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1 Unique identifier (UID)
The VICCs are uniquely identified by a 64 bits unique identifier (UID). This is used for addressing each VICC uniquely and individually, during the anticollision loop and for one-to-one exchange between a VCD and a VICC.
The UID shall be set permanently by the IC manufacturer in accordance with figure 1.
The UID comprises
• The 8 MSB bits shall be ‘E0‘,
• The IC manufacturer code, on 8 bits according to ISO/IEC 7816-6/AM1,
• A unique serial number on 48 bits assigned by the IC manufacturer.
2 Example
signal c_valid : std_logic; --current validation signal n_valid : std_logic; --next validation signal compare : std_logic_vector(7 downto 0); --compare results begin --! It‘s an D-Reset-Flip-Flop with enable ... pff: process (RST,C) begin if RST = ‘1‘ then c_valid <= ‘0‘; MFCVALID <= ‘0‘; elsif C‘event and C = ‘1‘ then if CE = ‘1‘ then if BCNT = "000" then c_valid <= n_valid; MFCVALID <= compare(6); else c_valid <= c_valid and n_valid; end if; end if; end if; end process; UIDVALID <= c_valid; compare(7) <= ‘1‘ when BYTE = X"E0" else ‘0‘; compare(6) <= ‘1‘ when BYTE = MANUFACT else ‘0‘; compare(5) <= ‘1‘ when BYTE = SERIAL(47 downto 40) else ‘0‘; compare(4) <= ‘1‘ when BYTE = SERIAL(39 downto 32) else ‘0‘; compare(3) <= ‘1‘ when BYTE = SERIAL(31 downto 24) else ‘0‘; compare(2) <= ‘1‘ when BYTE = SERIAL(23 downto 16) else ‘0‘; compare(1) <= ‘1‘ when BYTE = SERIAL(15 downto 8) else ‘0‘; compare(0) <= ‘1‘ when BYTE = SERIAL( 7 downto 0) else ‘0‘; with BCNT select n_valid <= compare(0) when "000", compare(1) when "001", compare(2) when "010", compare(3) when "011", compare(4) when "100", compare(5) when "101", compare(6) when "110", compare(7) when others;
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原文地址：http://www.cnblogs.com/mengdie/p/4433685.html
