CS122A
Fall Quarter, 1999

Lab 7 -- VHDL: Designing A Calculator And Downloading It Onto An XS40 Board
Prof. Frank Vahid

Purpose
The purpose of this lab is to implement a finite state machine in VHDL to perform simple calculations like addition, subtraction, and multiplication. Write a testbench to check it's functionality. Then download it onto an XS40 board using DIP switches to vary the inputs.

Assignment
In this lab:

• Design a calculator using VHDL. It should take in 3 inputs
  • 2  4-bit operands
  • 1  2-bit operator (i.e. 00 is addition, 01 is subtraction, ...)
• Check it's functionality using ALDEC VHDL simulator
• Wire up the DIP switch to the XS40 board
• Download your program unto XS40 board and test your program

Apparatus Required:

1. 10 pin DIP Switch
2. XS40 Board

Schematic:




Program:

--
-- Tony Givargis
--

--********************************************************************

library IEEE;
use IEEE.STD_LOGIC_1164.all;
use IEEE.STD_LOGIC_ARITH.all;

--********************************************************************

entity XS40 is
   port (rst: in STD_LOGIC;
         clk: in STD_LOGIC;

         --define operands and operator here

         led: out UNSIGNED(6 downto 0));
end XS40;

--********************************************************************

architecture XS40_ARCH of XS40 is

   component WRLED
      port(val: in UNSIGNED(3 downto 0);
           led: out UNSIGNED(6 downto 0));
   end component;

   signal val:UNSIGNED(3 downto 0);

begin

   U1:WRLED port map(val, led);

   process(rst, clk, ...)

   -- insert calculator code here

   end process;
end XS40_ARCH;
   

Steps to be followed:

1. Complete the code and test the functionality using ALDEC VHDL. Show TA the waveforms.
2. Complete the wrled.vhd code. You may find the 7-segment display diagram useful.
3. Run through the tutorial and see if you can get the XS40 board to count.
   (Note: Jumper on J4 needs to be set when loading program but disconnected when running program)
4. Wire up the circuit. You may need the circuit diagram or the XS40 board manual.
5. Make the necessary additions to your tut1.ucf file.
6. Download your program unto the XS40 board and test your program.

Conclusion:
Show the TA the waveforms from the ALDEC VHDL simulation and demonstrate your implementations on the XS40 board to the TA.

Please include your VHDL source files while turning in the report.