ECE241F - Digital Systems

1.0 Purpose

The purpose of this lab is to build several more complex logic circuits and to gain increased familiarity with the Quartus II 3.0 CAD software.

2.0 Background

A seven-segment display is often used on computers, watches, DVD players and many electronic devices to display numbers and some characters. It consists of seven independent lights (actually light-emitting diodes (LEDs)) in an “8” configuration as shown below in Figure 1 on page 3. By turning on different segments, you can display different numbers and some letters.

3.0 Preparation

You are to create two logic circuits to drive one of the seven-segment displays on the Altera programmable logic board. Please see Section 5.0 for details of how to use these boards. (In particular, note that to turn a light-segment on, you must drive the corresponding pin to a logical “0”).

Your preparation, to be marked, should consist of the Verilog code and the simulator output for all circuits. Be sure to print out the simulation results and Verilog code for marking, and paste it in your lab book.

1. Design a circuit that takes a four bit (X3, X2, X1, X0) input from the digital switch board (like you did in Lab #2) and drives digit #1 on the Altera board as described in the table below. Note that for the letters, some are capitalized and some are not. (The reason is that a capital B, for example, would come out the same as an 8 on a 7- segment display, so we will display a lower-case b instead).

X3 X2 X1X0	Display (note the capitalization)
0000	0
0001	1
0010	2
0011	3
0100	4
0101	5
0110	6
0111	7
1000	8
1001	9
1010	A
1011	b
1100	C
1101	d
1110	E
1111	F

Determine the equations for the 7-segment display segments, and minimize them using the Karnaugh-map method described in class. Write Verilog code to represent the logic function for each segment as a boolean equation (with AND, OR, NOT, etc.). Simulate and test your equations using the Quartus functional simulator, or with the timing simulator with the MAX 7128S device set.

2. Design a similar circuit to the one given in part 1, except that you should use the four input switches to generate the letters of your last name. For example, if your last name is Parnas, you could use code 0000 to display an P, 0001 to display an A, 0010 to display a R (or something as close to a R as you can get). Note that you can choose any code you wish for each letter. Notice also that you don’t need to create two codes for a letter that appears twice in your name. For example, the letter A appears twice in Parnas, but you only need to produce one code for the letter A - the intent is that you will be able to spell out your last name on the 7-segment display by entering the codes for the letters one at a time.

For Fairness: if your last name is longer than 9 unique letters, you need only do 9 unique characters of it. If your last name is shorter than 9 characters, you must add more letters from your first name until you have coded at least 9 unique characters.

Since you will only need to do 9 codes, you can leverage the don’t cares that will be available in the truth tables.

1. First, check and make sure that the 7-segment display and Altera board are working, by copying the file ~jayar/ece241/lab3/flash.pof (on the ECE ugsparc system) and place it into a separate directory. (You can use this in all succeeding labs as a quick hardware test).

Then, open a new project (call it flash) in Quartus the Programmer module by selecting Tools | Programmer, and then select the file flash.pof from your directory using the Edit|Add File command. You can then download this circuit into the device in the same way you did in lab #2. The cicuit will count upwards using the 7-segment displays.

5.0 Connections Between MAX 7128 and The Seven-Segment Decoder

The Altera programmable logic board has two seven segment displays attached directly to the pins of the chip. The figure below shows the naming of each segment. The subsequent table gives the connections between segments and the MAX 7128 pins. NOTE: to turn a segment on, you must drive the associated pin with a “0.” (not a 1).

Display Segment	7128 Pin for Digit 1	7128 Pin for Digit 2
a	58	69
b	60	70
c	61	73
d	63	74
e	64	76
f	65	75
g	67	77
Decimal point	68	79