QUESTION $4$ Attempt ALL Sections $[30$ marks$]$

a$)$ A microcontroller is used to control an automated garage door. The garage

door is to be operated using two push button digital inputs for the open

and close functions. Two limit switch digital inputs are provided to detect

when the garage door is fully open and fully closed. The door is actuated

using a motor, which is controlled from two digital output pins on the

microcontroller, open door output and close door output.

i$.$ Develop a UML Activity Diagram for the system showing the following

states; Door Closed, Door Opening, Door Open and Door Closing.

$(5$ marks$)$

ii$.$ Select suitable I$/$O pins on the Arduino microcontroller platform for the

application described above. Develop an application program in $"C"$

language or Arduino Wiring language to implement the Activity Diagram

developed in part $($i$)$ above for the system.

$(10$ marks$)$

b$)$ Microcontroller Interfacing:$-$

i$.$ Explain using a diagram how an external parallel LCD display could be

connected to the Arduino microcontroller. Show any additional

components or connections which would be required. Give details of

how the LCD display would be initialised in software using the

Arduino LCD library.

$(10$ marks$)$

ii$.$ Show how a simple push button could be connected to a digital input

on a microcontroller. Explain the purpose of any additional hardware

required when connecting the push button to the microcontroller.

$(5$ marks$)$