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71 lines
2.4 KiB
VHDL
71 lines
2.4 KiB
VHDL
--============================================================================
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--
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-- VHDL implementation of the 74LS244 octal line driver with tristate outputs
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-- Copyright (C) 2018, 2019 Ace
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--
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-- Permission is hereby granted, free of charge, to any person obtaining a
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-- copy of this software and associated documentation files (the "Software"),
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-- to deal in the Software without restriction, including without limitation
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-- the rights to use, copy, modify, merge, publish, distribute, sublicense,
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-- and/or sell copies of the Software, and to permit persons to whom the
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-- Software is furnished to do so, subject to the following conditions:
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--
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-- The above copyright notice and this permission notice shall be included in
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-- all copies or substantial portions of the Software.
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--
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-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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-- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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-- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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-- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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-- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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-- FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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-- DEALINGS IN THE SOFTWARE.
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--
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--============================================================================
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--Chip pinout:
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/* _____________
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n_g1 |_|1 20|_| VCC
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_| |_
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a1(0) |_|2 19|_| n_g2
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_| |_
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y2(3) |_|3 18|_| y1(0)
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_| |_
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a1(1) |_|4 17|_| a2(3)
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_| |_
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y2(2) |_|5 16|_| y1(1)
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a1(2) |_|6 15|_| a2(2)
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y2(1) |_|7 14|_| y1(2)
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a1(3) |_|8 13|_| a2(1)
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y2(0) |_|9 12|_| y1(3)
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GND |_|10 11|_| a2(0)
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|_____________|
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*/
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library ieee;
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use ieee.std_logic_1164.all;
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entity ls244 is
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port
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(
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n_g1, n_g2 : in std_logic;
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a1 : in std_logic_vector(3 downto 0);
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a2 : in std_logic_vector(3 downto 0);
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y1 : out std_logic_vector(3 downto 0);
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y2 : out std_logic_vector(3 downto 0)
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);
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end ls244;
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architecture arch of ls244 is
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begin
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y1 <= a1 when not n_g1
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else (others => 'Z');
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y2 <= a2 when not n_g2
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else (others => 'Z');
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end arch; |