amc2022:grouph:dht22_humidity_temperature_sensor
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Table of Contents
DHT22
| Figure # DHT22 sensing components. Source: https://create.arduino.cc/projecthub/MinukaThesathYapa/dht11-dht22-sensors-temperature-using-arduino-b7a8d6// |
| Figure # DHT22 Humidity sensing component. Source: https://howtomechatronics.com |
Specifications
| Table 2 Table describing DHT-22 Specifications | |
|---|---|
| Description | Value |
| Operating Voltage | 3.5 to 5.5V |
| Data Protocol | Serial Transmission |
| Operating Temperature | -40 to 80 C |
| Temperature Accuracy | ±0.5°C |
| Humidity Range | 0 to 100 % |
| Humidity Accuracy | ±1% |
| Sampling Rate | 0.5 Hz - Once every 2 sec |
| Humidity Accuracy | ±1% |
| Output Signal | Digital Signal via 1 wire bus |
Schematics
| Figure # DHT22 Schematics. Source: https://components101.com/sensors/dht22-pinout-specs-datasheet// |
Data
Example of how data transmission and the binary system provides information on both Temperature and Humidity.
ESP-32 receives 40 bits from the sensor as follows:
| 16 bits for | RHumidity | 0000 0010 1000 1100 |
|---|---|---|
| + | ||
| 16 bits for | Temperature | 0000 0001 0101 1111 |
| = | ||
| 8 bits | Check-sum | 1110 11101) |
—————————————————————————————————————————————
The conversion from the humidity data is:
| Binary system | > | Decimal System |
|---|---|---|
| 0000 0010 1000 1100 | > | 652 |
\[RH = \frac{\mathrm{652}}{\mathrm{10}} = \mathrm{65.2\;\%}\]
The conversion from the Temperatures data is:
| Binary system | > | Decimal System |
|---|---|---|
| 0000 0001 0101 1111 | > | 351 |
- \[T = \frac{\mathrm{351}}{\mathrm{10}} = \mathrm{35.1°C}\]
If the highest bit of temperature is 1 as in: _1_000 0000 0110 0101, this means that the temperature is negative, therefore T = -10.1 °C2).
amc2022/grouph/dht22_humidity_temperature_sensor.1661351198.txt.gz · Last modified: 2022/08/24 16:26 by gustavo001