In this article I’m sharing the circuit diagram and programming code for interfacing DHT22 sensor with the PIC16F877A microcontroller IC. When this interfacing will gives the out put values of Realtime temperature and humidity, which will displayed on a 16×2 LCD display.
Circuit Diagram
Working
In this project Interfacing the DHT22 sensor with the PIC16F877A microcontroller will monitoring the temperature and humidity. The DHT22 is a digital sensor capable of providing temperature in degrees Celsius and relative humidity as digital outputs which will displayed on 16×2 LCD display. This project uses the MikroC PRO for PIC to implement the communication between the sensor and the microcontroller, ensuring efficient data capture and display using an LCD module.
The setup begins with initializing the LCD, which is connected to the PORTB of the PIC16F877A. The LCD serves as the output device for the real time display of the environmental readings such as temperature and humidity. The DHT22 sensors data pin is connected to RB1 of the IC and through careful pin manipulation and timing control. The microcontroller can able to send a start signal and then read the 40-bit response from the sensor.
To read data from the sensor, the microcontroller initiates a specific sequence: it sends a low pulse for 25 ms, followed by a brief high pulse, and then switches the data pin to input mode. Upon receiving a response from the sensor, the software processes each bit by checking the duration of the high signal interpreting long pulses as logical ‘1’ and short pulses as ‘0’. These bits are grouped into bytes representing humidity and temperature values, which are then converted into displayable formats.
Finally, the values are shown on the LCD, refreshing every second to provide up-to date information. This project demonstrates an effective way to integrate environmental sensing in microcontroller based applications, such as weather stations, greenhouse monitoring, and smart home devices.
