I try to monitor 4 rooms with air conditioning. I bought for this project 4 DHT11 “bricks” (which have a 10K pull up resistor already). The cables to the rooms are less than 8 meters each so this should not be a problem in my opinion. All 4 DHT11 are connected to my Raspberry Pi and they are connected to the 5V, not the 3.3V. If I connect the signal of the DHT11 directly to my Raspberry Pi all readings are wrong! One is correct but the three others give me values like 15C and a humidity of 150. (should be around 30C). In order to solve this I installed an extra 10K parallel at the Raspberry Pi IO-port over the existing 10K (which is already at the “brick”) so the pull-up resistor will go from 10k => 5k, but even after that still not working properly, sometimes values are correct, sometime wrong. If I connect the DHT11 sensor directly to my Arduino Uno with a breadboard (so not using a cable), no problem - all values are correct so the DHT11 are working properly.
I run Raspbian with the latest kernel: Linux 3.18.13+ with all updates, also all Pimatic updates.
What do I do wrong, I run out of options…
