Welcome to ProgrammingHomeworkHelp.com, your go-to destination for mastering VHDL (VHSIC Hardware Description Language). If you're struggling with VHDL assignments and find yourself thinking, "write my VHDL assignment," then you're in the right place. In this post, we'll delve into some master-level VHDL questions along with expert solutions crafted by our seasoned professionals. Whether you're a novice or an advanced learner, these solutions will help you grasp VHDL concepts more effectively.

Question 1: Designing a Finite State Machine (FSM)

Given the following requirements, design a Finite State Machine (FSM) using VHDL:

- The FSM should detect a specific sequence '1010' in an input stream.
- Output '1' should be asserted when the sequence is detected; otherwise, output '0'.
- Assume asynchronous inputs and synchronous outputs.

Solution:

```vhdl
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

entity FSM_Detector is
Port ( clk : in STD_LOGIC;
reset : in STD_LOGIC;
input_bit : in STD_LOGIC;
output_detected : out STD_LOGIC);
end FSM_Detector;

architecture Behavioral of FSM_Detector is
type state_type is (S0, S1, S2, S3, S4);
signal current_state, next_state : state_type;
begin
process(clk, reset)
begin
if reset = '1' then
current_state <= S0;
elsif rising_edge(clk) then
current_state <= next_state;
end if;
end process;

process(current_state, input_bit)
begin
case current_state is
when S0 =>
if input_bit = '1' then
next_state <= S1;
else
next_state <= S0;
end if;
when S1 =>
if input_bit = '0' then
next_state <= S2;
else
next_state <= S0;
end if;
when S2 =>
if input_bit = '1' then
next_state <= S3;
else
next_state <= S0;
end if;
when S3 =>
if input_bit = '0' then
next_state <= S4;
else
next_state <= S0;
end if;
when S4 =>
if input_bit = '1' then
output_detected <= '1';
next_state <= S0;
else
next_state <= S0;
end if;
end case;
end process;
end Behavioral;
```

Question 2: Implementing a UART Transmitter

You are tasked with designing a UART (Universal Asynchronous Receiver/Transmitter) transmitter module in VHDL. The module should have the following specifications:

- Baud rate: 9600 bps
- 8-bit data, 1 start bit, 1 stop bit, no parity
- Assume a 50 MHz clock input

Solution:

```vhdl
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL;

entity UART_Transmitter is
Port ( clk : in STD_LOGIC;
reset : in STD_LOGIC;
data_in : in STD_LOGIC_VECTOR(7 downto 0);
tx : out STD_LOGIC);
end UART_Transmitter;

architecture Behavioral of UART_Transmitter is
constant BAUD_RATE : integer := 9600;
constant CLOCK_FREQ : integer := 50000000;
signal counter : integer range 0 to (CLOCK_FREQ / BAUD_RATE / 2) - 1 := 0;
signal bit_counter : integer range 0 to 10 := 0; -- 8 data bits + 1 start bit + 1 stop bit
signal transmit_reg : std_logic_vector(9 downto 0) := (others => '1'); -- Start bit
begin
process(clk, reset)
begin
if reset = '1' then
counter <= 0;
bit_counter <= 0;
tx <= '1'; -- Idle state
elsif rising_edge(clk) then
if counter = 0 then
if bit_counter < 10 then
tx <= transmit_reg(bit_counter);
bit_counter <= bit_counter + 1;
else
bit_counter <= 0;
end if;
end if;

counter <= counter + 1;
if counter = (CLOCK_FREQ / BAUD_RATE / 2) - 1 then
counter <= 0;
end if;
end if;
end process;

process(clk)
begin
if rising_edge(clk) then
if reset = '1' then
transmit_reg <= (others => '1'); -- Reset start bit
elsif bit_counter = 0 then
transmit_reg <= '0' & data_in & '1'; -- Start bit + Data + Stop bit
end if;
end if;
end process;
end Behavioral;
```

Conclusion

These solutions demonstrate the power and versatility of VHDL in solving complex digital design problems. Whether it's designing Finite State Machines or implementing communication protocols like UART, VHDL provides the flexibility and precision required for hardware description. We hope these solutions have provided valuable insights into VHDL programming and assist you in mastering this essential skill. If you need further assistance or have any questions, don't hesitate to reach out to us at ProgrammingHomeworkHelp.com. Happy coding!