Concurrent signal assignment in VHDL - Mini Project: Build & Apply

Concurrent Signal Assignment in VHDL

📖 Scenario: You are designing a simple digital circuit that controls two LEDs based on two input switches. You want to assign the LED signals concurrently so that they update immediately when the switches change.

🎯 Goal: Build a VHDL design that uses concurrent signal assignment statements to control two LEDs from two switches.

📋 What You'll Learn

Create signals for two switches and two LEDs

Assign LED signals concurrently based on switch signals

Use simple concurrent signal assignment statements

Print the final LED signal values in simulation

💡 Why This Matters

🌍 Real World

Concurrent signal assignment is used in digital hardware design to update outputs immediately based on inputs, such as controlling LEDs, motors, or other devices.

💼 Career

Understanding concurrent signal assignment is essential for FPGA and ASIC designers who write VHDL code to implement hardware logic.

1

Create input and output signals

Create two signals called switch1 and switch2 of type std_logic and initialize both to '0'. Also create two signals called led1 and led2 of type std_logic.

VHDL

-- Declare signals for switches and LEDs
-- Your code here

Need a hint?

Signals are declared with the keyword signal. Initialize switch1 and switch2 to '0'.

2

Set switch1 to '1' to simulate pressing the switch

Assign the value '1' to the signal switch1 to simulate pressing the first switch.

VHDL

signal switch1 : std_logic := '0';
signal switch2 : std_logic := '0';
signal led1 : std_logic;
signal led2 : std_logic;

-- Set switch1 to '1'
-- Your code here

Need a hint?

Change the initialization of switch1 to '1'.

3

Assign LEDs concurrently based on switches

Use concurrent signal assignment statements to assign led1 the value of switch1 and led2 the value of switch2.

VHDL

signal switch1 : std_logic := '1';
signal switch2 : std_logic := '0';
signal led1 : std_logic;
signal led2 : std_logic;

-- Assign led1 and led2 concurrently
-- Your code here

Need a hint?

Use the <= operator for concurrent signal assignment outside processes.

4

Print the LED values in simulation

Write a process that prints the values of led1 and led2 using report statements to show the LED states.

VHDL

signal switch1 : std_logic := '1';
signal switch2 : std_logic := '0';
signal led1 : std_logic;
signal led2 : std_logic;

led1 <= switch1;
led2 <= switch2;

-- Add a process to print LED values
-- Your code here

Need a hint?

Use a process with a wait statement and a report to display signal values in simulation.