DHT22 extreme values

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First of all thank you for this awesome piece of software.
I Love it.

I setup pimatic a month ago and had 2 DHT22 sensors directly attached to the pi through GPIO.
Now i want to add some more and tried to connect then with the Arduino mini.
The problem now:
At least 4 times a day i got extreme values like -3000°C or +200°C.
Also the log is full of Checksum Errors (the cable of the DHT22 is about 20cm long and I had the same Kabel attached to an CAT5.e cabel before, when it was directly connected to the PI).
I tried to set the measuring time to higher values like every 20sec or 1 minute but it didn´t help.
Is it possible to set max value so my statistic graph doesn´t get corrupted?
And how do I get rid of the Checksum Error?

Or is it possible to connect more than one DHT22 sensors on one data GPIO pin on the PI?

thank you for your help

its not possible to use more then one dht on a gpio. did you use a 10k pullup resistor between the 3v3 and data line (gpio wire)?

Okay so I have to use the Arduino nano.

Yes there is an 10k resister between the 3v3 and the data line.
It worked as long as I have used the GPIO pins directly. My second DHT22 connected directly to the GPIO works like charme.
Just the connectedt DHT22 on the Arduino nano producess this extreme values.

friendly bump

Here now and then some extreme values as well, and loads of checksum errors popping up the last weeks. I have a DHT22 connected directly to an Arduino nano running homeduino. A 433MHz receiver and transmitter are connected as well. The DHT has a 4k7 or 10k pullup on the data line.

@dtjftj-tjrtjrtrtj Using pimatic-dht-sensors you can connect two DHT sensors to the Raspi through GPIO. I have just tested it with a DHT22 and DHT11. Values are read flawlessly.

Hi, i get checksum errors, too.

I have 2 dht sensors connected with The arduino, the one dht22 has a length of 40cm,the other has ca 3meters.
The dht22 from 40cm length shows checksum error. Can somebody help?

I have per dht sensor an 10k resistor erstand between power and data.

Greets Dodo

The DHTLib used as part of homeduino Arduino sketch is pretty outdated.
I’ll get the current version and will integrate that for testing.

Okay thx, thats nice @mwittig

@mwittig do you have news?

Greets

@Dodo88 I have updated the code, but I haven’t tested it yet. I’ll keep you posted

@mwittig did you find time to test?

@Dodo88 I have pushed the update to the dhtlib-update branch which compiles fine for me with the Arduino IDE. I haven’t tested the Linux build tool chain yet. Please let me know what you’re using, i.e. Arduino IDE or make. I’ll then give you further instructions as required.

@mwittig Mh… I flash the nano with this tutorial

https://forum.pimatic.org/topic/202/4-homeduino-433-mhz-sending-receiving-and-even-more

Can you read there what i need?

@Dodo88 That’s great. The only difference is in step 2) of Flashing process where the homeduino repo is cloned. You need to do this as follows:

 git clone -b dhtlib-update https://github.com/pimatic/homeduino.git --recursive

@mwittig
Okay, can i do this without clear an directory?