High temperature

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#1
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I need to measure High temperatura from 24 to 250 C.
Is there anyone with experience on this issue to share
what kind of sensor to choose and how to read it
with ATMega 8
Thank you

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If you look at the "Ordering information" section of the mega8 (or any AVR) datasheet it shows the various ranges of devices available. For the mega8 I only see "Industrial (-40°C to 85°C)" as the widest temperature range.

You may want to look at the "Automative" range of AVRs - they presumably have a wider temperature operating range?

http://www.atmel.com/dyn/product...

I guess the mega88 Automotive is the closest to your mega8 (though, checking the data, it only seems to be rated to 150°C and not 250°C)

Cliff

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I think the OP only wants to measure a temperature up to 250C :) the AVR won't be in that environment I guess :D

There are no semiconductors that can survive those temperatures AFAIK.

250 is quite high a temperature, I guess only a thermocouple is suitable. Unfortunately, interfacing to a thermocouple isn't that easy :(

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Yes.The MCU will be outside of the heater.

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Definitely more caffeine needed over here!! :oops:

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Hi Sergei!
Try to see at the https://www.avrfreaks.net/index.p...
Alexander.

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Both RTD's and TC are suited for this job. I would recommend PT1000 and some external 12 to 16 bit ADC, if you can live with short temp probes.

Guillem.

Guillem.
"Common sense is the least common of the senses" Anonymous.

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As it's for a heater I wonder if 12..16 bits isn't overkill? Depending on the requirement one could design the TC or PT1000 conditioning circuit in such way that 8 or 10 bits suffices, for example 0-5V for 200-240deg. Eight bits would be enough if 1deg/count is accurate enough, that could cover the range between 0-255 deg.