Xilinx RocketIO - Page 99

RocketIO™ Transceiver User Guide www.xilinx.com 99
UG024 (v3.0) February 22, 2007
Other Important Design Notes
R
-- usrclk2 -- RXUSRCLK2
-- rxreset -- RXRESET
-- rxdata[31:0] RXDATA[31:0] -- (commas aligned to
-- [31:24] or [15:8])
-- rxisk[3:0] - RXCHARISK[3:0]
-- rxrealign -- RXREALIGN
-- rxcommadet -- RXCOMMADET
-- rxchariscomma3 -- RXCHARISCOMMA[3]
-- rxchariscomma1 -- RXCHARISCOMMA[1]
--
LIBRARY IEEE;
USE IEEE.std_logic_1164.all;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.Numeric_STD.all;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
ENTITY align_comma_32 IS
PORT (
aligned_data : OUT std_logic_vector(31 DOWNTO 0);
aligned_rxisk : OUT std_logic_vector(3 DOWNTO 0);
sync : OUT std_logic;
usrclk2 : IN std_logic;
rxreset : IN std_logic;
rxdata : IN std_logic_vector(31 DOWNTO 0);
rxisk : IN std_logic_vector(3 DOWNTO 0);
rxrealign : IN std_logic;
rxcommadet : IN std_logic;
rxchariscomma3 : IN std_logic;
rxchariscomma1 : IN std_logic);
END ENTITY align_comma_32;
ARCHITECTURE translated OF align_comma_32 IS
SIGNAL rxdata_reg : std_logic_vector(15 DOWNTO 0);
SIGNAL rxisk_reg : std_logic_vector(1 DOWNTO 0);
SIGNAL byte_sync : std_logic;
SIGNAL wait_to_sync : std_logic_vector(3 DOWNTO 0);
SIGNAL count : std_logic;
SIGNAL rxdata_hold : std_logic_vector(31 DOWNTO 0);
SIGNAL rxisk_hold : std_logic_vector(3 DOWNTO 0);
SIGNAL sync_hold : std_logic;
BEGIN
aligned_data <= rxdata_hold;
aligned_rxisk <= rxisk_hold;
sync <= sync_hold;
-- This process maintains wait_to_sync and count,
-- which are used only to
-- maintain output sync; this provides some idea
-- of when the output is properly
-- aligned, with the comma in aligned_data[31:24].
-- The counter is set to a high value
-- whenever the elastic buffer is reinitialized;
-- that is, upon asserted RXRESET or
-- RXREALIGN. Count-down is enabled whenever a
-- comma is known to have
-- come through the comma detection circuit, that
Product Not Recommended for New Designs