PoC.misc.sync.Command

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This module synchronizes a vector of bits from clock-domain Clock1 to clock-domain Clock2. The clock-domain boundary crossing is done by a change comparator, a T-FF, two synchronizer D-FFs and a reconstructive XOR indicating a value change on the input. This changed signal is used to capture the input for the new output. A busy flag is additionally calculated for the input clock-domain. The output has strobe character and is reset to it’s INIT value after one clock cycle.

Constraints:
This module uses sub modules which need to be constrained. Please attend to the notes of the instantiated sub modules.

Entity Declaration:

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entity sync_Command is
  generic (
    BITS          : positive            := 8;                       -- number of bit to be synchronized
    INIT          : std_logic_vector    := x"00000000";             --
    SYNC_DEPTH    : T_MISC_SYNC_DEPTH   := T_MISC_SYNC_DEPTH'low    -- generate SYNC_DEPTH many stages, at least 2
  );
  port (
    Clock1        : in  std_logic;                                  -- <Clock>  input clock
    Clock2        : in  std_logic;                                  -- <Clock>  output clock
    Input         : in  std_logic_vector(BITS - 1 downto 0);        -- @Clock1: input vector
    Output        : out std_logic_vector(BITS - 1 downto 0);        -- @Clock2: output vector
    Busy          : out std_logic;                                  -- @Clock1: busy bit
    Changed       : out std_logic                                   -- @Clock2: changed bit
  );
end entity;