experience on combined Temp/Humedity sensor based on DHT11

[walteroa]

Hi All,
I'm wondering if anybody has tried to use this combined sensor DHT11 instead of using this couple (HIH4000+DS18B20)..?? 
Thx in advance
alter

 

 

[CAI_Support]

DHT11 has different handshaking signals from DS18B20 or HIH4000.  DHT11 has less accuracy than DS18B20 and HIH4000.
For example, DS18B20 can achieve 0.2 degree accuracy, DHT11 has 2 degree accuracy.

 

[CAI_Support]

DS18B20 is also pretty cheap, look this item on eBay:
http://www.ebay.com/itm/261191127246
or
http://www.ebay.com/itm/200721558303

 

[Automate]

The accuracy of the DS18B20 is +- 0.5 C from -10 to 85 C and +- 2 C from -55 to 125 C
 
Data sheet here http://datasheets.maximintegrated.com/en/ds/DS18B20.pdf

 

[CAI_Support]

True, 0.5C accuracy is minimum. The datasheet also stated:
 
The resolution of the temperature sensor is user-configurable to 9, 10, 11, or 12 bits, corresponding to increments of 0.5°C, 0.25°C, 0.125°C, and 0.0625°C, respectively. The default resolution at power-up is 12-bit.
 
That 12bit is what we use, however, we round that to 0.1C in our data format. In F, that is about max 0.2F.

 

[walteroa]

Thx folks.. my question was about handshake.. 1-wire vs the one who is managed by DHT11.. (because I already have one).. Agree ds1820 is cheap enought but in the other hand HIH4000 is still expensive.. thx guys anyway.

 

[CAI_Support]

True, Honeywell sensor is expensive, about $11 or so a piece for a little chip.  WebControl does not have bus to support DHT11.  Maybe we could release something to support that instead of DS18B20 and HIH4000.  How many DHT11 can run on the same bus?

 

[walteroa]

No idea how many.. but looks a little challinging.. take a look at embedded-lab.com/blog/?p=4333

 

[walteroa]

more info about DHT datasheet at http://www.aosong.com/asp_bin/Products/en/DHT11.pdf
 
and some other blog: http://www.candrian.gr/index.php/dht-11-one-wire-bus/
 
I hope this can contribute to enhace Webcontrol..

 

[CAI_Support]

Thanks for the information. Since its communication only send data, no device ID, I think that is probably one bus per device. DS18B20 allows a lot more on the same bus, since each device has its unique ID.