warhammer73
Posts: 4
Joined: Fri Mar 03, 2017 8:43 am

DHT22 - one pullup for more then one DHT22?

Wed Apr 26, 2017 11:36 am

Hello,

I will use 3 DHT22 with my rasperry. For testing I'm using one 10k pullup resistor for each DHT22.
For the final implementation: Can I use just one resistor for all 3 DHT22?


Thanks!

PhilE
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
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Location: Cambridge

Re: DHT22 - one pullup for more then one DHT22?

Wed Apr 26, 2017 12:20 pm

Moved where it is more likely to be answered.

PhilE
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 2542
Joined: Mon Sep 29, 2014 1:07 pm
Location: Cambridge

Re: DHT22 - one pullup for more then one DHT22?

Wed Apr 26, 2017 12:24 pm

BTW, I've never seen or used a DHT22 but from what I've just googled it uses a simpler protocol than Onewire (there's no concept of an address) and requires a dedicated line for each device, and you can't pull up multiple wires with a single resistor without shorting them together.

warhammer73
Posts: 4
Joined: Fri Mar 03, 2017 8:43 am

Re: DHT22 - one pullup for more then one DHT22?

Wed Apr 26, 2017 12:39 pm

You are right.
With my ideal I will connect all data Pins together...

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joan
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Location: UK

Re: DHT22 - one pullup for more then one DHT22?

Wed Apr 26, 2017 1:19 pm

Each DHT22 needs a separate GPIO and a separate resistor.


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