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How to connect a thermistor to my MSP430 and other ?'s


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#1 Oscarasimov

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Posted 13 September 2012 - 06:40 PM

Hey guys, I'm completely new to micro-controllers and I'm having trouble using the search bar. I think I'm so clueless that most people are assuming basic knowledge that I don't have yet.

I'm trying to connect a thermistor to my MSP430 and read temperature. I found this post on in the projects section :


viewtopic.php?f=10&t=2524&p=18608&hilit=thermistor#p18608


It looks like its exactly what I want to do but I'm having trouble understanding what's going on here. ( What pins to connect the thermistor too? how to upload the code files onto the chip?)


I've been watching c programming tutorials on youtube but I'm not quite sure how to apply that to the MSP430.

Does anyone know a link or resource I can read that can explain this to me like I'm 5?

#2 artifus

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Posted 13 September 2012 - 08:27 PM

hello.

i'm new too and there appears to be quite a steep learning curve ahead, a few new concepts to absorb and a lot of jargon to take on board. best to take it slow and steady, every journey begins with a single step, etc.

What pins to connect the thermistor too?


from your link:

The circuit is basically: Vcc — 10K resistor — P1.2 — Thermistor — 0V


the launchpad board is labelled. vcc is + voltage, like a red wire from a battery. 0v is also known as gnd, short for ground, or like the black wire from a battery. p1.2 is a pin on the chip. you could connect to any p#.# labelled pin on the chip so long as your code refers to it - they are programmable. a thermistor is a resistor that changes its resistance with temperature. so the resistor would go from vcc to p1.2 and the thermistor from p1.2 (where it meets the resistor) to gnd forming a resistive divider: http://en.wikipedia....sistive_divider with its v out connecting to p1.2 where it can be detected and measured by your code.

how to upload the code files onto the chip?


via software on your computer connected to the launchpad with a usb cable. code composer studio from ti is recommended but there are other options. i'm finding ccs a little frustrating but sticking with it for now in the hope of learning the code a little better. i understand a lot of the concepts but not the code and am not finding ccs as intuitive as i feel it could be.
*edit* also: support - some community projects are likely to be abandoned due to the developers having other interests and a life to live, etc, so css is probably worth persevering with - perhaps more newbie feedback would help with its development but i've yet to engage.

someone recently posted a link to this book:
http://myweb.wit.edu...ller Basics.pdf
see page 375 for thermistor connection but its worth reading all of it. more reading here:
http://www.43oh.com/...c.php?f=8&t=449

*edit* here's another couple of noob friendly msp430 resources i recently stumbled upon and found useful:
http://www.swarthmor...oToMSP430_C.pdf
http://www.swarthmor...t/MSP430QS.html
*edit*

you should probably read up on some basic electronics tutorials too, there are plenty of resources on the net - google is your friend. work your way through a book googling words, phrases and concepts that you don't yet understand as you go.
hope that helps - have fun!
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ohm's where the art is

#3 larsie

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Posted 15 September 2012 - 08:12 PM

And on the msp430, the pins can have different functions. So the code sets this pin to act as an analog input. The analog input becomes a number from 0 to 1024 (depends on the resolution of the analog to digital concerter). You can read the same voltage with a normal multimeter. The code then uses an algorithm to translate that number on that pin to the actual temperature. The algorithm is borrowed from reprap code.

Energia can be a good tool to start playing with, but you can't run that code from the post directly. It will let you read analog values with less code than proper C.
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