Lab 4 - EE-313 VECTORS AND MORE
Rev 01/30/2013
I.
Purpose:
A. Reinforce the skill necessary to implement a functional logic design.
B. Introduce VECTOR data types and the WITH/SELECT/WHEN and WHEN/ELSE
statements.
II.
Equipment:
A. Computer with Altera Software and web access
B. Altera DE2 Board with power supply and USB cable
III.
Pre-lab assignment:
A. Complete BCD to 7 Segment Display Driver Design and record equations in your lab
notebook.
IV.
Lab Procedure and Questions:
In this project, you will create a BCD to 7 segment display driver using VHDL and then test it
using by incorporating it into a test schematic. The project must meet the following design
requirements.
BCD to Seven Segment Display Driver Requirements
PROJECT NAME: yourlastname_lab04
ENTITY NAME yourlastname_bcd2seven
FUNCTION Drive an active high seven segment display given a 4 bit BCD number.
NAME
TYPE
SIZE
STD_LOGIC_VECTOR
4 Bits
INPUT x
STD_LOGIC
1 Bit Each
OUTPUTS a,b,c,d,e,f,g
ENTITY NAME yourlastname_lab04
FUNCTION Connect your bcd2seven entity to sw[3] through sw[0] and display the
corresponding decimal value on one of the ALTERA boards 7 segment
displays.
NAME
TYPE
SIZE
Input pin
INPUT sw[3 downto 0]
OUTPUTS ledr[3 downto 0] Output pins
hex0[7 downto 0] Output pins
NOTES Output pins hex0[7 downto 0] should be connected to the corresponding
outputs of the BCD 2 Seven Segment Display Driver.
The LEDs of the seven segment displays are Active LOW.
Design Segment Labels
DE2 Segment Labels
Lab 4 - EE-313 VECTORS AND MORE
Rev 01/30/2013
A New Datatype
STD_LOGIC_VECTOR
The STD_LOGIC_VECTOR expands the STD_LOGIC datatype so that bits can be grouped
together in a meaningful way. Line 6 of the sample code illustrates how to define an input
variable of type STD_LOGIC_VECTOR. This definition prevents having to define 4 separate
input ports x3, x2, x1, and x0. Additionally, it allows VHDL to treat the signal as a complete
unit thus allowing statements like that shown on Line 15.
If you want to access the individual elements of the STD_LOGIC VECTOR, you can simply by
referencing the desired bit as shown on Line 23 of the sample code.
Two New Statements
The WHEN/ELSE and WITH/SELECT/WHEN statements allow you to specify your logic in a
format similar to a truth table. Each essentially assigns a value to the target when a particular
condition exists. Line 15 of the sample code is one example of how to use the WHEN/ELSE
statement. Lines 18 through 21 show an example of the WITH/SELECT/WHEN statement.
WHEN/ELSE Statement
Syntax:
The conditions in a WHEN/ELSE statement are prioritized. The first output statement listed has
the highest priority and will be executed first, if the condition is true. If the first condition is not
true, the second output statement will be executed next, and so on.
WITH/SELECT/WHEN Statement
Syntax:
Commas are used in a
WITH/SELECT/WHEN
statement
WHEN OTHERS must be used to
terminate a WITH/SELECT/WHEN
The selected signal assignment (WITH/SELECT/WHEN) examines the value of the expression
and executes only the assignment statement that matches the WHEN value, and all other
statements are skipped.
WHEN OTHERS is required to terminate a WITH/SELECT/WHEN statement. This is used to
ensure that all possible choices of the expression are considered.
Note the use of commas in the syntax for the WITH/SELECT/WHEN statement.
Lab 4 - EE-313 VECTORS AND MORE
Rev 01/30/2013
Figure 1 – Sample Code
A. Create a new project
B. Implement the bcd2seven entity such that it meets the design requirements using the
Sample Code as a starting point. In order to implement outputs d through g, you can use any
of the three methods shown.
Note: You can check for syntax errors while you go by selecting
Processing→Analyze Current File.
C. Create a Symbol File for your new entity.
D. Implement the lab04 top level entity using a block diagram/schematic such that it meets
the design requirements.
NOTE: When assigning the input pin to your device, only one pin is required. It should
be named sw[3..0] and it should be connected to input x using the Orthogonal Bus Tool.
E. Program your Altera board and demonstrate its proper performance to the Instructor.
F. Include a print out of your bcd2seven entity from the RTL Viewer in your lab notebook.
G. Questions
1.
2.
3.
4.
What questions did you ask the instructor while performing this lab?
What were the answers to the questions asked?
What character is displayed on your 7 segment display when X=”1111”?
Identify the order of execution for your code if any.