animation ring counter
TRANSCRIPT
-
8/6/2019 Animation Ring Counter
1/43
Questions
Question 1
Animation: Johnson ring counter
This question consists of a series of images (one per page) that form an animation. Flip the pages withyour fingers to view this animation (or click on the next button on your viewer) frame-by-frame.
The following animation shows a 4-bit Johnson ring counter circuit. Watch what happens as the clock
signal oscillates. Here are some things to look for:
Note when the logic state at each flip-flop input gets sent to the Q output.
Why do you think this is called a ring counter circuit?
1
-
8/6/2019 Animation Ring Counter
2/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
0 0 0 0
1
1 0 0 0
2
-
8/6/2019 Animation Ring Counter
3/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
0 0 0 0
1
1 0 0 0
3
-
8/6/2019 Animation Ring Counter
4/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
0 0 0 0
1
1 0 0 0
4
-
8/6/2019 Animation Ring Counter
5/43
-
8/6/2019 Animation Ring Counter
6/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
0 0 0
1
1 0 01 1
6
-
8/6/2019 Animation Ring Counter
7/43
-
8/6/2019 Animation Ring Counter
8/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
0 0 0
1
1 0 01 1
8
-
8/6/2019 Animation Ring Counter
9/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
0 0 0
1
1 0 01 1
9
-
8/6/2019 Animation Ring Counter
10/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
0 0 0
1
1 0 01 1 1 1
10
-
8/6/2019 Animation Ring Counter
11/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
0 0
1
1 01 1 1 1
11
-
8/6/2019 Animation Ring Counter
12/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
0 0
1
1 01 1 1 1
12
-
8/6/2019 Animation Ring Counter
13/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
0 0
1
1 01 1 1 1
13
-
8/6/2019 Animation Ring Counter
14/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
0 0
1
1 01 1 1 1
14
-
8/6/2019 Animation Ring Counter
15/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
0 0
1
1 01 1 1 1 1 1
15
-
8/6/2019 Animation Ring Counter
16/43
-
8/6/2019 Animation Ring Counter
17/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
0
1
1 1 1 1 1 1 1
17
-
8/6/2019 Animation Ring Counter
18/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
0
1
1 1 1 1 1 1 1
18
-
8/6/2019 Animation Ring Counter
19/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
0
1
1 1 1 1 1 1 1
19
-
8/6/2019 Animation Ring Counter
20/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
0
1
1 1 1 1 1 1 1 1
0
0
20
-
8/6/2019 Animation Ring Counter
21/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
1 1 1 1 1 1 1
0
0
21
-
8/6/2019 Animation Ring Counter
22/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
1 1 1 1 1 1 1
0
0
22
-
8/6/2019 Animation Ring Counter
23/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
1 1 1 1 1 1 1
0
0
23
-
8/6/2019 Animation Ring Counter
24/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
1 1 1 1 1 1 1
0
0
24
-
8/6/2019 Animation Ring Counter
25/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
1 1 1 1 1 1 1
0
0 0 0
25
-
8/6/2019 Animation Ring Counter
26/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
1 1 1 1 1
0
0 0 0
26
-
8/6/2019 Animation Ring Counter
27/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
1 1 1 1 1
0
0 0 0
27
-
8/6/2019 Animation Ring Counter
28/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
1 1 1 1 1
0
0 0 0
28
-
8/6/2019 Animation Ring Counter
29/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
1 1 1 1 1
0
0 0 0
29
-
8/6/2019 Animation Ring Counter
30/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
1 1 1 1 1
0
0 0 0 0 0
30
-
8/6/2019 Animation Ring Counter
31/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
1 1 1
0
0 0 0 0 0
31
-
8/6/2019 Animation Ring Counter
32/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
1 1 1
0
0 0 0 0 0
32
-
8/6/2019 Animation Ring Counter
33/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
1 1 1
0
0 0 0 0 0
33
-
8/6/2019 Animation Ring Counter
34/43
-
8/6/2019 Animation Ring Counter
35/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
1 1 1
0
0 0 0 0 0 0 0
35
-
8/6/2019 Animation Ring Counter
36/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
1
0
0 0 0 0 0 0 0
36
-
8/6/2019 Animation Ring Counter
37/43
-
8/6/2019 Animation Ring Counter
38/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
1
0
0 0 0 0 0 0 0
38
-
8/6/2019 Animation Ring Counter
39/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
1
0
0 0 0 0 0 0 0
39
-
8/6/2019 Animation Ring Counter
40/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
1
0
0 0 0 0 0 0 0 0
1
1
40
-
8/6/2019 Animation Ring Counter
41/43
D
C
Q
Q D
C
Q
Q D
C
Q
Q D
C
Q
Q
Clk
2 310
Clock
VDD
Gnd
Q0
Q1
VDD
Gnd
VDD
Gnd
VDD
Gnd
VDD
Gnd
Q2
Q3
0 0 0 0 0 0 0
1
1
file 03234
41
-
8/6/2019 Animation Ring Counter
42/43
Answers
Answer 1
Note that each rising edge of the clock pulse has its own frame in the animation sequence, to better
show you what happens at those crucial times.
42
-
8/6/2019 Animation Ring Counter
43/43
Notes
Notes 1
The purpose of this animation is to let students study the behavior of this counter circuit and reach
their own conclusions. Similar to experimentation in the lab, except that here all the data collection is done
visually rather than through the use of test equipment, and the students are able to see things that are
invisible in real life.
In this animation, I show each rising edge of the clock signal in its own frame, whereas the falling edge
of the clock shares a frame with the first half of the low state. I do this because these are positive edge-
triggered flip-flops, and so the rising edge of the clock pulse is most important. I could have slowed things
down on the falling edge of the clock as well, but since there is little action happening then, I decided to
save a frame and make it a shorter animation.
43