As the hard drive spins at 7200 RPMs, the sensor will capture exactly when the reference
point on the hard disk passes. The LEDs will then flash red, green, or blue
at specific times after the sensor is triggered to display the three hands of an
analog clock. The LED lights will only be visible through a slit in the hard
disk. The flashes will be so rapid that the human eye will interpret them
as a single bar of constantly illuminated light.
Components and Their Functionality:
Sensor:
The light sensor is a combination of a laser pointer and a phototransistor.
This is used to figure out exactly where the reference point on the hard disk is.
NES Controller:
The 8-bit Nintendo Controller is used to set the hands of the clock
as well as the alarm time. The alarm can be enabled and disabled with the start
button.
LED Lights:
A signal is sent to all 19 RGB LEDs indicating exactly when each color
should flash in order to display the time.
LCD Display:
When the alarm is not triggered, the LCD will display the reference
time of the three hands in hexadecimal indicating when each hand should flash. When
the alarm is triggered, the LCD will display a simple math problem that does not
allow the alarm to be shut off until the correct answer is pressed.
Numeric Keypad:
The keypad allows the user to answer the math problem in order
to shut the alarm off.
Hard Drive Actuator:
The actuator moves back and forth once every second to act
as a ticker for the clock. When the alarm is triggered, the actuator moves much
quicker and outputs a pulsing alarm noise.
DC Motor:
The DC Motor spins a flag once every second when the normal time is displayed
and spins up with the alarm sound when it is triggered.