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Last change
on this file since 14876 was 156, checked in by qweitzel, 16 years ago |
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First check-in of VHDL code for FTU: counters, dcm, spi
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File size:
952 bytes
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| 1 | -- File: upcnt16.vhd
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| 2 | --
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| 3 | -- Purpose: Up 16-bit counter
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| 4 | --
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| 5 | -- Created: 7-25-00 ALS
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| 6 | --
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| 7 |
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| 8 | library IEEE;
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| 9 | use IEEE.std_logic_1164.all;
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| 10 | use IEEE.std_logic_arith.all;
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| 11 |
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| 12 | entity upcnt16 is
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| 13 | port(
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| 14 | full : out STD_LOGIC;
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| 15 | clr : in STD_LOGIC;
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| 16 | reset : in STD_Logic;
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| 17 | clk : in STD_LOGIC
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| 18 | );
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| 19 |
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| 20 | end upcnt16;
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| 21 |
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| 22 | architecture DEFINITION of upcnt16 is
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| 23 |
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| 24 | constant RESET_ACTIVE : std_logic := '0';
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| 25 | constant Cnt_full : Unsigned (15 DOWNTO 0) :="1111111111111111";
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| 26 |
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| 27 | signal q : Unsigned (15 DOWNTO 0);
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| 28 |
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| 29 | begin
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| 30 |
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| 31 | process(clk, reset, clr)
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| 32 | begin
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| 33 |
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| 34 | if ((reset OR clr)='1') then
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| 35 | q <= (others => '0');-- Clear output register
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| 36 | elsif (clk'event) and clk = '1' and (not(q = Cnt_full)) then-- On rising edge of clock count
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| 37 | q <= q + 1;
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| 38 | end if;
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| 39 |
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| 40 | end process;
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| 41 |
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| 42 | process(q)
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| 43 | begin
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| 44 |
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| 45 | if (q = Cnt_full) then
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| 46 | full <= '1';
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| 47 | else
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| 48 | full <= '0';
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| 49 | end if;
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| 50 |
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| 51 | end process;
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| 52 |
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| 53 | end DEFINITION;
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