see attachment

c©A.H.Dixon CMPT 150 : ASSIGNMENT 3 1

Due 23:59 Monday, October 28, 2013 (1 page)

1. The following behavioural description defines a 1-bit counter:

Q cl up Q+ c

0 0 0 0 0
0 0 1 1 0
0 1 0 0 0
0 1 1 0 0
1 0 0 1 0
1 0 1 0 1
1 1 0 0 0
1 1 1 0 0

(a) Construct the characteristic equation and output equation for CTR1.

(b) Construct the excitation table for CTR1, assuming cl = 0. That is, determine the value of up
that causes CTR1 to make each of the four possible state transitions, assuming cl = 0.

(c) Construct and test a schematic for CTR1 using Designworks gates and D flip-flops wo/RSQ.
NOTE: To initialize the circuit, click on “clear values” in the “Simulation” pull down menu.

(d) Package your implementation of CTR1 and place it in your personal Designworks library.

2. Design an incrementing mod-8 counter using only CTR1 components and a minimal number of gates
and construct its schematic in Designworks. To observe the count sequence, connect the appropriate
outputs from the CTRT1 components to a hex display. Also generate a waveform diagram.
NOTE: As observed in the characteristic table, when cl = 1 the next state is always 0. Therefore your
input function table should depend only on the present state and the value of up.
HINT: The c output has a role to play in simplifying the implementation. Look for expressions in your
mod-8 counter input functions for each CTR1 that are equivalent to the expression defining c.

3. Package your solution to the previous question as a Designworks component named “CTR8” and save
it in your personal Designworks library.

4. An incrementing mod-6 counter is to be constructed in two ways:

(a) Using CTR1 components and gates, much as you did in obtaining your solution for CTR8 in (2).

(b) Using a CTR8 component and gates. In this case you will need to construct a combinational
circuit that tests when the final value in the count sequence has been reached and uses this result
to reset CTR8.

For each version of your mod-6 counters you should generate a waveform diagram that demonstrates
that the circuits function correctly.

Place all tables, equations, circuit files (.cct), and waveform diagrams in a folder named “Assign3”. Then
place the folder in a zip file named “Assign3.zip” and submit it via the Course Management System.