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dentex
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ds18b20 temperature probe's VDD

Sat Jul 09, 2016 8:00 am

Hello!
I was wondering if I could use the Pi's 5V rail to power the DS18b20 temperature probe instead of the 3v3.

According to the datasheet
http://datasheets.maximintegrated.com/en/ds/DS18B20.pdf
this seems to be ok, but I was just looking for a confirmation:)

Thanks in advance.
Last edited by dentex on Sat Jul 09, 2016 1:03 pm, edited 1 time in total.
One of my projects with the Raspberry Pi:
--------------------------------------------------------
(Raspberry) Pi Aquarium Controller: https://github.com/dentex/piac

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B.Goode
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Re: ds18b20 temperature probe VDD

Sat Jul 09, 2016 8:28 am

If you power the probe with 5v, won't it return 5v on its signal line? And won't that cause damage to the GPIO pin on the RPi that you are using for the 1-wire bus? (Unless you anticipate this and use a voltage divider.)

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rpdom
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Re: ds18b20 temperature probe VDD

Sat Jul 09, 2016 9:44 am

B.Goode wrote:If you power the probe with 5v, won't it return 5v on its signal line? And won't that cause damage to the GPIO pin on the RPi that you are using for the 1-wire bus? (Unless you anticipate this and use a voltage divider.)
I believe the data line is open-collector, hence the need for a pull-up resistor. As long as the pull-up is connected to 3V3 it shouldn't matter what the voltage on the V+ pin is.

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B.Goode
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Re: ds18b20 temperature probe VDD

Sat Jul 09, 2016 9:58 am

Happy to be corrected if it is still 3.3v safe.

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dentex
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Re: ds18b20 temperature probe VDD

Sat Jul 09, 2016 11:50 am

Many thanks guys. Understood. :)
One of my projects with the Raspberry Pi:
--------------------------------------------------------
(Raspberry) Pi Aquarium Controller: https://github.com/dentex/piac

User avatar
dentex
Posts: 180
Joined: Sun May 20, 2012 7:58 am
Location: Italy
Contact: Website

Re: ds18b20 temperature probe VDD

Sat Jul 09, 2016 12:45 pm

And searching the forum more thoroughly, I found the same answer:
viewtopic.php?f=37&t=30359

Thanks again.
One of my projects with the Raspberry Pi:
--------------------------------------------------------
(Raspberry) Pi Aquarium Controller: https://github.com/dentex/piac

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