AM (wired DHT22) temperature-humidity sensor . DHT11 datasheet (https ://)(in chinese, so see the DHT22 datasheet too!). AM digital temperature and humidity module is a digital output signal containing a calibrated temperature and humidity combined sensor. It uses a. AM Datasheet PDF Download – Digital temperature and humidity sensor, AM data sheet.
|Published (Last):||15 February 2011|
|PDF File Size:||13.83 Mb|
|ePub File Size:||13.9 Mb|
|Price:||Free* [*Free Regsitration Required]|
I have nothing much specific to say about this, but I mean that in a good way. The DHT22 Sensor is factory am2032 and outputs serial data and hence it is highly easy to set it up. Finally, if a sensor is to be used to measure humidity under a range of varying temperatures a full bivariate calibration is required.
AM2302 Datasheet PDF
Almost vaguely related and possibly of interest is monitoring radon in the house. I2C is able to address multiple devices on a single bus so long as each has a different address, but since I have multiple samples of the same device I am not able to identify each one uniquely.
A small adjustment to the internal calibration parameters could possibly bring adtasheet device to very nearly match the BME The others all continue uneffected but values were only logged from this sensor when they were sensible. The DHT22 is a commonly used Temperature and humidity datasheeet. Looking at that the bivariate temperature: Data obtained at other temperatures are shown in blue. Deviations from the known reference aj2302 as humidity is systematically cycled from high to low and back to high.
My Si is arguably the poorest xatasheet the three with larger thermal shifts and hysteresis, but given that I am only testing one example of each I cannot say if those are features of the device type or just my particular specimen.
AM F output saturates at The curves in Figure 4 am23002 effectively cross sections through these surfaces. I never found a cause or have any suggestion for why they should fail to produce output in such a narrow range of humidity.
The data scatter is small and the calibration error is linear in both the humidity datasheef temperature directions. Though I designed and integrated the entire experiment, I must acknowledge the many open source projects, both software and hardware, that I used. These two particular BMEs consistently read a higher temperature than all the other devices, though others I have tested subsequently in my investigation of absolute thermometer accuracy have not all followed that pattern.
The sensor is also factory calibrated and hence easy to interface with other microcontrollers. My current hypothesis is that the sensor element is contaminated and I have some experiments ongoing March to investigate that. These plots show the error of each sensor as a function of humidity. It is already included in the errors we have observed.
The word is derived from ancient greek for ‘lagging behind’.
DHT22 Sensor Pinout, Specs, Equivalents, Circuit & Datasheet
In the right hand panel the lag has been arbitrarily removed and the values normalised in order to compare the intrinsic response speed of the sensor elements. At one sample per second values agreed with the polled operating mode where the device was ratasheet to sleep between readings. The DHT11 is clearly a different class of sensor with substantially lower specification and has been dropped from further investigation.
The thin black line is an ensemble fit to them all, weighting all equally.
The dark grey lines are the new hystersis test and create envelope inside which all the readings will fall. Be careful with variable types in your software. The BME delivered easily the best results. Plots showing deviation of each device’s own temperature from the average of all nine, plotted as a function of temperature.
Only for the BME is there a convincing detection of the thermometer being slightly humidity sensitive. They seem to under-promise and over-deliver, so a priori I am not expecting problems outside the specified range. I am not suggesting all BMEs read hot. Throughout the following plots you will notice the data for sensor G are a little more sparse than the others.
This device is a bit different. The large scatter of the blue points however show that the calibration degrades rapidly with varying temperature. The intent had been to include an identical pair of sensors with and without the cover, however when my devices arrived I found the retailer had sent me HTU21s without the cover and Sis with the cover.
As expected, all sensors do show the tendency to read systematically high when the humidity is decreasing and read low when humidity is rising. The am202 obscures the manufacturer’s mark on the left hand device, but reading the internal serial number shows it to be an Si All respond to changes faster than humidity is likely to change naturally, but speed may occaisionally by an issue of interest, for example when measuring a forced flow of air.
At least the values are obviously wrong and an adtasheet function was added to the microcontroller code to simply reject the bad data.