1-wire client and DHT22

Projects General Guidance
1

Hi all,

I have a project to build a custom 1-wire probe in order to expose DHT22 data.
In order to save me some time :

  • which is the best 1-wire client library on the Arduino
  • which would be the cheapest Arduino model that can carry both 1-wire and DHT22 library ? The smallest, the better :slight_smile:

Thanks

Laurent

2

The smallest would be the Beetle (super tiny) or the Pro Micro, both have the ATmega328p processor. Pro Micro is probably the cheapest, clones are selling for just over USD 1 a piece on Taobao.

Even smaller would be the 8-pin ATtiny85, should be able to handle that just fine. Not sure about the smallest packages; more modern ATtinys go as small as 3x3 or 4x4 mm QFN packages (and have up to 12 I/O available). Can't get much if any smaller than that.

There are several one-wire protocols out there. The DHT22 is one example. The DS18B20 is another.

3

PLease note that the DHT22 has a proprietary protocol. It cannot be compared to 1 wire.

Check for DHT22 - Arduino/libraries/DHTNEW at master · RobTillaart/Arduino · GitHub

4

robtillaart:
PLease note that the DHT22 has a proprietary protocol. It cannot be compared to 1 wire.

Yes, I know :slight_smile:

Probably I wasn't so clear in my request : my goal is to create a custom 1-wire Slave to expose DHT22 data on my 1-wire smart home network.
Then I'll modify OWFS to handle this new kind of probe.

Rgds

Laurent

5

DHT22 is not addressable, so you can only have 1 DHT22 on a one wire network and nothing else.

6

destroyedlolo:
Yes, I know :slight_smile:

Probably I wasn't so clear in my request : my goal is to create a custom 1-wire Slave to expose DHT22 data on my 1-wire smart home network.
Then I'll modify OWFS to handle this new kind of probe.

Rgds

Laurent

If you have a one wire slave software you can connect multiple DHT22 to it.
The way to do this is to have a separate pin for every DHT22.

If the slave can mimic multiple addresses , or you see the collection as one device with e.g. 5 temperatures, than all parts come together.

7
  • 1 DHT22 per Ardunio
  • individual address per Arduino

So all, in all, they will act as a 18B20 but will provide humidity as well.

8

which is the best 1-wire client slave library on the Arduino

This.

9

Best arduino for that is probably pro mini (or attiny solution of some sort)

Pro micro uses 32u4, not 328p and costs more. Don't usr it if you don't need native usb

10

Oups, I didn't see that someone has replied.
Thanks all.

I'm starting some test with some ATTiny85 ... and will let you know.

Bye