After finishing the design of MC1. Should implement an 8- bit BCD up/down Counter. 4 bit up counter. VHDL Increment 10-bit Program. Vhdl Program For 8 Bit Up Down Counter. 7/11/2017 0 Comments Mod-n Synchronous Counter, Cascading Counters, Up-Down Counter Digital Logic Design Engineering Electronics Engineering Computer Science. Synchronous Counter. In the previous Asynchronous binary counter tutorial, we saw that the output of one counter stage is connected directly to the clock input of the. Clock Divider is also known. Nice with some HDL on Code Review. I'll contribute with my opinions. All-in-all, I find the code all well-written. Opinions not already covered in previous answers • A more standard way of setting count at reset would be (others => '0'). • That is, as opposed to hard-coding a bit/hex literal - even if you for some reason hard-code the width as you have done, (others => '0') is more standard in this case. • You might have a good reason for asynchronous reset, but if not, synchronous reset is a better habit. ![]() • You often see these asynchronous resets, it is unfortunately a more common habit, since that's what is (or was) most often taught. • See my motivations here: Opinions already covered/partly covered Somewhat in order of importance (in my subjective opinion). • Define the roll-over behaviour. • The behaviour is actually defined for an unsigned in numeric_std: any carry bits will be ignored so the unsigned will roll-over. However, neither simulators nor synthesis tools should be trusted on following this. (And even less, humans reading the code.) Also; it is good to really think about what behaviour you desire, or is the most stable: roll-over or saturate? I'll take the chance to give two comments on this choice: • For synthesis, roll-over rather than saturation will yield less logic and improved timing. The tool will be able to use a counter macro right-off. • If reaching max count is expected never to happen, add an assertion so a simulation will flag in that case. Then still code the RTL behaviour explicitly to roll-over (less logic, better timing) if there aren't stability reasons to code it to saturate. • Parameterize the width. Put it in a constant or generic. • Generate the clock separately (e.g. Contrary to what Aseem Bansal states, there is no need to use std_logic alone. Your use of std_ulogic is fine. One place where there is a trade-off to be pondered is on your top-level entity (the one which defines the whole chip). The tools that generate the output will create you a simulation model with all the gates and delays in, but it will have std_logic on the IO pins. This can be plugged straight into your existing testbench if you've already used std_logic at the top. You can avoid lots of duplicated typing by using direct instantiation. You don't need this at all: component counter32 port ( clk: in std_ulogic; ena: in std_ulogic; rst: in std_ulogic; q: out std_ulogic_vector(31 downto 0)); end component; if you do this: dut: entity work.counter32 port map ( clk => clk, ena => ena, rst => rst, q => q); This is the preferred method these days. In your testbench, I would separate out the clock generation to its own process. Or even to a single line: clk. I am a complete beginner in VHDL, so I was hoping that someone could help me with this project I am working on. I need to realize rectangular pulse generator which frequency can be changed in the range 0 through 255. Frequency value in kHz must be shown binary on 8 LED diodes on the development board. For adjusting the output pulse frequency two buttons are used(incrementing/decrementing). When the button is held down for more than a second, the frequency is automatically incrementing/decrementing. I wrote some code, but in Xilinx I get a ton of warnings. Can somebody explain them to me? The second process of your state machine is the culprit. A process should be either synchronous or combinational, not a mix of both. A synchronous process has this form: process(reset, clk) begin if (reset = '0' then signals. Library IEEE; use IEEE.STD_LOGIC_1164. ALL; use IEEE.STD_LOGIC_ARITH. ALL; use IEEE.STD_LOGIC_UNSIGNED. ALL; entity Counter2_VHDL is port ( Clock_enable_B: in std_logic; Clock: in std_logic; Reset: in std_logic; Output: out std_logic_vector ( 0 to 3 )); end Counter2_VHDL; architecture Behavioral of Counter2_VHDL is signal temp: std_logic_vector ( 0 to 3 ); begin process ( Clock, Reset ) begin if Reset = '1' then temp. I am trying to make a four bit up/down modulo10 counter. Button1 - counts up, Button2 - counts down. I'm trying to do it using rising_edge command but for two signals I can’t define with button was pressed. So in next version of program I want detect button using if statement. Library IEEE; use IEEE.std_logic_1164.all, IEEE.numeric_std.all; ENTITY counter is generic (n:natural:=4); port( button1: in std_logic; button2: in std_logic; clear: in std_logic; C: out std_logic; OUT1: out std_logic_vector(n-1 downto 0) ); END counter; ARCHITECTURE beh of counter is begin p0:process (button1, clear) is variable count: unsigned (n-1 downto 0); begin if clear = '1' then count:= (others=>'0'); elsif button1='1' then count:=count+1; elsif count=10 then count:=(others=>'0'); C'1'); C. You should use a CLOCK signal to use rising_edge, I created a clock signal in your entity: clock: in std_ulogic; After this you should put in your process sensitivy the CLOCK signal and the button2 signal, like this: p0:process (button1, button2, clear, clock) is My simulation with this conditions work correctly, when I press button1 the count goes up, when I press button2 count goes down.
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