Introduction to Engineering Electronics

1
Lecture 5

• Binary Counter
• Thinking Digitally

2
Henry Farnys Song of the Talking Wire
3
2 Minute QuizName_________________
Sec____

• Code Example
• Code Example
• Code Example
• PWM Question

4
Joseph Henry the Telegraph

• Albany Academy Experiment
• Assisted Morse at Princeton
• 1st Head of Smithsonian
• Unit of inductance Henry

5
Morse Code

• Simple sequences of short and long clicks to
  represent letters and numbers
• Easier to generate than sound
• Easier to distinguish than sound

6
UPC Codes

• Bars come in four widths 1-2-3-4
• Start is 1-1-1 (black-white-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

• 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-bar-space-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).

7
Computer Number System ExamplesFrom Computer
Science I
10110101110001011001110011110110 binary number
11 5 12 5 9 12 15 6

equivalent base 10 value for each group of 4
consecutive binary digits (bits)
B 5 C 5 9 C F
6
corresponding hexadecimal (base 16) digit
B5C59CF6
equivalent hexadecimal number
8
Communicating With Pulses

• PCM Pulse Code Modulation

9
PCM Pulse Code Modulation
10
PWM Pulse Width Modulation

• Signal is compared to a sawtooth wave producing a
  pulse width proportional to amplitude

11
Optical Receiver

• Receiver detects pulses of light
• Pulses are amplified and partly averaged by 741
  op-amp (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

12
Optical Transmitter

• Audio signal changes thresholds for 555 timer
  producing a type of pulse width modulation of the
  light from the LED.

13
Signals from Audio Remote
Mostly hear higher frequencies in pulses
3.5 x 20 70ms or 14Hz
2 x 100 / 9 23us or 43kHz
4 x 500 2000us or 500Hz
14
Binary Numbers

• 6 0110
• 7 0111
• 8 1000
• 9 1001
• 10 1010
• 11 1011

0 0000 1 0001 2 0010 3 0011 4 0100 5 0101
128 0 32 16 0
4 2 1 183
15
Binary Counter

• Animations showing counter operation
• http//www.play-hookey.com/digital/synchronous_c
  ounter.html
• Counter for lab

16
Typical Output for Binary Counter

• Note how the Q outputs form 4 bit numbers

17
Digital Pulses

• Function generator produces a 1kHz sinusoidal
  voltage. 1v peak-to-peak (pp)

18
Digital Pulses

• Switch to a square wave at 1kHz. Still 1v pp

19
Digital Pulses

• Add a 0.5 volt offset so that the square wave
  goes from 0 volts to 1 volt

20
Digital Pulses

• Now the duty cycle is adjusted to 20 to see what
  a single digital pulse looks like.

21
Pulses on a Transmission Line
From Matlab

• 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.

22
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)
• Answer The longer the duty cycle, the longer the
  light bulb is on and the brighter the light.

23
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

24
What About Analog Modulation?

• AM Amplitude Modulation
• FM Frequency Modulation

25
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

26
Image Compression
2 bpp
0.5 bpp
24 bpp original (bits per pixel)
Top JPEG Bottom JPEG2K
27
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