Science @kbin.social dejo @kbin.social 1y ago

Hi, I'm not quite sure if this vhdl code and testbench is correct for the given task. Can you take a look?

Design a one-hour kitchen timer. The device should have buttons/switches to start and stop the timer, as well as to set the desired time interval for the alarm. Realize the task using the software package Quartus or in GHDL, confirm the correctness of the project task by simulation.

This is VHDL code:

use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

entity Kitchen_Timer is
  port (
    clk   : in std_logic;    -- Clock input
    reset : in std_logic;    -- Reset input
    start : in std_logic;    -- Start button input
    stop  : in std_logic;    -- Stop button input
    alarm : out std_logic    -- Alarm output
  );
end entity Kitchen_Timer;

-- Declare the architecture for the kitchen timer
architecture Behavioral of Kitchen_Timer is
  signal count     : integer range 0 to 3600 := 0;   -- Counter for timer
  signal alarming  : std_logic := '0';               -- Signal to indicate alarming interval
  signal alarm_en  : std_logic := '0';               -- Signal to enable alarming interval
  signal alarm_cnt : integer range 0 to 600 := 0;    -- Counter for alarming interval
begin
  -- Process to control the kitchen timer and alarming interval
  process (clk, reset)
  begin
    if (reset = '1') then
      count     <= 0;
      alarming  <= '0';
      alarm_en  <= '0';
      alarm_cnt <= 0;
    elsif (rising_edge(clk)) then
      if (stop = '1') then
        count     <= 0;
        alarming  <= '0';
        alarm_en  <= '0';
        alarm_cnt <= 0;
      elsif (start = '1' and count < 3600) then
        count <= count + 1;
        if (count = 3600) then
          count     <= 0;
          alarming  <= '0';
          alarm_en  <= '0';
          alarm_cnt <= 0;
        elsif (count > 0) then
          alarm_en <= '1';
        end if;
      end if;

      if (alarm_en = '1') then
        if (alarm_cnt < 600) then
          alarm_cnt <= alarm_cnt + 1;
        else
          alarm_cnt <= 0;
          alarming  <= '1';
        end if;
      end if;
    end if;
  end process;

  -- Assign the alarm output
  alarm <= alarming;
end architecture Behavioral; ```

This is Testbench:

```library ieee;
use ieee.std_logic_1164.all;

entity tb_Kitchen_Timer is
end tb_Kitchen_Timer;

architecture tb of tb_Kitchen_Timer is

    component Kitchen_Timer
        port (clk   : in std_logic;
              reset : in std_logic;
              start : in std_logic;
              stop  : in std_logic;
              alarm : out std_logic);
    end component;

    signal clk   : std_logic;
    signal reset : std_logic;
    signal start : std_logic;
    signal stop  : std_logic;
    signal alarm : std_logic;

    constant TbPeriod : time := 1000 ns; -- EDIT Put right period here
    signal TbClock : std_logic := '0';
    signal TbSimEnded : std_logic := '0';

begin

    dut : Kitchen_Timer
    port map (clk   => clk,
              reset => reset,
              start => start,
              stop  => stop,
              alarm => alarm);

    -- Clock generation
    TbClock <= not TbClock after TbPeriod/2 when TbSimEnded /= '1' else '0';

    -- EDIT: Check that clk is really your main clock signal
    clk <= TbClock;

    stimuli : process
    begin
        -- EDIT Adapt initialization as needed
        start <= '0';
        stop <= '0';

        -- Reset generation
        -- EDIT: Check that reset is really your reset signal
        reset <= '1';
        wait for 100 ns;
        reset <= '0';
        wait for 100 ns;

        -- EDIT Add stimuli here
        wait for 100 * TbPeriod;

        -- Stop the clock and hence terminate the simulation
        TbSimEnded <= '1';
        wait;
    end process;

end tb;

-- Configuration block below is required by some simulators. Usually no need to edit.

configuration cfg_tb_Kitchen_Timer of tb_Kitchen_Timer is
    for tb
    end for;
end cfg_tb_Kitchen_Timer;```

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21 comments

@T4V0 Hello, I've been doing a lot of research on this project these days and I've brought the code to a better level, I hope... But I'm not sure if this simulation...

This is VHDL code:
library ieee;

use ieee.std_logic_1164.all;

use ieee.numeric_std.all;

entity Kitchen_Timer is

port (

clk : in std_logic; -- Clock input

reset : in std_logic; -- Reset input

start : in std_logic; -- Start button input

stop : in std_logic; -- Stop button input

adjust_interval_up : in std_logic; -- Button for increasing alarm interval

adjust_interval_down : in std_logic; -- Button for decreasing alarm interval

alarm : out std_logic -- Alarm output

);

end entity Kitchen_Timer;

architecture Behavioral of Kitchen_Timer is

signal count : integer range 0 to 3600000 := 0; -- Adjust range for 1 hour

signal alarming : std_logic := '0';

signal alarm_interval : integer range 600 to 3600000 := 600; -- Adjust range for 1 hour

begin

process (clk, reset)

begin

if reset = '1' then

count <= 0;

alarming <= '0';

alarm_interval <= 600;

elsif rising_edge(clk) then

if start = '1' then

count <= count + 1;

end if;

if stop = '1' or count = alarm_interval then

count <= 0;

end if;

if adjust_interval_up = '1' then

if alarm_interval < 3600000 then

alarm_interval <= alarm_interval + 600; -- Adjust increment for 1 minute

end if;

elsif adjust_interval_down = '1' then

if alarm_interval > 600 then

alarm_interval <= alarm_interval - 600; -- Adjust decrement for 1 minute

end if;

end if;

end if;

end process;

alarming <= '1' when count >= alarm_interval else '0';

alarm <= alarming;

end architecture Behavioral;

This is Testbench:
library ieee;

use ieee.std_logic_1164.all;

entity tb_Kitchen_Timer is

end tb_Kitchen_Timer;

architecture tb of tb_Kitchen_Timer is

component Kitchen_Timer

port (

clk : in std_logic;

reset : in std_logic;

start : in std_logic;

stop : in std_logic;

adjust_interval_up : in std_logic;

adjust_interval_down : in std_logic;

alarm : out std_logic

);

end component;

signal clk : std_logic := '0';

signal reset : std_logic := '0';

signal start : std_logic := '0';

signal stop : std_logic := '0';

signal adjust_interval_up : std_logic := '0';

signal adjust_interval_down : std_logic := '0';

signal alarm : std_logic;

constant TbPeriod : time := 1 us; -- Set the clock period to 1us

signal TbClock : std_logic := '0';

signal TbSimEnded : std_logic := '0';

begin

dut : Kitchen_Timer

port map (

clk => clk,

reset => reset,

start => start,

stop => stop,

adjust_interval_up => adjust_interval_up,

adjust_interval_down => adjust_interval_down,

alarm => alarm

);

-- Clock generation

TbClock <= not TbClock after TbPeriod/2 when TbSimEnded /= '1' else '0';

clk <= TbClock;

stimuli : process

begin

-- Reset generation

reset <= '1';

wait for 20 us; -- Adjust delay to fit the new clock period

reset <= '0';

-- Add your stimuli and test cases here

-- For example:

start <= '1';

wait for 50 us; -- Adjust delay to fit the new clock period

start <= '0';

wait for 400 us; -- Adjust delay to fit the new clock period

adjust_interval_up <= '1';

wait for 20 us; -- Adjust delay to fit the new clock period

adjust_interval_up <= '0';

wait for 50 us; -- Adjust delay to fit the new clock period

adjust_interval_down <= '1';

wait for 20 us; -- Adjust delay to fit the new clock period

adjust_interval_down <= '0';

wait for 50 us; -- Adjust delay to fit the new clock period

-- ...

-- Stop the clock and hence terminate the simulation

TbSimEnded <= '1';

wait;

end process;

end tb;

-- Configuration block below is required by some simulators. Usually no need to edit.

configuration cfg_tb_Kitchen_Timer of tb_Kitchen_Timer is

for tb

end for;

end cfg_tb_Kitchen_Timer;
And this is result of simulation:
- @dejo This is much better, but there is still some room for improvement.
  
  There is a mismatch between your comparisons count and alarm_interval. Here in the code bellow you can see the issue:
  
  if stop = '1' or count = alarm_interval then count <= 0; -- count is 0 here end if; [...] alarming <= '1' when count >= alarm_interval else '0'; -- This condition is never true due to count always being 0 or smaller the alarm_interval. alarm <= alarming;
  
  As it is right now, the alarming signal is never going to be '1'. It is best to split the comparison and write to alarming directly:
  
  if stop = '1' then count <= 0; alarming <= '0'; end if; if count = alarm_interval then alarming <= '1'; end if; [...] alarm <= alarming;
  
  As for the testbench, you should set the start and unset it only after the alarming is '1', and test if alarming is working after adjusting the timer:
  
  stimuli : process begin -- Reset generation reset <= '1'; wait for 20 us; -- Adjust delay to fit the new clock period reset <= '0'; -- Add your stimuli and test cases here -- For example: start <= '1'; stop <= '0'; wait for 620 us; -- Wait until alarm is alarming start <= '0' stop <= '1'; adjust_interval_up <= '1'; wait for 1 us; -- Increment the timer by a minute start <= '1'; stop <= '0'; adjust_interval_up <= '0'; wait for 1220 us; -- Wait until the alarm is alarming start <= '0'; stop <= '1'; adjust_interval_down <= '1'; wait for 1 us; -- Decrement the timer by a minute start <= '1'; stop <= '0'; adjust_interval_down <= '0'; wait for 620 us; -- Wait until the alarm is alarming start <= '0'; stop <= '1'; wait for 20 us; -- ... -- Stop the clock and hence terminate the simulation TbSimEnded <= '1'; wait; end process;
  
  I suggest changing the 100 ms time slices you use in the timer to a minute instead. That way your simulation time could be much quicker (though you would also have to change the testbench delays).
  
  @T4V0 I
  In the meantime, I worked on improving the code.
  
  VHDL code:
  llibrary ieee;
  use ieee.std_logic_1164.all;
  use ieee.numeric_std.all;
  
  entity Kitchen_Timer is
  port (
  clk : in std_logic; -- Clock input
  reset : in std_logic; -- Reset input
  start : in std_logic; -- Start button input
  stop : in std_logic; -- Stop button input
  adjust_interval_up : in std_logic; -- Button for increasing alarm interval
  adjust_interval_down : in std_logic; -- Button for decreasing alarm interval
  alarm : out std_logic -- Alarm output
  );
  end entity Kitchen_Timer;
  architecture Behavioral of Kitchen_Timer is
  signal count : integer range 0 to 3600000 := 0; -- Adjust range for 1 hour
  signal alarming : std_logic := '0';
  signal alarm_interval : integer range 600 to 3600000 := 600; -- Adjust range for 1 hour
  begin
  process (clk, reset)
  begin
  if reset = '1' then
  count <= 0;
  alarm_interval <= 600;
  elsif rising_edge(clk) then
  if start = '1' then
  count <= count + 1;
  end if;
  if stop = '1' or count = alarm_interval then
  count <= 0;
  end if;
  if adjust_interval_up = '1' then
  if alarm_interval < 3600000 then
  alarm_interval <= alarm_interval + 600; -- Adjust increment for 1 minute
  end if;
  count <= 0; -- Reset count when adjusting interval
  elsif adjust_interval_down = '1' then
  if alarm_interval > 600 then
  alarm_interval <= alarm_interval - 600; -- Adjust decrement for 1 minute
  end if;
  count <= 0; -- Reset count when adjusting interval
  end if;
  end if;
  end process;
  alarming <= '1' when count >= alarm_interval else '0';
  alarm <= alarming;
  end architecture Behavioral;
  
  Testbench:
  
  library ieee;
  use ieee.std_logic_1164.all;
  
  entity tb_Kitchen_Timer is
  end tb_Kitchen_Timer;
  architecture tb of tb_Kitchen_Timer is
  component Kitchen_Timer
  port (
  clk : in std_logic;
  reset : in std_logic;
  start : in std_logic;
  stop : in std_logic;
  adjust_interval_up : in std_logic;
  adjust_interval_down : in std_logic;
  alarm : out std_logic
  );
  end component;
  signal clk : std_logic := '0';
  signal reset : std_logic := '0';
  signal start : std_logic := '0';
  signal stop : std_logic := '0';
  signal adjust_interval_up : std_logic := '0';
  signal adjust_interval_down : std_logic := '0';
  signal alarm : std_logic;
  constant TbPeriod : time := 20 ns;
  signal TbClock : std_logic := '0';
  signal TbSimEnded : std_logic := '0';
  begin
  dut : Kitchen_Timer
  port map (
  clk => clk,
  reset => reset,
  start => start,
  stop => stop,
  adjust_interval_up => adjust_interval_up,
  adjust_interval_down => adjust_interval_down,
  alarm => alarm
  );
  -- Clock generation
  TbClock <= not TbClock after TbPeriod/2 when TbSimEnded /= '1' else '0';
  clk <= TbClock;
  stimuli : process
  variable num_ticks : natural;
  begin
  -- Reset generation
  reset <= '1';
  wait for 200 us;
  reset <= '0';
  wait for 200 us;
  -- Start the timer
  start <= '1';
  wait for 500 us;
  -- Adjust interval up and down
  adjust_interval_up <= '1';
  wait for 100 us;
  adjust_interval_up <= '0';
  wait for 100 us;
  adjust_interval_down <= '1';
  wait for 100 us;
  adjust_interval_down <= '0';
  wait for 100 us;
  -- Wait for the timer to reach the alarm interval (3600000 clocks)
  wait for 72 ms; -- Simulate for the required time
  -- Stop the timer
  start <= '0';
  wait for 300 us;
  -- Stop the clock and terminate the simulation
  TbSimEnded <= '1';
  wait;
  end process;
  end tb;
  
  And this is simulation:
  
  @dejo I have made a few changes to your code:
  
  Kitchen_Timer.vhd
  
  library ieee; use ieee.std_logic_1164.all; use ieee.numeric_std.all; entity Kitchen_Timer is port ( clk : in std_logic; -- Clock input reset : in std_logic; -- Reset input start : in std_logic; -- Start button input stop : in std_logic; -- Stop button input adjust_interval_up : in std_logic; -- Button for increasing alarm interval adjust_interval_down : in std_logic; -- Button for decreasing alarm interval alarm : out std_logic -- Alarm output ); end entity Kitchen_Timer; architecture Behavioral of Kitchen_Timer is signal count : integer range 0 to 60 := 0; -- Adjust range for 1 hour signal alarming : std_logic := '0'; signal alarm_interval : integer range 1 to 60 := 1; -- Adjust range for 1 hour begin process (clk, reset) begin if reset = '1' then count <= 0; alarm_interval <= 1; elsif rising_edge(clk) then if start = '1' then count <= count + 1; end if; if stop = '1' then count <= 0; alarming <= '0'; end if; if count = alarm_interval then alarming <= '1'; end if; if adjust_interval_up = '1' then if alarm_interval < 60 then alarm_interval <= alarm_interval + 1; -- Adjust increment for 1 minute end if; count <= 0; -- Reset count when adjusting interval elsif adjust_interval_down = '1' then if alarm_interval > 60 then alarm_interval <= alarm_interval - 1; -- Adjust decrement for 1 minute end if; count <= 0; -- Reset count when adjusting interval end if; end if; end process; alarm <= alarming; end architecture Behavioral;
  
  tb_Kitchen_Timer.vhd
  
  library ieee; use ieee.std_logic_1164.all; use ieee.numeric_std.all; entity tb_Kitchen_Timer is end tb_Kitchen_Timer; architecture tb of tb_Kitchen_Timer is signal clk : std_logic := '0'; signal reset : std_logic := '0'; signal start : std_logic := '0'; signal stop : std_logic := '0'; signal adjust_interval_up : std_logic := '0'; signal adjust_interval_down : std_logic := '0'; signal alarm : std_logic; constant TbPeriod : time := 10 ns; signal TbClock : std_logic := '0'; signal TbSimEnded : std_logic := '0'; begin dut : entity work.Kitchen_Timer port map ( clk => clk, reset => reset, start => start, stop => stop, adjust_interval_up => adjust_interval_up, adjust_interval_down => adjust_interval_down, alarm => alarm ); -- Clock generation TbClock <= not TbClock after TbPeriod/2 when TbSimEnded /= '1' else '0'; -- EDIT: Check that clk is really your main clock signal clk <= TbClock; stimuli : process variable num_ticks : natural; begin -- Reset generation reset <= '1'; wait for 20 ns; reset <= '0'; wait for 20 ns; -- Start the timer start <= '1'; wait for 20 ns; start <= '0'; stop <= '1'; -- Adjust interval up and down adjust_interval_up <= '1'; wait for 10 ns; start <= '1'; stop <= '0'; adjust_interval_up <= '0'; wait for 30 ns; start <= '0'; stop <= '1'; adjust_interval_down <= '1'; wait for 10 ns; start <= '1'; stop <= '0'; adjust_interval_down <= '0'; wait for 20 ns; start <= '0'; stop <= '1'; adjust_interval_up <= '1'; wait for 600 ns; start <= '1'; stop <= '0'; adjust_interval_up <= '0'; -- Wait for the timer to reach the alarm interval (60 clocks) wait for 600 ns; -- Simulate for the required time -- Stop the timer start <= '0'; stop <= '1'; wait for 100 ns; -- Stop the clock and terminate the simulation TbSimEnded <= '1'; wait; end process; end tb;
  
  This should be easier to simulate, I've included a simulation done with Questa.
  
  @T4V0 I just now see your messages, thank you..
  In the meantime, I made something like this...
  What do you think about the specifications that the project requires, should I stick to your code or should I add something from my own code?
  Does your simulation correspond to a time of 1 hour and should there be alarming on the simulation?
  
  Vhdl code:
  
  library ieee;
  use ieee.std_logic_1164.all;
  use ieee.numeric_std.all;
  entity Kitchen_Timer is
  port (
  clk : in std_logic; -- Clock input
  reset : in std_logic; -- Reset input
  start : in std_logic; -- Start button input
  stop : in std_logic; -- Stop button input
  adjust_interval_up : in std_logic; -- Button for increasing alarm interval
  adjust_interval_down : in std_logic; -- Button for decreasing alarm interval
  alarm : out std_logic -- Alarm output
  );
  end entity Kitchen_Timer;
  architecture Behavioral of Kitchen_Timer is
  signal count : integer range 0 to 3600000 := 0; -- Adjust range for 1 hour
  signal alarming : std_logic := '0';
  signal alarm_interval : integer range 600 to 3600000 := 600; -- Adjust range for 1 hour
  begin
  process (clk, reset)
  begin
  if reset = '1' then
  count <= 0;
  alarm_interval <= 600;
  elsif rising_edge(clk) then
  if start = '1' then
  count <= count + 1;
  end if;
  if stop = '1' or count = alarm_interval then
  count <= 0;
  end if;
  if adjust_interval_up = '1' then
  if alarm_interval < 3600000 then
  alarm_interval <= alarm_interval + 600; -- Adjust increment for 1 minute
  end if;
  count <= 0; -- Reset count when adjusting interval
  elsif adjust_interval_down = '1' then
  if alarm_interval > 600 then
  alarm_interval <= alarm_interval - 600; -- Adjust decrement for 1 minute
  end if;
  count <= 0; -- Reset count when adjusting interval
  end if;
  end if;
  end process;
  alarming <= '1' when count >= alarm_interval else '0';
  alarm <= alarming;
  end architecture Behavioral;
  
  Testbench:
  
  library ieee;
  use ieee.std_logic_1164.all;
  entity tb_Kitchen_Timer is
  end tb_Kitchen_Timer;
  architecture tb of tb_Kitchen_Timer is
  component Kitchen_Timer
  port (
  clk : in std_logic;
  reset : in std_logic;
  start : in std_logic;
  stop : in std_logic;
  adjust_interval_up : in std_logic;
  adjust_interval_down : in std_logic;
  alarm : out std_logic
  );
  end component;
  signal clk : std_logic := '0';
  signal reset : std_logic := '0';
  signal start : std_logic := '0';
  signal stop : std_logic := '0';
  signal adjust_interval_up : std_logic := '0';
  signal adjust_interval_down : std_logic := '0';
  signal alarm : std_logic;
  constant TbPeriod : time := 20 ns;
  signal TbClock : std_logic := '0';
  signal TbSimEnded : std_logic := '0';
  begin
  dut : Kitchen_Timer
  port map (
  clk => clk,
  reset => reset,
  start => start,
  stop => stop,
  adjust_interval_up => adjust_interval_up,
  adjust_interval_down => adjust_interval_down,
  alarm => alarm
  );
  -- Clock generation
  TbClock <= not TbClock after TbPeriod/2 when TbSimEnded /= '1' else '0';
  clk <= TbClock;
  stimuli : process
  variable num_ticks : natural;
  begin
  -- Reset generation
  reset <= '1';
  wait for 200 us;
  reset <= '0';
  wait for 200 us;
  -- Start the timer
  start <= '1';
  wait for 500 us;
  -- Adjust interval up and down
  adjust_interval_up <= '1';
  wait for 100 us;
  adjust_interval_up <= '0';
  wait for 100 us;
  adjust_interval_down <= '1';
  wait for 100 us;
  adjust_interval_down <= '0';
  wait for 100 us;
  -- Wait for the timer to reach the alarm interval (3600000 clocks)
  wait for 72 ms; -- Simulate for the required time
  -- Stop the timer
  start <= '0';
  wait for 300 us;
  -- Stop the clock and terminate the simulation
  TbSimEnded <= '1';
  wait;
  end process;
  end tb;
  
  @dejo
  
  What do you think about the specifications that the project requires, should I stick to your code or should I add something from my own code?
  
  I would stick to my code, your alarm isn't going to work properly due to its comparisons as I mentioned in my previous comments. But if you want to improve the code I modified, you can change the adjust_interval_up and adjust_interval_down buttons to be synchronized to their own states rather than the clock (make their own process with their signals added to the signal sensitivity list and add an extra asynchronous condition to zero the counter on the original process). If you don't make a change like this your alarm is going to take up to an hour to adjust its timer range.
  
  Does your simulation correspond to a time of 1 hour and should there be alarming on the simulation?
  
  Yes, if you have a 1/60 Hertz clock signal. And you must have alarming on the simulation as it is crucial to show that it works.
  
  @T4V0
  Is the 1/60 Hz set somewhere or is it set in the code itself?
  When you say that I must have an "alarming" signal on the simulation, is it actually this "alarm" signal that is presented on the simulation or?
  And, do I need to have count signal in simulation?
  
  @dejo
  
  Is the 1/60 Hz set somewhere or is it set in the code itself?
  
  You would set that on the testbench or on your synthesis code, but that is unnecessary, I only said that in case if you tested it on a actual FPGA. If you do that on your testbench, it would take a very long time to simulate.
  
  When you say that I must have an "alarming" signal on the simulation, is it actually this "alarm" signal that is presented on the simulation or?
  
  The alarm signal. The "alarming" is when the alarm signal is in a high logic state.
  
  And, do I need to have count signal in simulation?
  
  I wouldn't say it's mandatory, but it is a good addition to the simulation, keep it.
  
  @T4V0 Thanks a lot for your help, I appreciate it.
  
  @T4V0 How to How can I include the count signal in the simulation so that it is displayed to me
  
  @dejo In your .do script file add this line:
  
  add wave -label "count" -radix unsigned /dut/Kitchen_Timer/count
  
  @T4V0 I use Notepad to write scripts.I don't think it works that way with the code written like this
  
  **library ieee;
  use ieee.std_logic_1164.all;
  use ieee.numeric_std.all;
  entity tb_Kitchen_Timer is
  end tb_Kitchen_Timer;
  architecture tb of tb_Kitchen_Timer is
  signal clk : std_logic := '0';
  signal reset : std_logic := '0';
  signal start : std_logic := '0';
  signal stop : std_logic := '0';
  signal adjust_interval_up : std_logic := '0';
  signal adjust_interval_down : std_logic := '0';
  signal alarm : std_logic;
  constant TbPeriod : time := 10 ns;
  signal TbClock : std_logic := '0';
  signal TbSimEnded : std_logic := '0';
  begin
  dut : entity work.Kitchen_Timer
  port map
  (
  clk => clk,
  reset => reset,
  start => start,
  stop => stop,
  adjust_interval_up => adjust_interval_up,
  adjust_interval_down => adjust_interval_down,
  alarm => alarm
  )
  TbClock <= not TbClock after TbPeriod/2 when TbSimEnded /= '1' else '0'; -- Clock generation
  clk <= TbClock;
  stimuli : process
  variable num_ticks : natural;
  begin
  -- Reset generation
  reset <= '1';
  wait for 20 ns;
  reset <= '0';
  wait for 20 ns;
  -- Start the timer
  start <= '1';
  wait for 20 ns;
  start <= '0';
  stop <= '1';
  -- Adjust interval up and down
  adjust_interval_up <= '1';
  wait for 10 ns;
  start <= '1';
  stop <= '0';
  adjust_interval_up <= '0';
  wait for 30 ns;
  start <= '0';
  stop <= '1';
  adjust_interval_down <= '1';
  wait for 10 ns;
  start <= '1';
  stop <= '0';
  adjust_interval_down <= '0';
  wait for 20 ns;
  start <= '0';
  stop <= '1';
  adjust_interval_up <= '1';
  wait for 600 ns;
  start <= '1';
  stop <= '0';
  adjust_interval_up <= '0';
  -- Wait for the timer to reach the alarm interval (60 clocks)
  wait for 600 ns; -- Simulate for the required time
  -- Stop the timer
  start <= '0';
  stop <= '1';
  wait for 100 ns;
  -- Stop the clock and terminate the simulation
  TbSimEnded <= '1';
  wait;
  end process;
  end tb;
  **
  
  Shouldn't the alarm signal last longer when the alarm interval is increased?
  
  @T4V0
  
  @dejo No, the alarm signal takes a longer time to start rather than the interval when it's set.
  
  You seem to have some trouble picturing the Kitchen Timer itself.
  
  Kitchen timer
  
  Here, when you change the time interval it's the same as when you turn the knob. So it doesn't last longer when you increase the timer, it just takes longer for it to activate.

21 comments