Help with Temperature Controle


8 posts
by msloan » Tue Dec 11, 2012 7:58 pm
I am trying to figure this out but nothing is working. AHHHH, please let me know what I am doing wrong.

I have followed this guide:
http://www.cl.cam.ac.uk/freshers/raspbe ... index.html
and looked here:
http://www.trainelectronics.com/Raspber ... index.html
and here:
http://raspberrypi.stackexchange.com/qu ... /3609#3609

I have these sensors:
http://www.mouser.com/Search/ProductDet ... 60BIZ/NOPB
http://www.mouser.com/Search/ProductDet ... 19CIZ/NOPB

and these resistors:
http://www.mouser.com/Search/ProductDet ... -CFR16J4K7

When I try to wire up the sensor like thisImage
It gets extremely hot. I have to turn the sensor around so the round part faces out. The Ti documents also suggest that the ground is on the right when viewed from the bottom (opposite this picture).

When I try to list the device I only get:
w1_bus_master1

Do you need any more info to see what I am doing wrong?
Thanks
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Joined: Fri Feb 24, 2012 5:36 pm
by davadvice » Tue Dec 11, 2012 8:18 pm
hi,

by the sounds of it you have the sensor the wrong way round I done that to !! .

the Diagram is looking from Botom up not top down. look at the sensor with the legs facing you to get pin 1,2,and 3.

I did try to add an image of mine but dont have a host and cant seem to attach here !!


David
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by msloan » Tue Dec 11, 2012 9:28 pm
When I do switch it around, it heats up very fast. I have tried most of my sensors and all of them do this.
Are the parts I'm using OK to use?
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by davadvice » Thu Dec 13, 2012 5:03 pm
Hi I have Just looked over yours and checked with the GPIO diagram and the pins all look fine.

have you tested to ensure the resistor is making full contact across the pins and that it is at 4.7Kohm?

I would test each pin to the Female connection at the GPIO to make sure you have a resistance reading.

Do you have a multimeter ?

the way you have it connected in the pic looks fine.

Still cannot upload the image(too large i think)
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by johndpar » Fri Dec 14, 2012 1:33 pm
Hi

Well, the first problem is that the sensors you are trying to use are analog sensors, and the Pi does not have any analog inputs.

The articles you reference all use the Dallas/Maxim DS18B20 type digital "One wire" temperature sensors. These can work very well with the Pi, but are a very different beast to the analog sensors you are trying to use.

Time to buy the right sensors I think!

Regards

John
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by rurwin » Fri Dec 14, 2012 1:50 pm
I don't understand. You say you have some sensors, which are analogue sensors and would not work in that circuit. Then you post a picture of a Dallas 18B20, which is the correct (digital) sensor, connected correctly.
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by johndpar » Fri Dec 14, 2012 2:26 pm
Hi ruwin

You'll find the image is from the referenced stackexchange article, not his own setup!

John
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by davadvice » Fri Dec 14, 2012 3:34 pm
ahh makes sense now.

I thought it strange that when i looked at the image the part no was almost the same as mine !

never really paid too much attention to the parts list, we live and learn
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