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General topics about hardware.
DHT22 wrong readings
7 years 10 months ago #3621
by pocasolta
DHT22 wrong readings was created by pocasolta
hello everyone,
I am experiencing wrong temperature and humidity readings when using a D1 mini (ESP8266) to read a DHT22 sensor.
Temperature is 2 to 4 degrees higher than real and humidity is 15-30% lower.
The sensor is placed away from the ESP8266 so no heat from the processor distorts readings.
I have tried different units of DHT22 and all give me the same result.
I also tried an arduino nano with these sensors and with the nano it works ok. with the same DHT22 units, readings are good.
I used the same libraries for DHT readings with nano and D1 so the only thing different is the device (D1 mini vs arduino nano). Do you have an explanation of what could be happening here?
Thank you very much in advance!
I am experiencing wrong temperature and humidity readings when using a D1 mini (ESP8266) to read a DHT22 sensor.
Temperature is 2 to 4 degrees higher than real and humidity is 15-30% lower.
The sensor is placed away from the ESP8266 so no heat from the processor distorts readings.
I have tried different units of DHT22 and all give me the same result.
I also tried an arduino nano with these sensors and with the nano it works ok. with the same DHT22 units, readings are good.
I used the same libraries for DHT readings with nano and D1 so the only thing different is the device (D1 mini vs arduino nano). Do you have an explanation of what could be happening here?
Thank you very much in advance!
The following user(s) said Thank You: sharonlei
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7 years 10 months ago #3624
by EasyIoT
If temperature readings are off then also humidity readings are off, because sensor compensate humidity readings with temperature readings.
I'm using DHT22 for thermostat and if DHT22 is mounted on plastic case temperature is about 1 degree higher compared to readings if sensor is in the air.
Replied by EasyIoT on topic DHT22 wrong readings
pocasolta wrote: hello everyone,
I am experiencing wrong temperature and humidity readings when using a D1 mini (ESP8266) to read a DHT22 sensor.
Temperature is 2 to 4 degrees higher than real and humidity is 15-30% lower.
The sensor is placed away from the ESP8266 so no heat from the processor distorts readings.
I have tried different units of DHT22 and all give me the same result.
I also tried an arduino nano with these sensors and with the nano it works ok. with the same DHT22 units, readings are good.
I used the same libraries for DHT readings with nano and D1 so the only thing different is the device (D1 mini vs arduino nano). Do you have an explanation of what could be happening here?
Thank you very much in advance!
If temperature readings are off then also humidity readings are off, because sensor compensate humidity readings with temperature readings.
I'm using DHT22 for thermostat and if DHT22 is mounted on plastic case temperature is about 1 degree higher compared to readings if sensor is in the air.
The following user(s) said Thank You: sharonlei
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7 years 10 months ago #3630
by pocasolta
Replied by pocasolta on topic DHT22 wrong readings
good morning,
thanks for the reply. you pointed me at the right direction. I placed 3 DHT22 in a row on a proto board, 2 with arduino nano and 1 with D1 mini. readings were the same.
in conclusion, the wrong values were a result of the DHT22 mount position in the D1 mini. I have a plastic box that contains a D1 mini and a 220-5V transformer. outside of the box I had the DHT22 and I thought there would be no thermal effect from the electronics. I was wrong. One more thing I noticed is that readings are more accurate if I mount the DHT22 in vertical position, with its back free so the air can flow through every angle.
thanks again and happy new year!
thanks for the reply. you pointed me at the right direction. I placed 3 DHT22 in a row on a proto board, 2 with arduino nano and 1 with D1 mini. readings were the same.
in conclusion, the wrong values were a result of the DHT22 mount position in the D1 mini. I have a plastic box that contains a D1 mini and a 220-5V transformer. outside of the box I had the DHT22 and I thought there would be no thermal effect from the electronics. I was wrong. One more thing I noticed is that readings are more accurate if I mount the DHT22 in vertical position, with its back free so the air can flow through every angle.
thanks again and happy new year!
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