Millions of drivers / consumers pass through toll booths paying toll taxes. In the past toll payment system was manually and drivers are using manual system using coin or cash by hand to cross the toll plaza door. The manual process is too slow and drivers have to wait in line for a long time to cross the toll plaza. In standby time the vehicle's oil is also consuming. Nowadays this system of manual toll deduction is changed to automated system. Where the driver does not wait to pay in cash or get a token to cross the toll plaza.
Electronic / automated toll collection systems are very popular these days. They do not require the manual collection and operation of the toll barriers. Vehicle details and payment are stored in an RFID-based system.
This article explains the operation of a simple toll system interconnected with RFID. Each user has a unique identification for their vehicle. When the user scans his tag while passing the square, a certain amount is deducted from his account. A user can also recharge their account in case of insufficient balance. The project was developed using the RFID interface with AT89C51. Relevant messages are also displayed on a 16x2 LCD. The free source code for the program is available in C.
Low-frequency RFID works at a frequency of 125 KHz with radio waves. There is a coil inside the RFID tag and when it is influenced by a magnetic field, it sends a 12-byte identity code to the RFID reader for further processing. (For more details, see the RFID interface with AT89C51).
The RFID tag is used as a unique identity for the account of a particular user. When a vehicle drives through the toll plaza, your driver is asked to scan your RFID tag. If the identity (serial number of the label, ie 12-byte data) is matched with that already stored in the system, the toll amount is deducted from your account. After this, the vehicle has immediate access to the drive through.
This RFID-based toll system also has some additional features. A new user can register it with the system. Also an old user can recharge your account balance. The amount of recharge can be entered into the system through a numeric keypad with AT89C51 interface.
At the beginning, the user is asked to scan their label or ID. The serial code of the tag is identified by the reader module and is sent to AT89C51 for comparison with the stored data. If the ID is matched by the microcontroller, the amount of toll (in this case Rs.10) is deduced from the user's balance and the user gets to drive through the square. Conversely, if the label is not identified, a message ('Wrong ID') will appear on the LCD.
A new user needs to press the '*' switch to register after their identity is RFID-tagged. The new record is then stored by the microcontroller to grant future access. The system also displays 'Error' if the tags do not match during verification. If the user account balance becomes less than Rs.30, a "Low Balance" warning message appears on the LCD. In this case, the user still gains access through the system. The system also asks the controller to reload the account. If the balance falls below Rs.10, 'Insufficient Balance' is indicated on the LCD. The user does not have access until he adds more balance to his account. The amount of recharge is entered using a numeric keypad. You can use the back space when entering the amount by pressing the '*' button on the keyboard. It also has a security feature that if different tags are scanned through the reader at the time of registration, LCD shows 'you have shown different ID'.
When an RFID tag comes in this range, the reader detects it and sends a unique serial tag code. This serial code, consisting of 12 bytes, is received by the microcontroller. This code is the ID for the user and is stored as an array in the microcontroller. If the identifier corresponds with this code stored in the microcontroller array, the user has access through the toll plaza. For more details on the operation and connections of the RFID, consult the RFID interface through serial interruption.