RFID Interfacing with Arduino
In this tutorial we are going to design a system to read the ID of RFID cards. RFID stands for Radio Frequency Identification. Each card has a unique ID embedded in it. These systems have many applications, like in offices, shopping malls and in many other places where only the person with authorization card is allowed to enter in the room. RFID is used in shopping malls to stop a theft from happening, here the product will be tagged with RFID chip and when a person leaves a building with the RFID chip an alarm is raised automatically and so the theft is stopped. The RFID tag is designed as small as grain of sand. The RFID authentication systems are easy to design and are cheap in cost. Some schools and colleges nowadays use RFID as attendance register.
Hardware: ARDUINO UNO, power supply (5v), 100uF capacitor , buttons (two pieces), 1KΩ resistor (two pieces), EM-18(RFID reader module), LED, JHD_162ALCD (16*2LCD).
Software: arduino IDE (Arduino nightly).
Circuit Diagram and Explanation
In 16×2 LCD there are 16 pins over all if there is a back light, if there is no back light there will be 14 pins. One can power or leave the back light pins. Now in the 14 pins there are 8 data pins (7-14 or D0-D7), 2 power supply pins (1&2 or VSS&VDD or GND&+5v), 3rd pin for contrast control (VEE-controls how thick the characters should be shown) and 3 control pins (RS&RW&E).
In the circuit, you can observe that I only took two control pins as his give the flexibility of better understanding. The contrast bit and READ/WRITE are not often used so they can be shorted to ground. This puts LCD in highest contrast and read mode. We just need to control ENABLE and RS pins to send characters and data accordingly.
The connections which are done for LCD are given below:
PIN1 or VSS to ground
PIN2 or VDD or VCC to +5v power
PIN3 or VEE to ground (gives maximum contrast best for a beginner)
PIN4 or RS (Register Selection) to PIN8 of ARDUINO UNO
PIN5 or RW (Read/Write) to ground (puts LCD in read mode eases the communication for user)
PIN6 or E (Enable) to PIN9 of ARDUINO UNO
PIN11 or D4 to PIN10 of ARDUINO UNO
PIN12 or D5 to PIN11 of ARDUINO UNO
PIN13 or D6 to PIN12 of ARDUINO UNO
PIN14 or D7 to PIN13 of ARDUINO UNO
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