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[/] [open8_urisc/] [trunk/] [VHDL/] [o8_gpout.vhd] - Rev 244
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-- Copyright (c)2011, 20219, 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 : o8_gpout -- Description: Provides a single 8-bit GP output register with selectable -- : tri-state control. -- -- Register Map: -- Offset Bitfield Description Read/Write -- 0x00 AAAAAAAA Output Register (RW) -- 0x01 AAAAAAAA Enable/Tri-State Register (RW) -- -- Note that setting a bit to '1' will enable the pin for output, while -- setting it to a '0' will tri-state the pin. -- -- Revision History -- Author Date Change ------------------ -------- --------------------------------------------------- -- Seth Henry 07/28/11 Design Start -- Seth Henry 12/19/19 Renamed to "o8_gpout" to fit "theme" -- Seth Henry 04/10/20 Code Cleanup and comments -- Seth Henry 04/16/20 Modified to make use of Open8 bus record -- Seth Henry 05/18/20 Added write qualification input library ieee; use ieee.std_logic_1164.all; library work; use work.open8_pkg.all; entity o8_gpout is generic( Default_Out : DATA_TYPE := x"00"; Default_En : DATA_TYPE := x"00"; Disable_Tristate : boolean := false; Address : ADDRESS_TYPE ); port( Open8_Bus : in OPEN8_BUS_TYPE; Write_Qual : in std_logic := '1'; Rd_Data : out DATA_TYPE; -- GPO : out DATA_TYPE ); end entity; architecture behave of o8_gpout is alias Clock is Open8_Bus.Clock; alias Reset is Open8_Bus.Reset; constant User_Addr : std_logic_vector(15 downto 1) := Address(15 downto 1); alias Comp_Addr is Open8_Bus.Address(15 downto 1); signal Addr_Match : std_logic := '0'; alias Reg_Sel_d is Open8_Bus.Address(0); signal Reg_Sel_q : std_logic := '0'; signal Wr_En_d : std_logic := '0'; signal Wr_En_q : std_logic := '0'; alias Wr_Data_d is Open8_Bus.Wr_Data; signal Wr_Data_q : DATA_TYPE := x"00"; signal Rd_En_d : std_logic := '0'; signal Rd_En_q : std_logic := '0'; signal User_Out : DATA_TYPE := x"00"; signal User_En : DATA_TYPE := x"00"; begin Addr_Match <= '1' when Comp_Addr = User_Addr else '0'; io_reg: process( Clock, Reset ) begin if( Reset = Reset_Level )then Reg_Sel_q <= '0'; Wr_En_q <= '0'; Wr_Data_q <= x"00"; Rd_En_q <= '0'; Rd_Data <= OPEN8_NULLBUS; User_Out <= Default_Out; if( not Disable_Tristate)then User_En <= Default_En; end if; elsif( rising_edge( Clock ) )then Reg_Sel_q <= Reg_Sel_d; Wr_En_q <= Wr_En_d; Wr_Data_q <= Wr_Data_d; if( Wr_En_q = '1' )then if( Disable_Tristate )then User_Out <= Wr_Data_q; else if( Reg_Sel_q = '0' )then User_Out <= Wr_Data_q; else User_En <= Wr_Data_q; end if; end if; end if; Rd_En_q <= Rd_En_d; Rd_Data <= OPEN8_NULLBUS; if( Rd_En_q = '1' )then Rd_Data <= User_Out; if( (Reg_Sel_q = '1') and (not Disable_Tristate) )then Rd_Data <= User_En; end if; end if; end if; end process; No_Tristates: if( Disable_Tristate )generate GPO <= User_Out; end generate; Tristates: if( not Disable_Tristate )generate Output_Ctl_proc: process( User_Out, User_En ) begin for i in 0 to 7 loop GPO(i) <= 'Z'; if( User_En(i) = '1' )then GPO(i) <= User_Out(i); end if; end loop; end process; end generate; end architecture;