RS, RW and E are tied to P3.6, GND and P3.7 pins. The data line of the LCD are connected to PORT1 Pins of the Microcontroller. A 16 x 2 LCD Display is used to display the count values. This POT can be adjust in order to change the sensitivity of the IR Sensor. Photo Diode and 10KΩ Resistor form a potential divider and the output is given to the non – inverting input of the Operational Amplifier (Op – Amp).Ī 10KΩ POT is connected at the inverting input. Photo Diode is connected in reverse bias with a series resistor of 10KΩ. A 150Ω current limiting resistor is placed in series with the IR LED. The sensor circuit is designed by selecting appropriate value of resistors for both the LED and the Photo Diode. The following image shows the circuit diagram of the Reflective Type IR Sensor Module used in this project. The microcontroller AT89C51 is interfaced to the IR sensor pairs at PORT2 pins – P2.0 and P2.1 respectively. Here, we used the Microcontroller AT89C51, which is an 8051 family microcontroller. The heart of the circuit design lies in designing the Microcontroller interface. Related Post – 2 Digit Up/Down Counter Circuit Working and ApplicationsĬircuit Design of Bidirectional Visitor Counter using 8051 Microcontroller NOTE: A detailed circuit of the IR Sensors (Reflective Type) is mentioned in the Circuit Design section. Here is the list of components and their corresponding values used in this circuit. The transition from low to high, for each sensor pair is detected by the microcontroller and accordingly the count would be increased or decreased.ĭo you know how to Measure Frequency using Frequency Counter? Circuit Diagram of Bidirectional Visitor Counter As a result, the output from the sensor would be a logic HIGH signal. In case of any interruption (due to any person crossing the path), the Photo Diode would start receiving the IR Light and start conducting. The output from the sensor would be a logic LOW signal in this case. In normal operation, IR light from the LED would not fall on the Photo Diode as it is a Reflective type IR Sensor. Output from each sensor is fed to the microcontroller. Two sets of IR sensors consisting of an IR LED and Photo Diode are placed at two ends of the entrance of a room. In this project, we have used an IR LED as the IR Transmitter and a Photo Diode as the IR Receiver. Infrared or simply IR Sensors are devices that work with Infrared Light Source and a Photo Detector like a Photo Diode or a Photo Transistor that act as a Transmitter and Receiver respectively. The circuit works on the principle of IR sensing. Bidirectional Visitor Counter Circuit Principle
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