hi! i got an "DHT22" on pcb. like this: DHT22 on PCB
I get it to work and show temp and humid, but the temp atleast is wrong with a couple of degrees :S can someone help with that?
DHT22 sensors are pretty unprecise. So if you want to keep the DHT22 sensor you could write a correction-table as an array.
This correction-array will need RAM. So it is important to know what exact type of microcontroller you are using.
If you want a more precise temperature and precise humdity use a SHT-sensor instead of the DHT22.
If you want more precision use a SHT40
very good temperature precision of 0,1 °C can be achieved with a TMP117
0.5°C degree precision can be achieved with DS18B20 sensors.
best regards Stefan
Too high, too low, high and low?
Using a DHT and a true thermometer, record these temperatures after 10 minutes
- in a freezer
- in a refrigerator
- in a room
- in an oven at 50c for 10 minutes (datasheet says it can work up to 80c)
The error percent at each measurement is: ((measured - true) / true) * 100.
If the error percent is the same at each temperature, use that value for every DHT reading.
If the error percent graph at each "true" temperature is not flat, draw a "best fit" line, then use the point-slope equation of that line (y = mx + b) on every DHT reading.
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