Algonquin College
Of Applied Arts and Technology
ELE8930 Lab 5 Sequential Logic Circuits
Part 1: The RS Flip Flop
Objectives:
i.
ii.
iii.
To wire and observe the operation of an RS flip flop.
To wire and observe the operation of a clocked RS flip flop.
To study how flip flops are used as a units of memory.
Equipment:
7400 2-input NAND gate IC
555 Timer circuit from lab 1
Procedure:
1.
Complete the wiring diagram of schematic 1 for the RS flip flop shown in the figure 1. Use two
2-input NAND gates.
figure 1
Sw-1
S
Q
S
FF
R
Q
R
Sw-2
Q
__
Q
Schematic 1
1
Algonquin College
Of Applied Arts and Technology
2.
With the power off, construct the circuit from step 1. Use two output LED indicator lights with
resistors.
3.
Turn power ON. Operate the input switches to the positions shown in the input section of
Table 2. Using table 1 as a reference, observe and record the output of each circuit in the
output part of table 2.
4.
In the right column of table 2 write the name of the condition of the outputs. Use the terms
hold, set, or reset.
Table 1: Truth Table for a RS Flip Flop
Mode of
Operation
INPUTS
OUTPUTS
S
R
Q
__
Q
Prohibited
0
0
1
1
Prohibited - Do not use
Set
0
1
1
0
For setting Q to 1
Reset
1
0
0
1
For setting Q to 0
Q
__
Q
Hold
1
1
Effect on Output Q
Depends on previous
state
TABLE #2
INPUTS
5.
S
R
0
0
0
1
1
0
1
1
0
1
1
1
1
0
OUTPUTS
Q
__
Q
Mode of Operation
(Prohibited, Set, Reset, Hold)
Proceed to part 8 and leave this part of your lab assemble.
2
Algonquin College
Of Applied Arts and Technology
6.
Complete the wiring diagram of schematic 2 for the RS flip flop shown in the figure 2. Use
four 2-input NAND gates.
Figure 2
Sw-3
S
Q
CLK
CLK
FF
R
Sw-4
Q
9.
With the power off, construct the circuit from step 6. Wire the input switches to R and S and
the single pulse clock input CLK from the 555 timer circuit. Use two output LED indicator lights
with resistors.
10.
Turn power ON. Operate the input switches to the positions shown in the input section of
Table 4. Using table 3 as an reference, observe and record the output of each circuit in the
output part of table 4..
11.
In the right column of table 4 write the name of the condition of the outputs.
3
Algonquin College
Of Applied Arts and Technology
TABLE 3 - Truth Table for a Clocked R-S Flip Flop
INPUTS
Mode of
Operation
OUTPUTS
Q
__
Q
S
R
Effect on output Q
Hold
0
0
Reset
0
1
0
1
Reset or cleared to 0
Set
1
0
1
0
Set to 1
Prohibited
1
1
1
1
Prohibited-do not use
No Change
No Change
TABLE 4
INPUTS
OUTPUTS
CLK
S
R
↑
1
0
↑
0
0
↑
0
1
↑
0
0
↑
1
0
↑
1
1
↑
1
0
↑
0
1
↑
0
0
↑
1
0
Q
__
Q
Mode of Operation
12.
Move the clock input to one of the logic switches and repeat the steps in the table above.
13.
Show the instructor your results.
INSTRUCTORS INITIALS:________
4
Algonquin College
Of Applied Arts and Technology
Part 2 - The D Flip Flop
Objective:
To operate and test D flip flops using a 7474 IC.
Material:
7474 D-type flip flop IC
555 Timer circuit from lab `1
Procedure:
1.
Insert the 7474 IC into the mounting board.
2.
Refer to figure 3 and the pin-out for the 7474. Wire D, CLR, and PS to switches and CLK to
the output of the 555 timer circuit. Wire Q & Q NOT to LEDs.
Figure 3
7474 D-type Flop Flop pin-out
CLR-Sw-2
Sw-3
Q
D
FF
(7474)
CLK
Q
PS-Sw-1
4.
Turn power ON, using table 5 as an reference, fill in table 6. In the right-hand column of Table
2, write the mode of Operation.
5
Algonquin College
Of Applied Arts and Technology
TABLE 5 - Truth table for a D Flip Flop
INPUTS
Asynchronous
Mode of Operation
Synchronous
OUTPUTS
PS
CLR
CLK
D
Q
__
Q
Asynchronous Set (PS)
0
1
X
X
1
0
Asynchronous Reset (CLR)
1
0
X
X
0
1
Prohibited
0
0
X
X
1
1
Set
1
1
↑
1
1
0
Reset
1
1
↑
0
0
1
X = Irrelevant,
↑ = Low to High Transition of Clock Pulse
TABLE 6
INPUTS
Asynchronous
5.
OUTPUTS
Synchronous
PS
CLR
CLK
D
0
1
X
X
1
0
X
X
0
0
X
X
1
1
↑
1
1
1
↑
0
1
1
↑
1
1
0
↑
1
1
1
↑
1
1
1
↑
0
0
1
↑
0
__
Q
Mode of Operation
Move the clock input to one of the switches and repeat the steps in the table above. Next
slowly pulse the D flip-flop (start at 0, then 1, and then 0). Can you determine if the flip-flop is
positive or negative edge-triggered?
Circle the correct answer →
6.
Q
Show the instructor your results.
Positive or Negative
INSTRUCTORS INITIALS:________
6
Algonquin College
Of Applied Arts and Technology
Part 3 - The JK Flip-Flop
Objective:
To operate and test JK flip flops using a 7476 IC.
Material:
7476 JK flip flop IC
555 Timer Circuit
Procedure:
1.
Refer to the figure 4 and the pin-out diagram for the 7476 dual JK flip flop. Wire J, K, CLR,
and PS to switches and CLK to the output of the 555 timer circuit. Wire Q & Q NOT to LEDs.
Figure 4
7476 JK flip flop
CLR-Sw-2
Sw-3
J
CLK
CLK
(7476)
Sw-4
K
Q
Q
PS-Sw-1
4.
Turn power ON, using table 7 as a reference, fill in table 8. In the right-hand column of Table
8, write the mode of operation.
5.
Move the clock input to one of the switches and repeat the steps in the table above.
6.
Show the instructor your results.
INSTRUCTORS INITIALS:________
7
Algonquin College
Of Applied Arts and Technology
Table 7 - Truth Table for a JK flip flop
INPUTS
Mode of Operation
Asynchronous
OUTPUTS
Synchronous
PS
CLR
CLK
J
K
Q
__
Q
Asynchronous Set (PS)
0
1
X
X
X
1
0
Asynchronous Reset
(CLR)
1
0
X
X
X
0
1
Prohibited
0
0
X
X
X
1
1
Hold
1
1
↓
0
0
No Change
Reset
1
1
↓
0
1
0
1
Set
1
1
↓
1
0
1
0
Toggle
1
1
↓
1
1
Opposite State
X = Irrelevant, ↓= High to Low to Transition of Clock Pulse
TABLE 8
INPUTS
Asynchronous
OUTPUTS
Synchronous
PS
CLR
CLK
J
K
0
1
X
X
X
1
0
X
X
X
0
0
X
X
X
0
1
X
X
X
1
1
↓
0
0
1
1
↓
0
1
1
1
↓
1
0
1
1
↓
1
1
1
1
↓
1
1
1
1
↓
1
1
1
1
↓
1
1
Q
_
Q
Mode of Operation
Prohibited
PS, CLR, Hold, Reset, Set,
Toggle
8
Algonquin College
Of Applied Arts and Technology
*Part 4: Ripple Counters
Objectrive:
i.
To wire, and test a 4-bit ripple up counter using JK flip flops.
ii.
To design, wire and test a module-10 ripple counter with digital readout.
MATERIAL 7400 2-Input NAND Gate IC
Seven-Segment LED Display
7 - 150 Ω, 1/4-W Resistors
2 - 7476 dual J-K Flip-Flop ICs
7447 BCD-to-Seven-Segment Decoder/Driver IC
555 Timer Circuit
*SYSTEM DIAGRAM:
This lab has three circuits that you will partially design, construct, and test in this experiment. You
must design and draw in detail the counters. You will use flip flops when designing these counters.
The counter in the third circuit will require a NAND gate.
PROCEDURE:
To L1
Figure 5
Qd
Clock
Input
4-Bit
Ripple
UP
Counter
D
L2
C
L3
B
L4
A
Qc
Qb
Qa
1.
Design a 4-bit, Mod 16, ripple up counter as shown in figure 5 above. Use four JK flip-flops
and four output LED indicator lights with resistors.
4-bit Mod 16 ripple UP counter using JK flip flops:
9
Algonquin College
Of Applied Arts and Technology
2.
Connect power (Vcc) and GND to each 7476 IC. For proper operation connect the following
pins to Vcc, J, K, PR, and CLR.
4.
Wire the circuit you drew in step 1. Connect CLK input to a single pulse clock. Wire the 7476
ICs and the four output LED indicator lights with resistors.
5.
Turn power ON. Operate the 4-bit counter. Observe and record the results in the 4-bit ripple
up counter column, Table 9.
TABLE 9
INPUT
Pulse
Number
0
OUTPUTS
4-Bit Ripple
UP Counter
4-Bit Ripple
DOWN Counter
D
C
B
A
D
C
B
A
0
0
0
0
1
1
1
1
Decade Counter
with
Digital Readout
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
6.
Show the instructor your results.
INSTRUCTORS INITIALS:________
10
Algonquin College
Of Applied Arts and Technology
Figure 6
Qd
Preset
Clock
Input
7.
4-Bit
Ripple
DOWN
Counter
D
C
B
A
Qc
Qb
Qa
Design a 4-bit ripple DOWN counter shown in the figure above. Notice the addition of a PS
input for setting the output of the counter to 1111.
4-bit Mod 16 ripple DOWN counter using JK flip flops:
8.
Turn power Off. Rewire the 7476 J-K flip-flops to get the down counter you drew in step 7.
9.
Turn power ON. Preset (PS to 0 and then back to 1) the outputs to 1111.
10.
Operate the down counter by pulsing the CLK input. Observe and record the results in the 4bit ripple down counter column, Table 1.
11. Show the instructor your results.
INSTRUCTORS INITIALS:________
11
Algonquin College
Of Applied Arts and Technology
Figure 7
Digital Readout
Clock
Input
Qd
Module
10
Ripple
UP
Counter
Qc
Qb
Qa
“8”
“4”
“2”
“1”
7447
Decoder
a
b
c
d
e
f
g
a
b
c
d
e
f
g
a
f
g
e
b
c
d
150
+ 5 V (Common Anode)
12.
Design a module-10 ripple UP counter as shown in figure 7 above. Use four JK flip-flops
(7476 IC and one 2-input NAND gate (7400 IC).
Module-10 ripple UP counter
13.
Construct the counter. Insert the 7447 IC and the seven-segment LED display closely together
on the mounting board. Wire the input CLK, the two 7476 ICs, and the 7400 IC. Wire the
counter outputs (QD, QC, QB, QA) to the inputs of the 7447 decoder (D, C, B, A). Connect
seven 150 Ω limiting resistors between the 7447 decoder and the seven-segment LED display.
12
Algonquin College
Of Applied Arts and Technology
14.
With the power OFF, connect power (Vcc) and GND to the 7447 IC. Connect +5 V (Vcc) only
to the seven-segment LED display.
15.
Turn power ON. Operate the module-10 counter by pulsing the input. Observe and record the
results in the decade counter with digital readout column, Table 1.
19.
Show the instructor your results.
INSTRUCTORS INITIALS:________
Part 5 - IC Counters
Objecives: To wire and test a up and down counter using a 74192 IC.
Material
74192 up/down counter IC
SYSTEM DIAGRAM:
The 74192 Up/Down Decade Counter is a synchronous decade (base-10) counter that counts in
either direction.
For normal up-counting sequence, “Load” should be high, and “Clear” should be low. When upcounting, hold the “Down-Count” input high. When down-counting, hold the “Up-Count” input high.
Vcc +5 v
Figure 8
Clock
Pulse
5
Vcc
11
GND
14
16
7
6
74192
Vcc
4
2
3
Qd
Binary LED Readout
D
B
C
A
Qc
Qb
Qa
8
Decoder
GND
“8”
“4”
“2”
“1”
7447
Digital Readout
a
b
c
d
e
f
g
a
b
c
d
e
f
g
a
f
g
e
b
c
d
150
+ 5 V (Common Anode)
13
Algonquin College
Of Applied Arts and Technology
Procedure:
1.
Insert the 74192 into the proto board and wire up the counter as shown in figure 8 on the
previous page.
2.
Turn power ON and observe the counter sequence. The 74192 should count from 0 to 9.
3.
Show the instructor your results.
4.
Rewire the 74192 (See system diagram) for down-counting sequence. The 74192 should now
count downward from 9 to 0.
5.
Show the instructor your results.
INSTRUCTORS INITIALS:__________
INSTRUCTORS INITIALS:__________
14