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added support for DS18S20 (ass opposed to DS18B20) for cold junction #94

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merged 1 commit into from
Feb 4, 2018

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gravestench
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Hi there,

I couldn't find any cheap DS18B20 one-wire sensors, so I tried a drop-in replacement DS18S20. Initially, it didn't work, but after looking in the code I could see that it just needed another family code defined in onewire.c and another if-else clause added.

I also saw that someone asked about this here.

I can confirm that this is known working :)

@GitLang
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GitLang commented Jul 26, 2016

It will only operate at 9 bits though, where the 'B' will operate at 9, 10, 11 or a2 bit. Is 9 bits accurate enough?. Where did you look for DS18B20's ?. They are every where for 1 dollar - ebay, amazon, etc.

@gravestench
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gravestench commented Jul 26, 2016

Hi, thank you for the reply!

The DS18B20 variants were all $2 to $3 (and still are), and the plain "DS18B20" sensors were not stocked by my preferred vendors (Mouser & Newark). I figured they would be more expensive on ebay, so I just looked for an equivalent. This situation was caused by my compulsive, frugal, and impatient behavior, I understand... but all I wanted was to get this mod working with the sensor I bought, so I did! After looking around I saw that at least one person had tried using this sensor, so I figured I would push my change.

9 bit resolution gives you roughly 0.5C granularity, I don't see what that should be a problem. I have yet to actually reflow my boards, but am fairly confident things should run smoothly. Should I be worried?

Thanks again for the reply.

@xnk xnk merged commit 4b0e930 into UnifiedEngineering:master Feb 4, 2018
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3 participants