# DEM Lab 5 PAL's - Broome Community College by fjzhangxiaoquan

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```									                          Department of Electrical Engineering Technology
Broome Community College
Binghamton, New York

Digital Circuit Troubleshooting
Laboratory Exercise 5
Programmable Array Logic
Purpose:
The purpose of this exercise is to familiarize participants with programmable
array logic integrated circuits. A PAL16L8 will be programmed and then wired in a
circuit to verify the design specifications.

Equipment:
Digital Logic Designer
PAL Programmer
Personal Computer (with terminal emulation software)
Oscilloscope
Logic Analyzer
Integrated Circuits
7493         Binary Counter
PAL16L8      Programmable Logic Array

Procedure:

1)      Obtain the IC’s listed above. The PAL16L8 must be programmed before it will
function properly in the breadboard circuit. Your instructor will show you how to
use the PAL programmer to “burn a PAL.”

2)      After programming and verifying the PAL in the programmer place it and the
7493 into the breadboard. Make sure to place pin one of each IC toward the
lower left-hand corner of the breadboard.

3)      Wire the circuit according to the table on the next page. Note that the 7493 is a
14 pin IC, and the PAL is a 20 pin IC.

72d53a63-c9ef-4bb4-b3f7-9d6fc0e5f292.doc - 10/02/2012                   Donovan E. McCarty   1
Department of Electrical Engineering Technology
Broome Community College
Binghamton, New York

From                           To                              From                         To
7493 - 1                     7493 - 12                     PAL16L8 - 10                 Breadboard Ground
7493 - 2                   Breadboard S0                   PAL16L8 - 20                 Breadboard +5VDC
7493 - 3                   Breadboard S1
7493 - 5              Breadboard +5VDC
7493 - 8                 PAL16L8 - 3
7493 - 9                  PAL16L8 - 2
7493 - 10              Breadboard Ground
7493 - 11                    PAL16L8 - 4
7493 - 12                    PAL16L8 - 1
7493 - 14                  Breadboard Clock
+ 5 VDC                                                     + 5 VDC

5                                                        20
Vcc                                                          Vcc
14
Ck A         Qa
12                    D            1
I-0            O-0
19       / lf

7493                               C            2
I-1            O-1
18       / cr

2
R01          Qb
9                     B            3
I-2            O-2
17      / DD

3
R02                                      A            4
I-3            O-3
16      / CC

8                                  5                         15      / AA
Qc                                  NC        I-4            O-4
6                         14       / sp
NC        I-5            O-5
1                      11                                 7                         13       /I
Ck B         Qd                                  NC        I-6            O-6
GND                                            8                         12       /H
NC        I-7            O-7
10
9
NC        I-8
11         PAL16L8A
NC        I-9
GND
10

4)         Turn on the breadboard power and verify that a clock signal is present on pin 14
of the 7493 with the oscilloscope. If the signal is not present verify the circuit
connections and correct any wiring errors found. Ask your instructor for help if
you can not fix the problem.

5)         If there is a clock signal present on pin 14, check the four counter output signals
on pins 12, 11, 9, and 8 with the oscilloscope. These signals must be correct
before you proceed. Remember that pin 12 must be tied to pin 1, and the reset
pins can not both be high if the counter is expected to count.

72d53a63-c9ef-4bb4-b3f7-9d6fc0e5f292.doc - 10/02/2012                               Donovan E. McCarty   2
Department of Electrical Engineering Technology
Broome Community College
Binghamton, New York

6)      If the four counter outputs are correct, verify that the signals on pins 1, 2, 3, and 4
of the PAL are correct again using the oscilloscope. If not fix the problem.

7)      After successfully completing steps 1 through 6 you may now check the output
signals on the PAL. Use the oscilloscope to observe the signals on each of the
eight output pins of the. The outputs are on pins 12, 13, 14, 15, 16, 17,18, and 19.

8)      After observing each of the output signals turn off the breadboard. Connect the
logic analyzer leads according to the following table.

Logic Analyzer Lead                 Circuit Point
Ground                    Breadboard Ground
Black                         7493 - 12
Brown                          7493 - 9
Red                           7493 - 8
Orange                         7493 - 11
Yellow                       PAL16L8 - 12
Green                       PAL16L8 - 13
Blue                       PAL16L8 - 14
Violet                      PAL16L8 - 15

9)      Refer to the Laboratory Exercise 3 handout for setting the logic analyzer menus.
The logic analyzer information starts at step 17 on page 4.

10)     Turn on the breadboard power and start the analyzer. Observe the signals on the
analyzer. Compare each of the signals with the timing diagram provided. You
can use the cursor to help check the logic levels.

11)     After verifying the first four output signals turn off the breadboard power. Move
the four leads connected to the PAL to the new pins listed below. Leave the other
five leads connected as before.

Logic Analyzer Lead                   Circuit Point
Yellow                         PAL16L8 - 16
Green                         PAL16L8 - 17
Blue                        PAL16L8 - 18
Violet                      PAL16L8 - 19

72d53a63-c9ef-4bb4-b3f7-9d6fc0e5f292.doc - 10/02/2012                   Donovan E. McCarty   3
Department of Electrical Engineering Technology
Broome Community College
Binghamton, New York

12)     Turn on the breadboard power and start the logic analyzer. Observe the four new
signals on the analyzer and compare them with the timing diagram.

PART 2 - VIEWING THE WAVEFORMS USING HYPERTERM

Build the TTL to RS232C converter circuit shown below. Be careful not to
connect any of this to the logic analyzer - since there's a negative voltage
involved you could seriously damage the logic analyzer. So - oscilloscope
only.

Verify that you have an RS232C waveform ready before connecting to the
computer. The RS232C waveform should be a +/- 5 volt waveform. An image of
this should be included with your report.

Connect the USB to Serial adapter to your computer, bring up Hyperterm, set to
2400 Baud, 7N1 for data. Adjust the clock rate to the 7493 binary counter to
match the 2400 setting.

One at a time, observe the converted PAL outputs on the Hyperterm screen. Take
a screen shot of several of the output characters.

13)     Turn off the breadboard power. Remove the analyzer leads from the circuit.
Disassemble the circuit. Return the IC’s. Place the PAL in protective foam.

72d53a63-c9ef-4bb4-b3f7-9d6fc0e5f292.doc - 10/02/2012                   Donovan E. McCarty   4

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