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.
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Pin Identification and Configuration No: Though not discussed in detail on this page, the effect of using the protective cover on the response speed has been investigated elsewhere. It would therefore seem that any particular device is datashet guaranteed to meet these specifications. Many thanks to Nava Whiteford who has sent me some scanning electron micrographs of what is inside the BME Plots showing the deviation of humidity values from the known reference value.
This run confirms my previous experiments with this device. For this test I am running one device each, with and without.
If you are trying to interface DHT22 with Arduino Uno then there are ready made libraries for it which will give you a quick start. The other six are new and this is their first test. Plotted for comparison are values taken from the published literature. The curves in Figure 4 are effectively cross sections through these surfaces.
For this reason I plot both the raw data where the AM23xx devices can all be seen to lag by one reading and also a version where that offset has been artifically removed. Drivers for other sensors were based on datasheets and sample code published by their respective manufacturers.
Figure 11 shows an apparent scatter but replotting temperature errors as a function of humidity Figure 12 shows a tight correlation with very little dispersion. They seem to under-promise and over-deliver, so a priori I am not expecting problems outside the specified range.
This, the Si and the SHT71 showed comparable errors overall. All data collected, irrespective of temperature, are shown as blue dots.
DHT22 Sensor Pinout, Specs, Equivalents, Circuit & Datasheet
The word is derived from ancient greek for ‘lagging behind’. The humidity axis has been set to the same range in all three plots in order to fairly represent the relative gradients of the lines. Almost vaguely related and possibly of interest is monitoring radon in the house.
There is some suggestion from the manufacturer’s web site that this might already be discontinued and replaced by AM The DHT22 is a commonly used Temperature and humidity sensor. However, for all devices except the Si and AM the effect is small and the width of the envelope is not larger than the scatter of data points already observed.
The one-wire serial of the AM is retained making this a simple drop-in replacement. If the device caps output at 0— it makes it difficult to apply your own re-calibration near those limits. My HTU21D exhibited good thermal stability and extremely low hysteresis. For example, with the highly responsive HTU21D, I often see spikes and wobbles in the readings as I move around the room, stiring the air. Over two years, three of the original six devices have failed.
The left panel shows the actual results you would datasbeet when using the device and the right panel more directly compares the intrinsic physical response of the sensor elements. For most sensors the traces followed on rising and falling humidity are reasonably close together, showing little hysteresis bias.
Compare DHT22, AM, AM, AM, SHT71, HTU21D, Si, BME
Oddly they appear to work reliably above and below that range. They have remained fairly consistent over the six months between the two experiements. My current hypothesis is that the sensor element is contaminated and I have some experiments ongoing March to investigate that. The sensor comes with a dedicated NTC to measure temperature and an 8-bit microcontroller to output the values of temperature and humidity as serial data.
The sensor is also factory calibrated and hence easy to interface with other microcontrollers.
In contrast, the AM device G shows little error as a function of humidity Figure 12 but has the largest error as a function of temperature Figure Serial data Temperature Range: