Debit card read/write controller and process

Details Debit card read/write controller and process Debit card read/write controller and process

2000-12-18

2003-06-24

Lee, Michael G. (Department: 2876)

Registers

Coded record sensors

Particular sensor structure

C235S380000, C360S002000

Reexamination Certificate

active

06581831

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to use of a microcontroller to read/write data from/to a plurality of tracks contained on a magnetic stripe value card. More particularly, but not by way of limitation, this invention relates to a system and method for reading and writing data to a magnetic striped card with the use of a microcontroller.
The use of magnetic cards in modern society is well documented. For instance, credit cards are used throughout the worlds. The number of daily transaction using magnetic stripe cards has increased. Business establishments such as supermarkets, stores, gas stations, restaurants, and hotels are providing means to accept credit cards and debit cards as a common way to do business. The applications of magnetic stripe cards in e-commerce, and point of sale terminals drive the technology toward more secure and more economical ways of reading and writing of the magnetic stripe cards.
Recently, a new type of card, sometimes referred to as a smart card, has been used by businesses. Generally, the smart card contains a microprocessor that allows for the reading and writing of data as the card is inserted into a card reader. However, the minimum price of a plastic card is about $2 which is much more expensive than the price of a plastic magnetic stripe card.
Kobayashi et al have described (U.S. Pat. No. 4,304,992) magnetic cards with a timing track or clocking marker along the length of the magnetic stripe can be extended for reader/writer systems to handle speed variation of the card during read/write process. Magnetic heads are moved in sliding contact with the magnetic strips while timing signal that match the speed of the card is obtained from the timing track through detectors such as photo-sensors. Other prior art devices have tried to extract the timing clock from the data on the card using logic gated design.
The read/write system for debit card applications of digital logic design is very complex. Also, when the distance between write head and read head along the magnetic stripe is less than a bit cell length, the written part of the magnetic stripe will shift after each usage. For example, if the distance between read head and write head is one half bit cell distance and the debit card is used 100 times, the flux data on the stripe will shift 1.2 cm. The data flux reversal on the track-2 of the magnetic stripe will shift 1.2 cm.
The wide spread use of credit/debit cards will contribute to bottle necking of the communication lines and also will increase the seriousness of the network security. Thus, there is a need for development of stand alone reader/writer systems that will ease the above concerns. There is also a need for storing data locally, which data can then be sent in less congested times of network use to the appropriate destinations. Further, there is a need for more security that can be embedded into the system by software which in turn will reduce the cost and increase the reliability of the system.
Thus, there is a need for a magnetic card read/writer for debit card applications that will use the written data on the card to accommodate the variation of speed in swipe/insertion utilizing a general use microcontroller. Also, there is a need for a system and method for magnetic card applications that allow for fast read and write operations. The invention herein disclosed fulfills that need, and many others, as will be readily apparent from a reading of this disclosure.
SUMMARY OF THE INVENTION
The novel debit card read/write controller consists of a microcontroller device, a read only memory TOM) means, and a dynamic random access memory (DRAM) means. In the preferred embodiment, all of the components can be integrated into one dedicated chip. The integration of the magneto resistive (MR) read head/thin-film write head with the dedicated chip is described. The controller includes means for reading and writing into magnetic card media. Additionally, a process to integrate all components and chips into a single chip along with the read/write head is disclosed.
The controller may further comprise circuitry means for implementing the microcontroller chip to read and write to the magnetic card media. The microcontroller includes an input capture port for storing data read from the card, and the microcontroller can continually pole the input capture pins for an event to occur. In the most preferred embodiment, the main 16-bit free-running timer system of the MC68C11 series microcontroller has three input capture lines, five output-compare lines, and a real-time interrupt function. The newer version of the MC68C11 allows one output-compare channel to reconfigure as a fourth input capture line. Input lines are used to record timing edges.
The microcontroller operates in an expanded mode and has a memory map from 0000h to FFFFh. The first 256 bytes in all modes reside in the DRAM, a 64 byte register block in the range 1000h to 103Fh, and the final 2000 bytes are in an electrically erasable read only memory (EEPROM). The expanded mode allows for external chips DRAM or EEPROM to be addressed in the remaining ranges of 0100h-0FFFh and 1040h-B7FFh.
In the preferred embodiment, the executable code is stored in the EEPROM beginning at 8000h. The controller further comprises a signal conditioning circuit in a three stage process. In the preferred embodiment, the card contains three magnetic card media tracks. Additionally, the controller can contain output compare function means for comparing the time of the free running clock to match the time in the output compare register to toggle an output pin at each flux reversal to write.
A method for reading and writing to a magnetic strip located on a card is also disclosed. The method comprises providing a message to insert a card containing a magnetic card media and polling the input capture port for an event to occur. The card is inserted into a card reader, with the card reader being operatively associated with a MR read head and thin-film write head. The magnetic card media is passed underneath the MR head, and the information on the magnetic card media is stored in the form of a plurality of magnetic flux reversals. Changes in the resistance is detected by the MR head as the card moves under the MR head which in turn generates an analog signal. The analog signal is conditioned and amplified.
The signal is conditioned to a square wave. The square wave will include time edges containing rising and falling edge data, and the method further comprises storing a time edge at which transitions of the square wave occurs via the microcontroller by means of the input capture ports, with the time data of the edge being stored to the RAM. The method further includes extracting the binary information from the time edges and storing the extracted binary information in the RAM.
In one of the embodiments, the step of polling the input capture ports includes continually checking an interrupt pin to determine if the end of the card has been reached. It should be noted that in one embodiment this may be performed with an optical sensor, and in a second embodiment this may be performed with a micro-switch. The method further includes sending a low signal to an active low IRQ pin from the card reading device, and detecting the low signal by the program. Next, the interrupt service subroutine is entered and the interrupt vector (which is located at the memory address from FFF2h to FFF3h) is retrieved.
In one of the embodiments herein disclosed, the step of conditioning and amplifying the signal includes amplifying the signal with operational amplifiers until the signal is in the form of +5V to −5V analog signal. The signal is then passed through a schmitt trigger and a diode so that the signal is in a digital format (using the TTL logic level) which is the form necessary for use by the microcontroller.
A method of reading from a magnetic striped card with a debit card read/write controller is also disclosed. The method comprises producing a waveform that consist of a series of rising and fall

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