1 wire temp sensors

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Guys,

I am working on the final stage of my motorbike repair, and as a self-respecting freak I added a DS1820 to the pulse-generators, in order to measure oil temperature. With an AVR of course.
But I am a bit puzzled, .... trying to sort out the difference between a DS1820 and a DS18B20. The datasheets have different *looks*, but content-wise I cannot find where these two are really different.

Clarification is appreciated :)

Nard

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Yes they are. DS18S20 and DS18B20. Not only resolution, but also the command set.

I typed from memory. I have not looked recently.

David.

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If you google for "DS1820 versus DS18B20" you will these:
http://www.maxim-ic.com/app-note...
http://www.picaxeforum.co.uk/sho...

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Nard,

I remember it as ... DS18BETTER20

Cheers,

Ross

Ross McKenzie, Melbourne Australia

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Great guys, thanks.

The silicone compound has almost hardened and now the built-in sensor on a 80cm coax (100pF) refuses to work. A fresh DS1820 in the breadboard works fine. Is that 100pF of the coax the killing factor ?? It reads 85 degr C all the time.

< some more testing .... >

O crap, the fresh DS1820 in the breadboard works fine, even with 220pF in parallel. Apparently I damaged the glued-in one when soldering it to the coax. Not a good day. :(

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The 85C is a software problem.
Does danni's one-wire library give you that?

I agree that the device is not really suitable for oil temperature.

David.

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George, I am aware that the DS1820 is an obsolete part: but I had 4 in stock, and accuracy is not that important for this purpose. My bike (Honda Shadow VT500C) is a fluid-cooled engine, with a fan behind the radiator that kicks in @ 80 degr C. So I am lucky.
Automotive is a hostile environment, I know. Worked in automotive for several years.

Attached a picture of the poor bugger. And those ugly looking black creatures are the new pulse generators. Completely covered in 250 degr resistant silicone mastique. I need my own extruder for plastics ! :)

DS1820 out, good old NTC in.

cheers

Nard

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david.prentice wrote:
The 85C is a software problem.
Does danni's one-wire library give you that?

I agree that the device is not really suitable for oil temperature.

David.

I adapted a Bascom application note to test the DS1820. As I wrote earlier: a fresh DS1820 on the breadboard works, pulling it out and plugging-in the wires of the glued-in one gives the 85 degr C.

Since I cut it off there is no way back. An NTC will now do the job instead.

Thank you all guys, for your help !

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Quote:
Nard, your engine is water-cooled!
Hehe, .... then beer is water :?:

Not a few centigrades, George. We had a very cold weather a few weeks ago (minus 15, all is relative, of course) and I would not have let my old girl (26 years) in the shed without proper cooling fluid. Protection until minus 37 degr C.
About oil: I agree. And nothing but the best for my old girl. No el cheapo oil from the supermarket. She has her standards .....

The pulse generators did fine for 26 years. Not bad, IMO. But your theory sounds valid: when I chopped the plastic it was all very oily inside. The one that still worked was much harder to crack than the defective one. The magnet of the working one broke in two because of the violence needed to free the metal innerworks. *That* was a good day: I didn't expect I could re-use the metal. Me lucky-dog.

Time will tell if I did it right. There was no alternative: spareparts for my classic is a pain. My backup-plan was to mount hall-sensors and generate a pulse-generator-like signal ... with an AVR, of course. I am quite pleased that I could stick to the original concept. Although I did the trick with the Hall-sensors and mocking-up a pulse-generator-signal in my automotive days.

There is only one AVR on board now: to do the indicators. These are led-based now; the original indicators broke at the flex-joint. No replacement at a reasonable price. Ripp-offs plenty. And the transition to leds was a logical step.

Sensors are now being baked for the last time. When done I will do a calibration of the built-in NTC, for later reference. When the second AVR comes in. With a nice LCD. And *resistive* touchscreen. Guess why ;)

Cheers

Nard

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Nice job ! Intel micro ?

A GIF is worth a thousend words   They are called Rosa, Sylvia, Tricia, and Ulyana. You can find them https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

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Whoooo, ...... the brand that shall not be named ?!

Just kidding. A PIC ?

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Done :)

See https://www.avrfreaks.net/index.p... to see me being happy and, of course, a scope snapshot.

A GIF is worth a thousend words   They are called Rosa, Sylvia, Tricia, and Ulyana. You can find them https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips