheet and it says it uses I2C protocol.
If so, all of the expansion modules are built around I2C, so it would be just like another expansion module.
rimai
Posts: 12881
Joined: Fri Mar 18, 2011 6:47 pm

Re: humidity

Post by rimai »

After further investigation, it seems SHT15 is not what you want to use. You need SHT21 or SHT25.
The SHT15 doesn't really use I2C, but some weird protocol that no microprocessor understands and you would have to develop your own communication code.
This is in the SHT15 datasheet:
The serial interface of the SHT1x is optimized for sensor readout and effective power consumption. The sensor cannot be addressed by I2C protocol; however, the sensor can be connected to an I2C bus without interference with other devices connected to the bus. The controller must switch between the protocols.
And this is in the SHT21 datasheet:
SHT21 communicates with I2C protocol.
Roberto.
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jsclownfish
Posts: 378
Joined: Mon Oct 24, 2011 7:52 pm
Location: Saint Louis

Re: humidity

Post by jsclownfish »

Could it be done like this with the SHT15?
http://www.youtube.com/watch?v=gsrvT2odicI
-Jon
rimai
Posts: 12881
Joined: Fri Mar 18, 2011 6:47 pm

Re: humidity

Post by rimai »

Oh, I have no doubt that you could use that with an Arduino board.
Like I said, it uses some incompatible 2-wire protocol instead of I2C.
RA is all speced to work with I2C devices and the SHT-21/25 are much better choices because they can be integrated very easily. All you need is hook up to the expansion bus and you are done. Very little code is needed. All you basically need is Wire.requestFrom()
With the SHT-15, you would have to dedicate at least 2 pins just to achieve the same thing, plus the code overhead to use the sensirion library available on the arduino website or develop your own protocol.
I just don't see the benefit of using SHT15 over SHT21/25.
Roberto.
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