Question

How do I send data represented by a binary string (e.g. "01011101000100111", length is variable) to an std_logic signal given either fixed delay or clock signal? I want this for a testbench so I’d want to be able to arbitrarily change the binary string with as little hassle as possible, so I’m thinking of using generate.

Answer 1

I humbly present a fixed-delay version (it is testbench code after all…). I’ve checked this and it works, but I’m more comfortable in verilog so this code may no be the nicest VHDL ever…

--
-- Clocking out bitstream
--

library ieee;
use ieee.std_logic_1164.all;

entity stackoverflow_strings is
end stackoverflow_strings;

-- this is testbench code, so we can use "wait"s inside a "for" loop.
architecture rtl of stackoverflow_strings is
signal my_output : std_ulogic;
begin

shift_data : process is
constant my_bits : std_logic_vector := B"100101010000100010101";
begin
   my_output <= '0';
   wait for 10 ns; 
   for i in my_bits'range loop
      my_output <= my_bits(i);
      wait for 10 ns;
   end loop; 

   wait;
end process shift_data;

end rtl;