I am new to electronics and microcontrollers and hope this is the right spot on StackExchange. I have been playing around with an Arduino Micro, connecting different sensors and a display and display data.
I just bought a NodeMCU so I can send sensor values to a database using a DHT22. This is the first test, other sensors will follow.
I am using Arduino Studio with the board configuration for this device.
Everything works fine, Wifi, Serial, but I only get bad readings from the sensor.
- I checked 2 DHT22 with my Arduino, they work.
- I read that the Arduino has integrated pull-ups and a ESP8266 might not have them, so I added 4.7k and 10k between data and 3.3V. But I am not entirely sure about this.
- The DHT22 is using 3.3V on the NodeMCU and the Arduino. Not 5V. -> Arduino works.
- I tried different D pins
- I tried removing or adding code lines like dht.begin, pinMode, etc.
- I used the DHTtest example which also gets bad readings.
- I found other projects – Weather monitoring – which showed their wiring. Some of them also did not use a pull-up resistor. I also tried it without.
- Wiring checked multiple times -> I hope I'm not blind right now.
- Measured the resistors i added -> ok
- Measured the voltage between GND and 3.3V -> ok
- I don't have an oscilloscope (yet) so I don't know whats on the data line.
So I am doing something wrong here but I can't figure out what.
Thanks for help. Very much appreciated.
Best Answer
Now had some time after a while to look after this problem.
I accidentally found the reason. At first I thought it was a problem with the breadboard or the jumper cables. But later I found out I unplugged the DHT22 while the controller was powered on.
So it is the same problem as DHT22 needs electrical reset?