Lecture 6
Binary Counter
Thinking Digitally
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Henry Farny’s Song of the Talking Wire
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2 Minute Quiz
Name_______ Sec_______Date_______
• Code Example:
• Code Example:
• Code Example:
• PWM Question:
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Joseph Henry & the Telegraph
•
•
•
•
Albany Academy Experiment
Assisted Morse at Princeton
1st Head of Smithsonian
Unit of inductance: Henry
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Morse Code
• Simple sequences of short
and long clicks to represent
letters and numbers
• Easier to generate than
sound
• Easier to distinguish than
sound
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UPC Codes
•Bars come in four
widths 1-2-3-4
•Start is 1-1-1 (blackwhite-black)
•
•
•
•
•
•
•
•
•
•
0 = 3-2-1-1
1 = 2-2-2-1
2 = 2-1-2-2
3 = 1-4-1-1
4 = 1-1-3-2
5 = 1-2-3-1
6 = 1-1-1-4
7 = 1-3-1-2
8 = 1-2-1-3
9 = 3-1-1-2
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•
•
•
•
•
•
•
The zero is 3-2-1-1 (space-bar-space-bar).
The four is 1-1-3-2 (space-bar-space-bar).
The three is 1-4-1-1 (space-bar-space-bar).
The next three zeros are 3-2-1-1 (space-bar-space-bar).
In the middle there is a standard 1-1-1-1-1 (space-barspace-bar-space), which is important because it means
the numbers on the right are optically inverted!
The one is 2-2-2-1 (bar-space-bar-space).
The stop character is a 1-1-1 (bar-space-bar).
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Computer Number System Examples
From Computer Science I
10110101110001011001110011110110
11
B
5
5
12
C
5
9
5
12
9
B5C59CF6
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C
15
F
6
binary number
equivalent base 10 value for
each group of 4 consecutive
binary digits (bits)
6
corresponding hexadecimal
(base 16) digit
equivalent hexadecimal
number
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Communicating With Pulses
• PCM: Pulse Code Modulation
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PCM: Pulse Code Modulation
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PWM: Pulse Width Modulation
• Signal is compared to a sawtooth wave
producing a pulse width proportional to
amplitude
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Optical Receiver
• Receiver detects pulses of light
• Pulses are amplified and partly averaged by 741 opamp (volume adjusted with the pot)
 Higher frequencies still in signal cannot be heard
• Signal is increased by 386 audio amp
• 386 audio amp drives the speaker
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Optical Transmitter
• Audio signal changes thresholds for 555
timer producing a type of pulse width
modulation of the light from the LED.
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Signals from Audio Remote
54603B, CHAN1, 09:22, 9/20/2002
54603B, CHAN1, 09:23, 9/20/2002
8
8
6
6
4
4
2
2
0
0
20.0 ms/
5.00 ms/
Mostly hear higher frequencies in pulses
3.5 x 20 = 70ms or 14Hz
54603B, CHAN1, 09:24, 9/20/2002
54603B, CHAN1, 09:25, 9/20/2002
8
8
6
6
4
4
2
2
0
0
500 us/
4 x 500 = 2000us or 500Hz
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100 us/
2 x 100 / 9 = 23us or 43kHz
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Binary Numbers
0
1
2
3
4
5
0000
0001
0010
0011
0100
0101
6
7
8
9
10
11
0110
0111
1000
1001
1010
1011
Byte
Lower Nibble
Upper Nibble
Bit
7
Bit
6
Bit
5
Bit
4
Bit
3
Bit
2
Bit
1
Bit
0
1
0
1
1
0
1
1
1
2
128
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7
+
2
+ 0
6
+
+
2
5
+
32 +
2
4
3
+
2
+
16 +
0
+
2
1
2
4
+
+
2
0
=183
2
+
2
Binary
number
+
1
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=
183
14
Binary Counter
• Animations showing counter operation
http://www.play-hookey.com/digital/synchronous_counter.html
• Counter for lab
1
2
9
10
7
6
5
4
3
CL
CLK
LD
TE
PE
CO
P4
P3
P2
P1
Q4
Q3
Q2
Q1
15
11
12
13
14
14161
2
-
+
1
5V
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Typical Output for Binary Counter
• Note how the Q outputs form 4 bit numbers
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Digital Pulses
• Function generator produces a 1kHz
sinusoidal voltage. 1v peak-to-peak (pp)
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Digital Pulses
• Switch to a square wave at 1kHz. Still
1v pp
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Digital Pulses
• Add a 0.5 volt offset so that the square wave
goes from 0 volts to 1 volt
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Digital Pulses
• Now the duty cycle is adjusted to 20% to see
what a single digital pulse looks like.
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10
10
8
8
6
6
4
4
Pulse Voltage
Pulse Voltage
Pulses on a Transmission Line
2
0
-2
2
0
-2
-4
-4
-6
-6
-8
-10
0
0.2
0.4
0.6
Distance Along The Line
0.8
1
From
Matlab
-8
-10
0
0.2
0.4
0.6
Distance Along The Line
0.8
1
• Pulses propagate down transmission lines at the
speed of light. They reflect off of the load if the load is
not the same impedance as the line. Lines, sources
and loads must be matched.
• Cable TV lines are 75 ohms. Cables in the lab are
typically 50 ohms.
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What Can Be Done With PWM?
Low
Duty Cycle
Medium
Duty Cycle
High
Duty Cycle
• Question: What happens if voltages like
the ones above are connected to a light
bulb? (4th 2 Minute Quiz Question)
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What Can Be Done With PWM?
• Average power can be controlled
• Average flows can also be controlled by fully
opening and closing a valve with some duty
cycle
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What About Analog Modulation?
• AM: Amplitude
Modulation
• FM: Frequency
Modulation
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Other Coding Applications
• Cryptography
• Image Compression





JPEG (Joint Photographic Expert Group)
GIF (Graphics Interchange Format)
TIFF (Tagged Image File Format)
MPEG (Compression of Motion Video)
Most use Discrete Cosine Transform
method
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Image Compression
2 bpp
0.5 bpp
24 bpp original
(bits per pixel)
Top: JPEG
Bottom: JPEG2K
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2 Minute Quiz
ANSWERS
• Code Example: MORSE, UPC
• Code Example: BINARY
• Code Example: PWM
• PWM Question: The longer the duty cycle, the
longer the light bulb is on and the brighter the
light
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Where Will You See This Material Again?
• 555 Timer – IEE Lab 6
• Digital Counter – IEE Lab 7
• Counters: ECSE- 2610 Computer Components
and Operations, ENGR-2350 Introduction to
Embedded Control
• Signals and Transforms: ECSE-2410 Signals and
Systems
• Pulse Width Modulation: Embedded Control,
ECSE/EPOW-4080 Semiconductor Power
Electronics
• Pulses on Transmission Lines: ECSE-2100
Fields and Waves I
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