Comparison between DHT11 (RHT01) and DHT22 (AM2302 – RHT03) sensors
DHT11 VS DHT22 hardware circuit

DHT11 (RHT01) and DHT22 (AM2302 – RHT03) are relative humidity and temperature sensors. These sensors are small, cheap and easy to use. They use only one wire to communicate with mcu.
The following two topic shows how to interface PIC16F877A with DHT11 and DHT22 sensors respectively:
Interfacing DHT11 relative humidity and temperature sensor with PIC16F877A
Interfacing PIC16F877A with DHT22 (AM2302-RHT03) sensor

The following table shows the DHT11 sensor characteristics (from DHT11 datasheet):
DHT11 sensor characteristics

And the following table shows DHT22 (AM2302) technical specification (from AM2302 datasheet):
DHT22 sensor characteristics

The differences between the two sensors are summarized in the following table:

Relative Humidity Operating Range 20 ~ 90% 0 ~ 100%
Relative Humidity Accuracy ±5%RH ±2%RH (Max ±5%RH)
Humidity Resolution 1%RH 0.1%RH
Humidity Repeatability ±1%RH ±1%RH
Humidity Hysteresis ±1%RH ±0.3%RH
Long-term Stability ±1%RH/year ±0.5%RH/year
Temperature Operating Range 0 ~ 50°C -40 ~ 80°C
Temperature Accuracy ±2°C ±0.5°C
Temperature Resolution 1°C 0.1°C

DHT11 and DHT22 interfacing with PIC16F877A microcontroller:
The following circuit schematic shows the comparison between DHT11 and DHT22 sensors connection circuit.
DHT11 VS DHT22 circuit
The microcontroller used to make the comparison between DHT11 and DHT22 is PIC16F877A which runs with crystal oscillator at 8MHz.
The sensor DHT11 as well as DHT22 has 4 pins which are:
Vcc : Positive power supply (+5V)
Data : Sensor data input and output
NC : Not connected terminal
Gnd : Ground (0V).
A pull-up resistor must be added between the data pin of each sensor and VCC (+5V) pin as shown in the circuit schematic (4.7K ~ 10K).
2004 (20×4) LCD display is used to display temperature and humidity results for both sensors.

CCS C code for DHT11 vs DHT22 project:
The comparison between DHT11 and DHT22 (AM2302) sensors full CCS C code is below.

DHT11 VS DHT22 Video:
The following video shows the comparison between the two sensors results.

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