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


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

                         Digital Circuit Troubleshooting
                                 Laboratory Exercise 5
                               Programmable Array Logic
         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.

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


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
         Ck A         Qa
                            12                    D            1
                                                                    I-0            O-0
                                                                                         19       / lf

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

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

         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
                                                          NC        I-8
                                                               11         PAL16L8A
                                                          NC        I-9

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.


        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

        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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