The first four ports are connected to the columns meanwhile the last four are connected to the rows. Moreover, as a justification for this reasoning is the fact that it is required to scan the columns for the pressed key and then scan the rows and the results will be decoded in a decoder telling us which button of the keypad was pressed. The main
functionality of the keypad as mentioned earlier is to set the code. The alarm can be armed and disarmed with a standard four digit user code in our case. The master code is a step above a regular user code. It is used to unlock the system, as well as programming or erasing a regular user code. Theoretically it can also be used to bypass some sensors. The default password set during the design, which is also the installation code, is 1234. Most alarm companies use the same installer code for all of their installations, and the vast majority will never give their installer code to a customer, for obvious reasons. As soon as we connect the 5V power source the alarm greets
us with a welcome message displayed on the LCD then asks us to provide the password. Once entered correctly the green LED flashes accepting the code.