emonTH - subsituting DHT22 for DHT44

Submitted by andy_l on Mon, 19/01/2015 - 00:16

Hi there,

Has anyone used the DHT44 (now RHT05) temperature/humidity sensor with the emonTH? It's supposed to be fully compatible with the DHT22 and looks ideal for remote mounting away from the emonTH node.

www.humiditycn.com/cp20.html

Only problem is getting hold of one - only found a supplier in Switzerland and it works out to 20GBP per unit...

Cheers,

Andy

Re: emonTH - subsituting DHT22 for DHT44

Submitted by Robert Wall on Tue, 10/02/2015 - 15:02.

Presumably not. Cost?

Re: emonTH - subsituting DHT22 for DHT44

Submitted by andy_l on Sat, 28/02/2015 - 23:52.

Yep more than likely. I also overlooked the shipping - makes it a whopping 40GBP... Oh well.

Re: emonTH - subsituting DHT22 for DHT44

Submitted by chaveiro on Mon, 02/03/2015 - 18:55.

I've tight interrupt timing requirements and DHT22 polled protocol was not and option.

I've ordered (still waiting) the new HTU21D that looks promissing and can use hardware i2c bus so other cpu task can remain active instead of pooling pins to know the data.

Re: emonTH - subsituting DHT22 for DHT44

Submitted by TimSmall on Fri, 06/03/2015 - 15:47.

Did you look at the Sensirion SHT21, which is also i2c? I've seen them on breakout boards from time to time (via eBay and aliexpress etc.).

Re: emonTH - subsituting DHT22 for DHT44

Submitted by chaveiro on Fri, 06/03/2015 - 15:59.

Yes i've looked at SHT21 that is pin compatible with HTU21D and can be found with a nice external casing.
I order the last because it was cheaper.
There are many options with i2c.

Re: emonTH - subsituting DHT22 for DHT44

Submitted by TimSmall on Fri, 06/03/2015 - 16:22.

OK. FWIW, Sensirion SHT21 (SMT device) without casing is around UKP £3, and I've bought them on breakouts for around £5.

Whilst I don't have any long-term accuracy or stability data for the SHT21, other Sensirion sensors seem to outperform cheaper devices from other manufacturers.

Re: emonTH - subsituting DHT22 for DHT44

Submitted by TimSmall on Thu, 30/04/2015 - 10:26.

I have the SHT21 working now - detail here: http://openenergymonitor.org/emon/node/10199

Re: emonTH - subsituting DHT22 for DHT44

Submitted by davekramkowski on Thu, 10/09/2015 - 04:38.

This has obviously been out there for a minute, but I have a DHT44. I had originally acquired it for another project that has since been binned, but I just recieved my EmonTH's and decided to plug it up to one and it appears to read proper data when plugged into the DHT22 port right out of the gate with no modifications.

[Duplicate post deleted - Moderator (RW)]

Re: emonTH - subsituting DHT22 for DHT44

Submitted by mpruessmeier on Wed, 23/09/2015 - 15:18.

That sounds great ;-)

The DHT44 is a RHT05 i found out. It is produced by MaxDetect Technology Co., Ltd.
You will find a description here: http://www.humiditycn.com/pic/20135318415585088.pdf

I'll write a mail to Thomas Liu to ask about a bulk price.

When they are working we will need round 20 Pcs of it.
Is someone else interested in an order too?

Greetings Marc

Re: emonTH - subsituting DHT22 for DHT44

Submitted by andy_l on Fri, 25/09/2015 - 20:56.

Hi Marc,

I would definitely be interested in buying one or two DHT44 if the price is right :)

Cheers,

Andy

Re: emonTH - subsituting DHT22 for DHT44

Submitted by mpruessmeier on Sat, 17/10/2015 - 11:23.

I tried to catch someone at MaxDetect Technology Co., Ltd. but nobody answered yet.

Re: emonTH - subsituting DHT22 for DHT44

Submitted by andy_l on Fri, 01/01/2016 - 20:24.

There are suppliers carrying the DHT44 on eBay now - I managed to pick one up from China for £13 inc shipping. A search for AM2305 should turn up results.

Cheers,

Andy

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