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[/] [open8_urisc/] [trunk/] [VHDL/] [vdsm8.vhd] - Rev 264
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-- Copyright (c)2018, 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 : vdsm8 -- Description: 8-bit variable delta-sigma modulator single-bit DAC -- -- Revision History -- Author Date Change ------------------ -------- --------------------------------------------------- -- Seth Henry 04/25/18 Initial design -- Seth Henry 04/14/20 Code cleanup and revision section added library ieee; use ieee.std_logic_1164.all; use ieee.std_logic_unsigned.all; use ieee.std_logic_arith.all; entity vdsm8 is generic( Reset_Level : std_logic := '1'; -- Do not adjust alone! DELTA constants must be -- changed as well. DAC_Width : integer := 8 ); port( Clock : in std_logic; Reset : in std_logic; DACin : in std_logic_vector(DAC_Width-1 downto 0); DACout : out std_logic ); end entity; architecture behave of vdsm8 is 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; constant DELTA_1_I : integer := 1; constant DELTA_2_I : integer := 5; constant DELTA_3_I : integer := 25; constant DELTA_4_I : integer := 75; constant DELTA_5_I : integer := 125; constant DELTA_6_I : integer := 195; constant DELTA_1 : std_logic_vector(DAC_Width-1 downto 0) := conv_std_logic_vector(DELTA_1_I, DAC_Width); constant DELTA_2 : std_logic_vector(DAC_Width-1 downto 0) := conv_std_logic_vector(DELTA_2_I, DAC_Width); constant DELTA_3 : std_logic_vector(DAC_Width-1 downto 0) := conv_std_logic_vector(DELTA_3_I, DAC_Width); constant DELTA_4 : std_logic_vector(DAC_Width-1 downto 0) := conv_std_logic_vector(DELTA_4_I, DAC_Width); constant DELTA_5 : std_logic_vector(DAC_Width-1 downto 0) := conv_std_logic_vector(DELTA_5_I, DAC_Width); constant DELTA_6 : std_logic_vector(DAC_Width-1 downto 0) := conv_std_logic_vector(DELTA_6_I, DAC_Width); constant MAX_PERIOD : integer := 2**DAC_Width; constant DIV_WIDTH : integer := DAC_Width * 2; constant PADJ_1_I : integer := DELTA_1_I * MAX_PERIOD; constant PADJ_2_I : integer := DELTA_2_I * MAX_PERIOD; constant PADJ_3_I : integer := DELTA_3_I * MAX_PERIOD; constant PADJ_4_I : integer := DELTA_4_I * MAX_PERIOD; constant PADJ_5_I : integer := DELTA_5_I * MAX_PERIOD; constant PADJ_6_I : integer := DELTA_6_I * MAX_PERIOD; constant PADJ_1 : std_logic_vector(DIV_WIDTH-1 downto 0) := conv_std_logic_vector(PADJ_1_I,DIV_WIDTH); constant PADJ_2 : std_logic_vector(DIV_WIDTH-1 downto 0) := conv_std_logic_vector(PADJ_2_I,DIV_WIDTH); constant PADJ_3 : std_logic_vector(DIV_WIDTH-1 downto 0) := conv_std_logic_vector(PADJ_3_I,DIV_WIDTH); constant PADJ_4 : std_logic_vector(DIV_WIDTH-1 downto 0) := conv_std_logic_vector(PADJ_4_I,DIV_WIDTH); constant PADJ_5 : std_logic_vector(DIV_WIDTH-1 downto 0) := conv_std_logic_vector(PADJ_5_I,DIV_WIDTH); constant PADJ_6 : std_logic_vector(DIV_WIDTH-1 downto 0) := conv_std_logic_vector(PADJ_6_I,DIV_WIDTH); signal DACin_q : std_logic_vector(DAC_Width-1 downto 0); signal Divisor : std_logic_vector(DIV_WIDTH-1 downto 0); signal Dividend : std_logic_vector(DIV_WIDTH-1 downto 0); signal q : std_logic_vector(DIV_WIDTH*2-1 downto 0); signal diff : std_logic_vector(DIV_WIDTH downto 0); constant CB : integer := ceil_log2(DIV_WIDTH); signal count : std_logic_vector(CB-1 downto 0); signal Next_Width : std_logic_vector(DAC_Width-1 downto 0); signal Next_Period : std_logic_vector(DAC_Width-1 downto 0); signal PWM_Width : std_logic_vector(DAC_Width-1 downto 0); signal PWM_Period : std_logic_vector(DAC_Width-1 downto 0); signal Width_Ctr : std_logic_vector(DAC_Width-1 downto 0); signal Period_Ctr : std_logic_vector(DAC_Width-1 downto 0); begin diff <= ('0' & q(DIV_WIDTH*2-2 downto DIV_WIDTH-1)) - ('0' & Divisor); Dividend <= PADJ_2 when DACin_q >= DELTA_2_I and DACin_q < DELTA_3_I else PADJ_3 when DACin_q >= DELTA_3_I and DACin_q < DELTA_4_I else PADJ_4 when DACin_q >= DELTA_4_I and DACin_q < DELTA_5_I else PADJ_5 when DACin_q >= DELTA_5_I and DACin_q < DELTA_6_I else PADJ_6 when DACin_q >= DELTA_6_I else PADJ_1; Next_Width <= DELTA_1 when DACin_q >= DELTA_1_I and DACin_q < DELTA_2_I else DELTA_2 when DACin_q >= DELTA_2_I and DACin_q < DELTA_3_I else DELTA_3 when DACin_q >= DELTA_3_I and DACin_q < DELTA_4_I else DELTA_4 when DACin_q >= DELTA_4_I and DACin_q < DELTA_5_I else DELTA_5 when DACin_q >= DELTA_5_I and DACin_q < DELTA_6_I else DELTA_6 when DACin_q >= DELTA_6_I else (others => '0'); Next_Period <= q(7 downto 0) - 1; vDSM_proc: process( Clock, Reset ) begin if( Reset = Reset_Level )then q <= (others => '0'); count <= (others => '1'); Divisor <= (others => '0'); DACin_q <= (others => '0'); PWM_Width <= (others => '0'); PWM_Period <= (others => '0'); Period_Ctr <= (others => '0'); Width_Ctr <= (others => '0'); DACout <= '0'; elsif( rising_edge(Clock) )then q <= diff(DIV_WIDTH-1 downto 0) & q(DIV_WIDTH-2 downto 0) & '1'; if( diff(DIV_WIDTH) = '1' )then q <= q(DIV_WIDTH*2-2 downto 0) & '0'; end if; count <= count + 1; if( count = DIV_WIDTH )then PWM_Width <= Next_Width; PWM_Period <= Next_Period; DACin_q <= DACin; Divisor <= (others => '0'); Divisor(DAC_Width-1 downto 0) <= DACin_q; q <= conv_std_logic_vector(0,DIV_WIDTH) & Dividend; count <= (others => '0'); end if; Period_Ctr <= Period_Ctr - 1; Width_Ctr <= Width_Ctr - 1; DACout <= '1'; if( Width_Ctr = 0 )then DACout <= '0'; Width_Ctr <= (others => '0'); end if; if( Period_Ctr = 0 )then Period_Ctr <= PWM_Period; Width_Ctr <= PWM_Width; end if; end if; end process; end architecture;
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