This page of VHDL source code covers 4 bit up down counter vhdl code. An up/down counter is written in VHDL and implemented on a CPLD. The VHDL while loop as well as VHDL generic are also demonstrated. Four different VHDL up/down counters are created in this tutorial: Up/down counter that counts up to a maximum value and then wraps around to 0. An up/down counter is written in VHDL and implemented on a CPLD. The VHDL while loop as well as VHDL generic are also demonstrated. Four different VHDL up/down counters are created in this tutorial: Up/down counter that counts up to a maximum value and then wraps around to 0. 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. This time we'll be designing a 8-bit binary counter using VHDL and then implement it physically on Elbert FPGA Board. PART A: VHDL Code for 8-bit binary counter and simulation. The VHDL Code: library IEEE; use IEEE.STD_LOGIC_1164.ALL; use IEEE.STD_LOGIC_UNSIGNED.ALL; entity counter is Port ( CLK: in STD_LOGIC; OUTPUT: out STD_LOGIC_VECTOR (7 downto 0)); end counter; architecture Behavioral of counter is signal counter: STD_LOGIC_VECTOR(7 downto 0):= (others => '0'); begin OUTPUT CLK, OUTPUT => OUTPUT ); -- Clock process definitions CLK_process:process begin CLK. • The Input clock to Elbert has 12MHz frequency. This is so fast that, if we were to connect the counter outputs to the 8 on-board LEDs, all the 8 LEDs would seem to be on simultaneously! We need a slow clock! • To slow down the input clock, we need a clock divider. We can use the Digital Clock Module (DCM) inside the Spartan-3A family devices, or we can construct our own using a large counter. For now, we will be using the second option. We'll use DCM at a later date. I used a 27-bit counter, and connected the 8 upper bits (MSBs), ie bits 19-26, to the 8 on-board LEDs of Elbert. This gave me the clock frequency of ~11.44Hz at the lowest(least significant bit) LED! New VHDL Code for Elbert. Library IEEE; use IEEE.STD_LOGIC_1164.ALL; use IEEE.STD_LOGIC_UNSIGNED.ALL; entity Switches_LEDs is Port ( LED: out STD_LOGIC_VECTOR(7 downto 0); CLK: in STD_LOGIC ); end Switches_LEDs; architecture Behavioral of Switches_LEDs is signal counter: STD_LOGIC_VECTOR(26 downto 0):= (others => '0'); begin clk_proc: process(CLK) begin if rising_edge(CLK) then counter.
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