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[/] [open8_urisc/] [trunk/] [VHDL/] [status_led.vhd] - Rev 251
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-- Copyright (c)2020 Jeremy Seth Henry -- All rights reserved. -- -- Redistribution and use in source and binary forms, with or without -- modification, are permitted provided that the following conditions are met: -- * Redistributions of source code must retain the above copyright -- notice, this list of conditions and the following disclaimer. -- * Redistributions in binary form must reproduce the above copyright -- notice, this list of conditions and the following disclaimer in the -- documentation and/or other materials provided with the distribution, -- where applicable (as part of a user interface, debugging port, etc.) -- -- THIS SOFTWARE IS PROVIDED BY JEREMY SETH HENRY ``AS IS'' AND ANY -- EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED -- WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE -- DISCLAIMED. IN NO EVENT SHALL JEREMY SETH HENRY BE LIABLE FOR ANY -- DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES -- (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; -- LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND -- ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT -- (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF -- THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. -- -- VHDL Units : status_led -- Description: Provides a multi-state status LED controller -- -- LED Modes: -- 0x0 - LED is fully off -- 0x1 - LED is fully on -- 0x2 - LED is dimmed to 50% -- 0x3 - LED Toggles at 1Hz -- 0x4 - LED fades in and out -- -- Revision History -- Author Date Change ------------------ -------- --------------------------------------------------- -- Seth Henry 05/24/20 Created as a separate sub-component library ieee; use ieee.std_logic_1164.all; use ieee.std_logic_unsigned.all; use ieee.std_logic_arith.all; use ieee.std_logic_misc.all; entity status_led is generic( Sys_Freq : real; Reset_Level : std_logic ); port( Clock : in std_logic; Reset : in std_logic; LED_Mode : in std_logic_vector(2 downto 0); LED_Out : out std_logic ); end entity; architecture behave of status_led is -- hold the supplied integer. function ceil_log2 (x : in natural) return natural is variable retval : natural; begin retval := 1; while ((2**retval) - 1) < x loop retval := retval + 1; end loop; return retval; end function; signal Dim50Pct_Out : std_logic := '0'; constant TAP1 : integer := 16; constant TAP2 : integer := 21; constant TAP3 : integer := 22; constant TAP4 : integer := 23; constant Init_Seed : std_logic_vector(23 downto 0) := x"000001"; signal d0 : std_logic := '0'; signal LFSR_poly : std_logic_vector(23 downto 0) := (others => '0'); signal Cycle_Toggle : std_logic; constant TIMER_MSB : integer range 9 to 20 := 18; signal Fade_Timer1 : std_logic_vector(TIMER_MSB downto 0) := (others => '0'); signal Fade_Timer2 : std_logic_vector(TIMER_MSB downto 0) := (others => '0'); signal Fade_Out : std_logic := '0'; begin Output_FF: process( Clock, Reset ) begin if( Reset = Reset_Level )then LED_Out <= '0'; elsif( rising_edge(Clock) )then LED_Out <= '0'; case( LED_Mode )is when "001" => LED_Out <= '1'; when "010" => LED_Out <= Dim50Pct_Out; when "011" => LED_Out <= Cycle_Toggle; when "100" => LED_Out <= Fade_out; when others => null; end case; end if; end process; d0 <= LFSR_poly(TAP4) xnor LFSR_poly(TAP3) xnor LFSR_poly(TAP2) xnor LFSR_poly(TAP1); Timer_proc: process( Clock, Reset ) begin if( Reset = Reset_Level )then Dim50Pct_Out <= '0'; LFSR_poly <= Init_Seed; Cycle_Toggle <= '0'; Fade_Timer1 <= (others => '0'); Fade_Timer2 <= (others => '0'); Fade_out <= '0'; elsif( rising_edge(Clock) )then Dim50Pct_Out <= not Dim50Pct_Out; LFSR_poly <= LFSR_poly(22 downto 0) & d0; if( LFSR_poly = Init_Seed )then Cycle_Toggle <= not Cycle_Toggle; end if; Fade_Timer1 <= Fade_Timer1 - 1; Fade_Timer2 <= Fade_Timer2 - 1; if( or_reduce(Fade_Timer2) = '0' )then Fade_Timer2(TIMER_MSB downto TIMER_MSB - 8) <= (others => '1'); Fade_Timer2(TIMER_MSB - 9 downto 0 ) <= (others => '0'); end if; Fade_out <= Fade_Timer1(TIMER_MSB) xor Fade_Timer2(TIMER_MSB); end if; end process; end architecture;
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