EE 370 Lab 4

MSI Implementation

Pre-lab: 12 pts

(For the circuit diagram for step 1, you will have to define your own symbol library with a definition of a 7493A, since that part is not in the eval.slb library provided by PSpice. To do this start up Schematics and then under the File Menu select Edit Library. This brings up the Symbol Editor window. Under the Parts Menu select Copy... In the resulting Copy Part window, click on Select Library and open the eval.slb library. From the list under Part: click on 93 and change the description in the New Part Name field to 7493A and then click OK. Now you can clean up the symbol definition by moving around some of the labels [and consider reducing the size of the characters used to name the input pins] to make the symbol more readable. Under the Part Menu select Attributes... and Definitions..., respectively, and fill in the appropriate values. [For example, Part and Model should both be 7493A.] When you are satisfied with your new symbol, under the File Menu select Save As... naming the result as your new symbol library. Then under the File Menu select Return to schematic to leave the Symbol Editor.)

All the circuit and state diagrams will be collected at the start of lab. Make a copy for your own use during lab.

In-lab:

1. IC Counter. Construct a 4-bit binary counter using a 7493. Connect R01 and R02 to logic low, QA to CKB, and QD, QC, QB, & QA to LEDs on the CADET. Vcc is pin 5 and GND is pin 10. Connect the clock input CKA to the CADET function generator. Set the frequency of the signal to 1 Hz or less and verify that the counter is counting correctly. Show your result to the instructor and have him initial this step.
   
   
   
   • Move the clock source from the function generator to one of the logic switches. Manually toggle the clock signal.
     
     
   • Does the counter still count correctly?
     
     
   • Why or why not? Explain. (Hint: see Wakerly pp. 587-590)
     
     
     
     
     
     
     
     
     
     
   • Connect the clock input to a debounced pushbutton switch for the remainder of the lab. Verify that you again have proper operation. Demonstrate this to the instructor and have him initial this step. Show the circuit you used to make this work:
     
     
     
     
     
     
     
     
     
     
2. IC Counter (cont.). The 7493 can be used to implement other count sequences by connecting counter outputs to the R0 inputs. The counter is reset to zero whenever both R0 inputs are 1s. Modify the counter to generate the sequence 0, 1, 2, 3, 4, 5, 0, 1, ... Show how you did this. Demonstrate this counter to the instructor and have him initial this step.
   
   
   
   
   
   
   
   
   
   
   
   
   
   
3. IC Shift Register. Experiment with the 74194 shift register until the behavior as defined by the function table of Wakerly Table 9-2 is understood.
   
   
   • Implement the ring counter shown in Wakerly Figure 9-43.
     
     
   • Demonstrate the counter to the instructor having him initial this step.
     
     
     
     1. Is the counter self-starting? (Self-starting is the same as self-correcting described in Wakerly 9.4.6)
        
        
     2. Why or why not? Explain.
        
        
        
        
        
        
        
        
        
4. Feedback shift register. Using a 74194 implement a feedback shift register whose feedback function is NextQA = QB XOR QD.
   • Show the instructor your result and have him initial this step.
     
     
   • Is the counter self-starting? Explain.