Digital Receipt System for Card Transactions

Overview

The objective of the digital receipt system is to provide a credit card or ATM purchase where the transaction information is automatically packaged and logged in a database by sending via webserver.

Explanation

This prototype was built with custom PCB along with the ATmega644 microcontroller, RS232 connector, and MAX233ACPP chip. Seven pins of the MCU is being occupied by the LCD display which includes the standard HD44780 controller. The cardholder’s name is stored only on track 1 on a credit card magnetic stripe. The data from a magnetic stripe can be read by the card reader which has its own controller then the information is sent over the serial interface which occupies 2 pins on the MCU.

An Ethernet module is required to communicate suing a different interface because the card reader occupied the RS232 UART on the microcontroller. The SPI type was ideal for the Ethernet module because it only requires 4 pins on the MCU since some Ethernet modules that support an 8-bit interface are limited to the number of available pins. The buttons of the 3x4 keypad have 0-9 digits which is matrix encoded and will only occupy 7 pins.