Random Keypad System

Random keypad system is the system where the number or symbol on keypad buttons is changing randomly during operation. This feature can reduce the chance of password being stolen by the bystander during the password entry process. The onlooker will have difficulty to see what number is being pressed by watching the finger movement as the location of the numbers is placed randomly.

HIRSCH ScramblePad is a random keypad where the number is displayed randomly on it as displayed in Figure 2.10 [43]. The number positions are placed randomly on the keypad before the password entry. The keypad button is built by LED seven segment display with the restriction of the light wave in certain direction.

This caused the numbers only to be visible within certain angle. This can prevent others to read from the side plus it is hard to guess the code by watching the movement of the user’s finger.

Figure 2.10 : Keypad of ScramblePad from HIRSCH

Another random key system is the PINSAFE software form Swivel as demonstrated in Figure 2.11[44]. It provides user a set of random number combination from 0 to 9 during the time that user try to login. User is required to remember 4 numbers at the location of their original password and insert the 4 numbers during the login process. This method can prevent others from knowing the real password even when they have watched the login process. Besides, they can resist the attack on key logger as the entered number is not the real password.

Figure 2.11 : Operation flow of the Swivel PINSAFE

2.8 Arduino

Arduino is a microcontroller that acts like a mini computer to perform specified function. It can be programmed to manipulate the collected data from the input and control the connected output peripheral. It is usually applied in the embedded system where it interacts with the surrounding via its combination of hardware and software. There are a lot of applications of Arduino as long as there is a loaded program to command the input devices (usually sensors or keypad) and the output devices (such as the LED or LCD screen) connected to the board [45][46].

Basically, the Arduino board consists of several main parts in a single board, such as processor, power supply, Input/output ports, USB Port and extension connectors. Arduino is an Atmel based Microcontroller. The Atmel Microprocessor is used as the brain for all Arduino modal. A voltage regulator is soldered in the Arduino board which receives the unregulated voltage from the range of 7V-12V to produce a regulated 5V DC to the circuit. The supply is connected to the power jack to get the external power source [45][46].

Besides, a crystal clock is used to generate the clock pulse (“heart beat”) for the microprocessor to process in stable time for each cycle. The number of input/

output ports is varied according to the modal of the Arduino as the microprocessor for each modal is different. The USB Port is mainly used for connecting the Arduino with the computer during program burning. Apart from that, the USB port also supplies the 5v voltage directly from the computer. It means that there is no need for other external source to power up the Arduino when it is connected through the USB.

However one has to bear in mind that the current from the USB port may not be enough for other bigger output loads such as, relays, motor and etc. As the microprocessor type in each Arduino is different, the number of extension connector (usually located at the side of the board) is also different. These extension connectors are a user friendly feature where it provides the direct ports for the user to connect the input/output pins of the IC [45][46].

The reason of Arduino is chosen as the controller in this project is because there are many shields with different function that can be added when it is modification is needed. Another reason to choose Arduino is due to the open source of its hardware and software. It means that it can be used commercially without copyright issue. Furthermore, the program burning process of Arduino is also simple as it only needs to connect the USB cable between Arduino and the computer. This will save a lot of money and programming time as it does not need to connect to the programmer [45][46].

2.8.1 Arduino Mega 2560 R3

The modal of Arduino in this project is the Arduino Mega 2560 R3. It can work with the power supply of 6-20V but the optimal range is 7V -12V. The overheat problem may be encountered if the supply exceed 12V; whereas the insufficient voltage regulator’s output will happen if the input of the regulator is less than 7V. Besides, there is a 3.3V regulator used on the board with the ability of supplying a 50mA current [47].

It used Atmega2560 chip as the processor. According to the Atmel Datasheet for the ATmega2560, it is an 8-bit high efficiency chip as its power consumption is small. The RISC architecture is applied in this processor where the execution of the instruction is quicker than the CISC architecture [47].

There is a 256Kbyte of flash memory, 8k byte of internal Static Random Access Memory and 4k byte of Electrically Erasable Programmable Read Only Memory. The write/ erase cycle for Flash memory and EEPROM are 10K times and 100ktimes respectively. The 16 mega Hertz crystal is used to supply the clock pulse for the chip.

Besides, there are 54 Input/output pins in this model. The 12 ports are varied from port A to port K. All ports are 8 pins accept the port G with only 6 pins. It also consists of 32 General Purpose Registers. Among these I/O pins, there are 16 pins for analog input, 15 pins for PWM output, 3 sets of serial communication interface and 1 set of Serial peripheral Interface as well as 2-wire Serial interface [47]. The output connection of Atmega 2560 is shown in Figure 2.12. The whole schematic diagram is shown in APPENDIX A.

Figure 2.12 : Input output connection of Atmega 2560