Introduction The digital clock makes use of two types

Introduction
The digital clock makes use of two types of counters. The mod 10 counter and
mod 6 counter. The mod 10 counters are connected to count units’ value for
seconds, minutes and hour. The mod 6 counters are used to count tens place
value for seconds and minute values. The ten’s value for hour is counted using
single T flip flop.
The reset circuit causes the clock to return o initial value of all 0 when ever clock
reaches the count of 12:00:00.
Mod 10 counter are 4 bit counters built using 4 T flip flops and reset circuit that
reloads counter to 0 when it reaches count of 10. So counter only counts value
from 0 to 9. As it rollovers from 9 to 0. It also generates a signal that is used to
enable the next stage counter. Similar structure is used for mod 6 counter, but it
only counts from 0 to 5 and rollovers at 5. Both of the counters are connected
alternately in a cascaded manner.
Mod -10 Counter.
Enable signal allows the counter to count up on each incoming clock. If enable is
held low. The clock will not increment the counter. Secondly if counter reaches a
value of 1010, the reset signal is generated internally to reset the counter to 0.
Next signal is generated when counter is enabled and has reached it’s maximum
value 9 in case of mod 10 counter.