# LOGIC DESIGN QUESTION!!!NEED HELP!!!? Digital Clock

#### lili1271

Joined Mar 29, 2012
1
I m just asking for a little bit of help on how to start.
I would appreciate it if someone gives me some directions.
here is the project:

Design the control logic for an alarm clock (for simulation purposes 20ns simulation = 1 minute real
time  this can be adjusted somewhat for simulation purposes but not to overly simplify the design).
a. Use multiple input signals (alarm set input, the snooze, and the alarm time).
b. The design will contain one output (Alarm_On). A logic high at the output represents the alarm
being on.
c. A set of input switches (manual toggle style switches) will be used to set the time the alarm
should go off at.
d. When the simulation starts, and internal counter (created by the group as part of the design) will
start counting (representing/roughly simulating a clock).
e. If the alarm set input signal (use an input signal part) is high, then the alarm should turn on when
the internal count equals the preset alarm value. If at any point during the simulation the alarm
set input is switched off, the alarm should turn off by the next complete clock cycle.
f. If the snooze button is activated (generate a pulse using the input signal part that is at least one
full clock cycle in duration) the alarm should turn off and then turn back on after 5 minutes.
g. Repeat snooze button simulations (pulses) should cause the same behavior in the circuit so this
portion of the circuit needs to be able to reset itself.
h. If at any time the alarm set input signal goes low, the Alarm_On output should go low by the end
of the next complete clock cycle.
i. You must figure out how you want to control the Alarm_On output signal and the logic needed
for this design.
j. Counter(s) and not input signals must be used to trigger the timing related aspects of this design
(ex. snooze for 5 min, count to preset alarm setting).

#### wayneh

Joined Sep 9, 2010
17,175
I m just asking for a little bit of help on how to start.
I assume this is school homework? You should start by doing a good bit of this first yourself, and then come back for refinements and suggestions. I'd probably start by drawing a block diagram of the logic, and then figure out how to execute that with a microprocessor.

#### rfredel

Joined Jan 23, 2011
25
Hello,

[(for simulation purposes 20ns simulation = 1 minute real
time – this can be adjusted somewhat for simulation purposes but not to overly simplify the design/QUOTE]

I think there will be a mistake in writing. 20ns will be a clock frequency of 50MHz. With this clock frequency you will not see any changes of the time. Do you mean 20ms or 200ms? that will be a practicable frequency.

Regards
Rainer

PS: Sorry, if my English is not so good.

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