I have made this VHDL code for writing to a USB-chip.
It all runs inside a case statement, where each operation (write, read, ect.) is implemented.
The two write register sections below are equal, only different by the address and data.
Can this be simplified using a procedure or something?
-------- WRITE REGISTER ---------
when s10 =>
-- Txd Cmd
txdata(7 downto 6) <= "10"; -- CMD = register write
txdata(5 downto 0) <= "000100"; -- address
state := s11;
when s11 =>
-- write reg
if nxt = '1' then
txdata <= X"45"; -- output on clock rising edge when nxt is high
stp <= '1';
state := s12;
end if;
when s12 =>
stp <= '0';
txdata <= "00000000"; -- idle
state := s20;
-------- WRITE REGISTER ---------
when s20 =>
-- Txd Cmd
txdata(7 downto 6) <= "10"; -- CMD = register write
txdata(5 downto 0) <= "110101"; -- address
state := s21;
when s21 =>
-- write reg
if nxt = '1' then
txdata <= X"04";
stp <= '1';
state := s22;
end if;
when s22 =>
stp <= '0';
txdata <= "00000000"; -- idle
state := s30;
Yes, use a procedure. Is this not what you asked here already?