VHDL - obousmerna sbernice

[Petr Sremr]

Zdravim,

> Doporucujem vo vnutri pracovat s 2 nezavilymi zbernicami,
> vstupna - rozvedie vstupne data do reg. /zapisovat WR najlepsie synchronne 
> ak sa da/
> vystupna - vpodstate mux. na zaklade adresy
> 
> Obe zbernice spojit na pine pomocou vlozenych komponentov
> IBUF - pre vstupnu
> OBUFT /OBUFE/ - pre vystupnu trojstavovu, na tomto mieste priamo riadit 3 
> stav /signalom RD&CS/

Tak jsem to nejak takto zkusil. Ty komponenty jsou super.

Tady je muj pokus pro jednobitovy pripad. Prosim, muzete se podivat, kde 
delam chyby. S VHDL zacinam, a zrejme mi porad unikaji zakladni 
principy. Mimo jine, dostavam tyto upozrneni:

WARNING:Xst:766 - D:/Projects/Logic_01/jspp/jspp1/jspp1.vhd (Line 56). 
Generating a Black Box for component <obufe>.
WARNING:Xst:766 - D:/Projects/Logic_01/jspp/jspp1/jspp1.vhd (Line 60). 
Generating a Black Box for component <ibuf>.
WARNING:Xst:819 - D:/Projects/Logic_01/jspp/jspp1/jspp1.vhd (Line 64). 
The following signals are missing in the process sens
itivity list: rw.

------------------------------------------------------------------------
--
--    Zapis:                  Cteni:
--       |                        |
--       |-\________/--           |-------------
--    RW |=============>       RW |=============>
--       |                        |
--       |----\___/----           |----\___/----
--    E  |=============>       E  |=============>
--       |                        |
--       |xxxWWWxxxxxxx           |xxxxxWWWxxxxx
--    Dx |=============>       Dx |=============>
--
--     po celou dobu je
--     na sbernici 3.stav
--
--     x ... lib. data           x ... 3.stav
--     W ... platna data         W ... platna data
--           (strobovana sest.        (sbernice aktivni)
--            hranou)
--
------------------------------------------------------------------------

-- http://toolbox.xilinx.com/docsan/xilinx5/data/docs/lib/lib0318_302.html

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity jednoduchy_obvod is
     Port (D: inout STD_LOGIC;
           RW: in STD_LOGIC;
           E: in STD_LOGIC);
end jednoduchy_obvod;

architecture moje_architektura of jednoduchy_obvod is

component OBUFE
     port (O : out STD_LOGIC;
           E : in STD_LOGIC;
           I : in STD_LOGIC);
end component;

component IBUF
     port (O : out STD_LOGIC;
           I : in STD_LOGIC);
end component;

     signal r: STD_LOGIC; -- registr, ktery. ctu/zapisuju
     signal en: STD_LOGIC;
     signal i: STD_LOGIC;

begin

     output : OBUFE
         port map (O => D,
                   E => en,
                   I => r);
     input : IBUF
         port map (O => i,
                   I => D);

     pr_1: process (E)
     begin
         if (E'event and E = '0') then
             if (RW = '0') then
                 r <= i;
             end if;
         end if;
         en <= RW and not E;
     end process;

end moje_architektura;

--
Petr Sremr
HW group