Hi, I have 2 DHT22 sensors which works fine when I have them connected on short prototyping leads. I need them about 6m from the RPI and am using ethernet cable to run the distance. I now get very inconsistent readings but have read that the DHT22 can be run up to 30m away. Anybody have similar issues? See screenshot below of the readings I am getting.
Can’t you connect it to an ESP with a shorter distance instead?
If you have any mains power in the greenhouse then you could connect the temperature sensors to an ESP instead.
I think, it would not work. In your place, I will use 485 differential drivers (very cheap) and serious filltering of dc supply at the end of cable.
See:
https://www.raspberrypi.org/forums/viewtopic.php?t=195959
“The maximum cable length can be up to 30 meters / 98 feet if you use 5 V power and 1 meter / 3.3 feet if you use 3.3 V power (see Datasheet).”
Yeah that’s not right. Any more than 10cm is problematic.
yes I think it is incorrect, I now tested it with a 2m cable and that works fine, but seems anything longer is a problem.
How long did you test it for?
It may be more reliable but you will probably still get the occasional incorrect reading.
I tested it for about 3 days on the 2m cable and was perfect all the time. Tried changing it to 4m and now get the sporadic readings of before.
sorry Igor, I am a novice, 485 differential drivers is Greek to me…
Well, unfrtunatelly there is no ‘instant’ knoweledge possible. Try googling about differential drivers.
Complete noob here, but i had an odd issue with my dht22 when I set it up on my first project. My yaml all worked and compiled fine, sensor output on the serial interface would read the correct values on the first boot after the flash.
Once shut down and rebooted it would read waaaaay cold no matter what. Reflash would work fine on first boot, reboot, sensor reading off again.
Turns out i neglected to specify the dht22 device type in the yaml. Once I set it to dht22 it would work fine after reboots.