Summary and Discussion

2.1 What Did Unknown Talent Learn from this Project? The P-1.00 Alarm System was designed with one major goal in mind: to familiarize ourselves with the functions of the Motorola HC12 and the Altera 7000 series chips. This project also allowed us to work in a group setting which is an essential part of becoming engineers. A large portion of this assignment was understanding how to interface different pieces of hardware into one single unit in order to produce one effective and functioning alarm system. We made use of an external motion sensor as well as a custom built 6 button keypad which served as our "off board" inputs. A consequence of the motion sensor light was the apparent need for devices which would allow:

a) the conversion of 120Vac - 5Vdc, and b) the elimination of the long capacitance delay which occured as a result of the adapter used to solve a)

With some research and help from several faculty members, we were able to facilitate these hardware necessities and produce effective components, namely our opto isolator which Gary Lau spent a lot of time researching and building. Hardware, although a large portion of this project, was only part of the project. The programming involved in controlling the Motorola HC12 and the Altera chips took the longest to complete. The Motorola HC12 programming made an extensive use of IRQ interrupts, making it possible to effectively and efficiently detect all of the inputs which made up our system. The Altera programming us to gain experience in connecting and recognizing different external components onto the EVB. We had to cause one LED to light up when any button is pressed or movement is detected by the motion sensor. In addition we had to properly transmit siganls to the HC12 in order to inform it which button has been pressed. The code listings can be found in our CODE section.

2.2 A Brief Summary of Our Project The P-1.00 Prototype Alarm System is comprised of five basic components. A 6-button keypad allows the user to arm and disarm the alarm system with a password which he/she will make up. Four push buttons, located on the EVB (evaluation board) as well as one motion sensor light, act as the inputs which simulate the monitoring devices for the alarm system. A siren is used as an audio output which informs the user as to the status of the alarm, and an LCD display screen is used as the visual status indicator. At the center of it all there lies the EVB which is comprised of the Motorola HC12 and Altera 7000 series chips. This portion of the project serves as the "brain" and "controller" of the whole system, allowing the user to make use of the password feature as well as allowing the status to be indicated on the LCD screen. In addition, the components on the EVB allow for the sounds which are produced and controls and manages all of the inputs which we have incorporated into our design.

2.3 Difficulties We Encountered The most difficult aspect of our project was learning how to interface external components with the supplied EVB which was comprised of the Altera and Motorola chips. The motion sensor light and the keypad were the most essential parts of the system and also two of the most difficult components for us to connect to the board. Once this hurdle was overcome, it was simply a matter of using our knowledge from our first three assignments as well as the knowledge collected from other courses to program the chips which controlled all of the operations. The only main challenge which we encountered when programming, was the task of incorporating a password function into our unit. These challenges were overcome and the product, we feel, is of high quality.

2.4 Alternative Solutions / Improvements and Future Work Major alternative solutions could have been implimented in our hardware and basic alarm function which we created.

a) Our keypad could have been upgraded to any size allowing for more possible password combinations and thus a more secure system. This upgraded keypad, in order to be most effective, would most likely be based on a matrix system. Each button would be identified by a horizontal as well as a vertical co-ordinate byte. Thus, for a 3x4 button keypad, 7 output bytes would be required; for a 4x4 button keypad, 8 would be needed; and so on. As can be seen, this matrix based system is better in that fewer outputs would be required to identify the button pressed. b) We could have opened up the motion sensor light and "tapped" the voltage at some place where the voltage was around 5V dc. The reason that Unknown Talent did not attempt this was because of a little "Warranty Void if Seal Broken" sticker. We wanted to return the light afterwards so opening it up was not an option! For us, using the opto isolator and adaptor combination proved to be sufficient for our project as well as a good learning experience. c) We could have added more features and options with regards to the program itself. In a real alarm system, generally certain zones can be by-passed if the user wishes. Disabling the motion sensor, for example, would be preffered if the users were, say, going to be at home and only want to monitor the doors and windows (simulated by the 4 buttons on the EVB).

There were many different possibilities when it came to displaying the status on the LCD. As we were not entirely sure how much memory we would have left in the end, we chose to go with a simple, clear and concise display. Depending upon what the user might want, the dsplay could be modified very easily in order to make the alarm a more "custom" unit. We feel that we have built a very efficient, simple and reliable base unit. If desired, this "base" could be expanded and added on to (i.e. adding more inputs, changing the keypad, changing the display readout), which could produce a more attractive and perhaps more interesting display.

Introduction User's Manual Project Design Code Listing Team Members