--===========================================================================--
|
--===========================================================================--
|
-- --
|
-- --
|
-- pia_timer.vhd - Synthesizable Parallel Interface Adapter with Timer --
|
-- pia_timer.vhd - Synthesizable Parallel Interface Adapter with Timer --
|
-- --
|
-- --
|
--===========================================================================--
|
--===========================================================================--
|
--
|
--
|
-- File name : pia_timer.vhd
|
-- File name : pia_timer.vhd
|
--
|
--
|
-- Entity name : pia_timer
|
-- Entity name : pia_timer
|
--
|
--
|
-- Purpose : Implements 2 x 8 bit parallel I/O ports
|
-- Purpose : Implements 2 x 8 bit parallel I/O ports
|
-- with 8 bit presetable counter.
|
-- with 8 bit presetable counter.
|
-- Port A Data = output connected to presettable counter input
|
-- Port A Data = output connected to presettable counter input
|
-- Port B Data = input connected to counter output
|
-- Port B Data = input connected to counter output
|
-- Used with Digilent Spartan 3E starter board
|
-- Used with Digilent Spartan 3E starter board
|
-- to implement a single step trace function.
|
-- to implement a single step trace function.
|
--
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--
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-- Dependencies : ieee.std_logic_1164
|
-- Dependencies : ieee.std_logic_1164
|
-- ieee.std_logic_unsigned
|
-- ieee.std_logic_unsigned
|
-- unisim.vcomponents
|
-- unisim.vcomponents
|
--
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--
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-- Author : John E. Kent
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-- Author : John E. Kent
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--
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--
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-- Email : dilbert57@opencores.org
|
-- Email : dilbert57@opencores.org
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--
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--
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-- Web : http://opencores.org/project,system09
|
-- Web : http://opencores.org/project,system09
|
--
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--
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-- Description : Register Memory Map
|
-- Description : Register Memory Map
|
--
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--
|
-- Base + $00 - Port A Data & Direction register
|
-- Base + $00 - Port A Data & Direction register
|
-- Base + $01 - Port A Control register
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-- Base + $01 - Port A Control register
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-- Base + $02 - Port B Data & Direction Direction Register
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-- Base + $02 - Port B Data & Direction Direction Register
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-- Base + $03 - Port B Control Register
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-- Base + $03 - Port B Control Register
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--
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--
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-- Copyright (C) 2004 - 2010 John Kent
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-- Copyright (C) 2004 - 2010 John Kent
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--
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--
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-- This program is free software: you can redistribute it and/or modify
|
-- This program is free software: you can redistribute it and/or modify
|
-- it under the terms of the GNU General Public License as published by
|
-- it under the terms of the GNU General Public License as published by
|
-- the Free Software Foundation, either version 3 of the License, or
|
-- the Free Software Foundation, either version 3 of the License, or
|
-- (at your option) any later version.
|
-- (at your option) any later version.
|
--
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--
|
-- This program is distributed in the hope that it will be useful,
|
-- This program is distributed in the hope that it will be useful,
|
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
|
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
|
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
-- GNU General Public License for more details.
|
-- GNU General Public License for more details.
|
--
|
--
|
-- You should have received a copy of the GNU General Public License
|
-- You should have received a copy of the GNU General Public License
|
-- along with this program. If not, see <http://www.gnu.org/licenses/>.
|
-- along with this program. If not, see <http://www.gnu.org/licenses/>.
|
--
|
--
|
--===========================================================================--
|
--===========================================================================--
|
-- --
|
-- --
|
-- Revision History --
|
-- Revision History --
|
-- --
|
-- --
|
--===========================================================================--
|
--===========================================================================--
|
--
|
--
|
-- Version Author Date Description
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-- Version Author Date Description
|
-- 0.0 John Kent 1st May 2004 Initial version developed from ioport.vhd
|
-- 0.0 John Kent 1st May 2004 Initial version developed from ioport.vhd
|
--
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--
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-- 1.0 John Kent 22nd April 2006 Removed I/O ports and hard wired a binary
|
-- 1.0 John Kent 22nd April 2006 Removed I/O ports and hard wired a binary
|
-- down counter. Port A is the preset output.
|
-- down counter. Port A is the preset output.
|
-- Port B is the timer count input.
|
-- Port B is the timer count input.
|
-- CA1 & CB1 are interrupt inputs
|
-- CA1 & CB1 are interrupt inputs
|
-- CA2 is the counter load (active low)
|
-- CA2 is the counter load (active low)
|
-- CB2 is the counter reset (active high)
|
-- CB2 is the counter reset (active high)
|
-- It may be necessary to offset the counter
|
-- It may be necessary to offset the counter
|
-- to compensate for differences in cpu cycle
|
-- to compensate for differences in cpu cycle
|
-- times between FPGA and real 6809 systems.
|
-- times between FPGA and real 6809 systems.
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--
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--
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-- 1.1 John Kent 24th May 2006 Modified counter to subtract one from preset
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-- 1.1 John Kent 24th May 2006 Modified counter to subtract one from preset
|
-- so FPGA version of the CMC_BUG monitor is
|
-- so FPGA version of the CMC_BUG monitor is
|
-- compatible with the reference design.
|
-- compatible with the reference design.
|
--
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--
|
-- 1.2 John Kent 30th May 2010 Revised header and added updated GPL
|
-- 1.2 John Kent 30th May 2010 Revised header and added updated GPL
|
--
|
--
|
--===========================================================================----
|
--===========================================================================----
|
--
|
--
|
-- Memory Map
|
-- Memory Map
|
--
|
--
|
-- IO + $00 - Port A Data & Direction register
|
-- IO + $00 - Port A Data & Direction register
|
-- IO + $01 - Port A Control register
|
-- IO + $01 - Port A Control register
|
-- IO + $02 - Port B Data & Direction Direction Register
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-- IO + $02 - Port B Data & Direction Direction Register
|
-- IO + $03 - Port B Control Register
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-- IO + $03 - Port B Control Register
|
--
|
--
|
|
|
library ieee;
|
library ieee;
|
use ieee.std_logic_1164.all;
|
use ieee.std_logic_1164.all;
|
use ieee.std_logic_unsigned.all;
|
use ieee.std_logic_unsigned.all;
|
library unisim;
|
library unisim;
|
use unisim.vcomponents.all;
|
use unisim.vcomponents.all;
|
|
|
entity pia_timer is
|
entity pia_timer is
|
port (
|
port (
|
clk : in std_logic;
|
clk : in std_logic;
|
rst : in std_logic;
|
rst : in std_logic;
|
cs : in std_logic;
|
cs : in std_logic;
|
rw : in std_logic;
|
rw : in std_logic;
|
addr : in std_logic_vector(1 downto 0);
|
addr : in std_logic_vector(1 downto 0);
|
data_in : in std_logic_vector(7 downto 0);
|
data_in : in std_logic_vector(7 downto 0);
|
data_out : out std_logic_vector(7 downto 0);
|
data_out : out std_logic_vector(7 downto 0);
|
irqa : out std_logic;
|
irqa : out std_logic;
|
irqb : out std_logic
|
irqb : out std_logic
|
);
|
);
|
end;
|
end;
|
|
|
architecture pia_arch of pia_timer is
|
architecture pia_arch of pia_timer is
|
|
|
signal pa : std_logic_vector(7 downto 0);
|
signal pa : std_logic_vector(7 downto 0);
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signal porta_ddr : std_logic_vector(7 downto 0);
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signal porta_ddr : std_logic_vector(7 downto 0);
|
signal porta_data : std_logic_vector(7 downto 0);
|
signal porta_data : std_logic_vector(7 downto 0);
|
signal porta_ctrl : std_logic_vector(5 downto 0);
|
signal porta_ctrl : std_logic_vector(5 downto 0);
|
signal porta_read : std_logic;
|
signal porta_read : std_logic;
|
|
|
signal pb : std_logic_vector(7 downto 0);
|
signal pb : std_logic_vector(7 downto 0);
|
signal portb_ddr : std_logic_vector(7 downto 0);
|
signal portb_ddr : std_logic_vector(7 downto 0);
|
signal portb_data : std_logic_vector(7 downto 0);
|
signal portb_data : std_logic_vector(7 downto 0);
|
signal portb_ctrl : std_logic_vector(5 downto 0);
|
signal portb_ctrl : std_logic_vector(5 downto 0);
|
signal portb_read : std_logic;
|
signal portb_read : std_logic;
|
signal portb_write : std_logic;
|
signal portb_write : std_logic;
|
|
|
signal ca1 : std_logic;
|
signal ca1 : std_logic;
|
signal ca1_del : std_logic;
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signal ca1_del : std_logic;
|
signal ca1_rise : std_logic;
|
signal ca1_rise : std_logic;
|
signal ca1_fall : std_logic;
|
signal ca1_fall : std_logic;
|
signal ca1_edge : std_logic;
|
signal ca1_edge : std_logic;
|
signal irqa1 : std_logic;
|
signal irqa1 : std_logic := '0';
|
|
|
signal ca2 : std_logic;
|
signal ca2 : std_logic;
|
signal ca2_del : std_logic;
|
signal ca2_del : std_logic;
|
signal ca2_rise : std_logic;
|
signal ca2_rise : std_logic;
|
signal ca2_fall : std_logic;
|
signal ca2_fall : std_logic;
|
signal ca2_edge : std_logic;
|
signal ca2_edge : std_logic;
|
signal irqa2 : std_logic;
|
signal irqa2 : std_logic := '0';
|
signal ca2_out : std_logic;
|
signal ca2_out : std_logic;
|
|
|
signal cb1 : std_logic;
|
signal cb1 : std_logic;
|
signal cb1_del : std_logic;
|
signal cb1_del : std_logic;
|
signal cb1_rise : std_logic;
|
signal cb1_rise : std_logic;
|
signal cb1_fall : std_logic;
|
signal cb1_fall : std_logic;
|
signal cb1_edge : std_logic;
|
signal cb1_edge : std_logic;
|
signal irqb1 : std_logic;
|
signal irqb1 : std_logic := '0';
|
|
|
signal cb2 : std_logic;
|
signal cb2 : std_logic;
|
signal cb2_del : std_logic;
|
signal cb2_del : std_logic;
|
signal cb2_rise : std_logic;
|
signal cb2_rise : std_logic;
|
signal cb2_fall : std_logic;
|
signal cb2_fall : std_logic;
|
signal cb2_edge : std_logic;
|
signal cb2_edge : std_logic;
|
signal irqb2 : std_logic;
|
signal irqb2 : std_logic := '0';
|
signal cb2_out : std_logic;
|
signal cb2_out : std_logic;
|
|
|
-- 74193 down counter
|
-- 74193 down counter
|
signal timer : std_logic_vector(7 downto 0);
|
signal timer : std_logic_vector(7 downto 0);
|
|
|
begin
|
begin
|
|
|
--------------------------------
|
--------------------------------
|
--
|
--
|
-- read I/O port
|
-- read I/O port
|
--
|
--
|
--------------------------------
|
--------------------------------
|
|
|
pia_read : process( addr, cs,
|
pia_read : process( addr, cs,
|
irqa1, irqa2, irqb1, irqb2,
|
irqa1, irqa2, irqb1, irqb2,
|
porta_ddr, portb_ddr,
|
porta_ddr, portb_ddr,
|
porta_data, portb_data,
|
porta_data, portb_data,
|
porta_ctrl, portb_ctrl,
|
porta_ctrl, portb_ctrl,
|
pa, pb )
|
pa, pb )
|
variable count : integer;
|
variable count : integer;
|
begin
|
begin
|
|
data_out <= "00000000";
|
|
porta_read <= '0';
|
|
portb_read <= '0';
|
|
|
case addr is
|
case addr is
|
when "00" =>
|
when "00" =>
|
for count in 0 to 7 loop
|
for count in 0 to 7 loop
|
if porta_ctrl(2) = '0' then
|
if porta_ctrl(2) = '0' then
|
data_out(count) <= porta_ddr(count);
|
data_out(count) <= porta_ddr(count);
|
porta_read <= '0';
|
porta_read <= '0';
|
else
|
else
|
if porta_ddr(count) = '1' then
|
if porta_ddr(count) = '1' then
|
data_out(count) <= porta_data(count);
|
data_out(count) <= porta_data(count);
|
else
|
else
|
data_out(count) <= pa(count);
|
data_out(count) <= pa(count);
|
end if;
|
end if;
|
porta_read <= cs;
|
porta_read <= cs;
|
end if;
|
end if;
|
end loop;
|
end loop;
|
portb_read <= '0';
|
portb_read <= '0';
|
|
|
when "01" =>
|
when "01" =>
|
data_out <= irqa1 & irqa2 & porta_ctrl;
|
data_out <= irqa1 & irqa2 & porta_ctrl;
|
porta_read <= '0';
|
porta_read <= '0';
|
portb_read <= '0';
|
portb_read <= '0';
|
|
|
when "10" =>
|
when "10" =>
|
for count in 0 to 7 loop
|
for count in 0 to 7 loop
|
if portb_ctrl(2) = '0' then
|
if portb_ctrl(2) = '0' then
|
data_out(count) <= portb_ddr(count);
|
data_out(count) <= portb_ddr(count);
|
portb_read <= '0';
|
portb_read <= '0';
|
else
|
else
|
if portb_ddr(count) = '1' then
|
if portb_ddr(count) = '1' then
|
data_out(count) <= portb_data(count);
|
data_out(count) <= portb_data(count);
|
else
|
else
|
data_out(count) <= pb(count);
|
data_out(count) <= pb(count);
|
end if;
|
end if;
|
portb_read <= cs;
|
portb_read <= cs;
|
end if;
|
end if;
|
end loop;
|
end loop;
|
porta_read <= '0';
|
porta_read <= '0';
|
|
|
when "11" =>
|
when "11" =>
|
data_out <= irqb1 & irqb2 & portb_ctrl;
|
data_out <= irqb1 & irqb2 & portb_ctrl;
|
porta_read <= '0';
|
porta_read <= '0';
|
portb_read <= '0';
|
portb_read <= '0';
|
|
|
when others =>
|
when others =>
|
data_out <= "00000000";
|
null;
|
porta_read <= '0';
|
|
portb_read <= '0';
|
|
|
|
end case;
|
end case;
|
|
|
end process;
|
end process;
|
|
|
---------------------------------
|
---------------------------------
|
--
|
--
|
-- Write I/O ports
|
-- Write I/O ports
|
--
|
--
|
---------------------------------
|
---------------------------------
|
|
|
pia_write : process( clk, rst, addr, cs, rw, data_in,
|
pia_write : process( clk, rst, addr, cs, rw, data_in,
|
porta_ctrl, portb_ctrl,
|
porta_ctrl, portb_ctrl,
|
porta_data, portb_data,
|
porta_data, portb_data,
|
porta_ctrl, portb_ctrl,
|
porta_ctrl, portb_ctrl,
|
porta_ddr, portb_ddr )
|
porta_ddr, portb_ddr )
|
begin
|
begin
|
if rst = '1' then
|
if rst = '1' then
|
porta_ddr <= "00000000";
|
porta_ddr <= "00000000";
|
porta_data <= "00000000";
|
porta_data <= "00000000";
|
porta_ctrl <= "000000";
|
porta_ctrl <= "000000";
|
portb_ddr <= "00000000";
|
portb_ddr <= "00000000";
|
portb_data <= "00000000";
|
portb_data <= "00000000";
|
portb_ctrl <= "000000";
|
portb_ctrl <= "000000";
|
portb_write <= '0';
|
portb_write <= '0';
|
elsif clk'event and clk = '1' then
|
elsif clk'event and clk = '1' then
|
if cs = '1' and rw = '0' then
|
if cs = '1' and rw = '0' then
|
case addr is
|
case addr is
|
when "00" =>
|
when "00" =>
|
if porta_ctrl(2) = '0' then
|
if porta_ctrl(2) = '0' then
|
porta_ddr <= data_in;
|
porta_ddr <= data_in;
|
porta_data <= porta_data;
|
porta_data <= porta_data;
|
else
|
else
|
porta_ddr <= porta_ddr;
|
porta_ddr <= porta_ddr;
|
porta_data <= data_in;
|
porta_data <= data_in;
|
end if;
|
end if;
|
porta_ctrl <= porta_ctrl;
|
porta_ctrl <= porta_ctrl;
|
portb_ddr <= portb_ddr;
|
portb_ddr <= portb_ddr;
|
portb_data <= portb_data;
|
portb_data <= portb_data;
|
portb_ctrl <= portb_ctrl;
|
portb_ctrl <= portb_ctrl;
|
portb_write <= '0';
|
portb_write <= '0';
|
when "01" =>
|
when "01" =>
|
porta_ddr <= porta_ddr;
|
porta_ddr <= porta_ddr;
|
porta_data <= porta_data;
|
porta_data <= porta_data;
|
porta_ctrl <= data_in(5 downto 0);
|
porta_ctrl <= data_in(5 downto 0);
|
portb_ddr <= portb_ddr;
|
portb_ddr <= portb_ddr;
|
portb_data <= portb_data;
|
portb_data <= portb_data;
|
portb_ctrl <= portb_ctrl;
|
portb_ctrl <= portb_ctrl;
|
portb_write <= '0';
|
portb_write <= '0';
|
when "10" =>
|
when "10" =>
|
porta_ddr <= porta_ddr;
|
porta_ddr <= porta_ddr;
|
porta_data <= porta_data;
|
porta_data <= porta_data;
|
porta_ctrl <= porta_ctrl;
|
porta_ctrl <= porta_ctrl;
|
if portb_ctrl(2) = '0' then
|
if portb_ctrl(2) = '0' then
|
portb_ddr <= data_in;
|
portb_ddr <= data_in;
|
portb_data <= portb_data;
|
portb_data <= portb_data;
|
portb_write <= '0';
|
portb_write <= '0';
|
else
|
else
|
portb_ddr <= portb_ddr;
|
portb_ddr <= portb_ddr;
|
portb_data <= data_in;
|
portb_data <= data_in;
|
portb_write <= '1';
|
portb_write <= '1';
|
end if;
|
end if;
|
portb_ctrl <= portb_ctrl;
|
portb_ctrl <= portb_ctrl;
|
when "11" =>
|
when "11" =>
|
porta_ddr <= porta_ddr;
|
porta_ddr <= porta_ddr;
|
porta_data <= porta_data;
|
porta_data <= porta_data;
|
porta_ctrl <= porta_ctrl;
|
porta_ctrl <= porta_ctrl;
|
portb_ddr <= portb_ddr;
|
portb_ddr <= portb_ddr;
|
portb_data <= portb_data;
|
portb_data <= portb_data;
|
portb_ctrl <= data_in(5 downto 0);
|
portb_ctrl <= data_in(5 downto 0);
|
portb_write <= '0';
|
portb_write <= '0';
|
when others =>
|
when others =>
|
porta_ddr <= porta_ddr;
|
porta_ddr <= porta_ddr;
|
porta_data <= porta_data;
|
porta_data <= porta_data;
|
porta_ctrl <= porta_ctrl;
|
porta_ctrl <= porta_ctrl;
|
portb_ddr <= portb_ddr;
|
portb_ddr <= portb_ddr;
|
portb_data <= portb_data;
|
portb_data <= portb_data;
|
portb_ctrl <= portb_ctrl;
|
portb_ctrl <= portb_ctrl;
|
portb_write <= '0';
|
portb_write <= '0';
|
end case;
|
end case;
|
else
|
else
|
porta_ddr <= porta_ddr;
|
porta_ddr <= porta_ddr;
|
porta_data <= porta_data;
|
porta_data <= porta_data;
|
porta_ctrl <= porta_ctrl;
|
porta_ctrl <= porta_ctrl;
|
portb_data <= portb_data;
|
portb_data <= portb_data;
|
portb_ddr <= portb_ddr;
|
portb_ddr <= portb_ddr;
|
portb_ctrl <= portb_ctrl;
|
portb_ctrl <= portb_ctrl;
|
portb_write <= '0';
|
portb_write <= '0';
|
end if;
|
end if;
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
---------------------------------
|
---------------------------------
|
--
|
--
|
-- CA1 Edge detect
|
-- CA1 Edge detect
|
--
|
--
|
---------------------------------
|
---------------------------------
|
ca1_input : process( clk, rst, ca1, ca1_del,
|
ca1_input : process( clk, rst, ca1, ca1_del,
|
ca1_rise, ca1_fall, ca1_edge,
|
ca1_rise, ca1_fall, ca1_edge,
|
irqa1, porta_ctrl, porta_read )
|
irqa1, porta_ctrl, porta_read )
|
begin
|
begin
|
if rst = '1' then
|
if rst = '1' then
|
ca1_del <= '0';
|
ca1_del <= '0';
|
ca1_rise <= '0';
|
ca1_rise <= '0';
|
ca1_fall <= '0';
|
ca1_fall <= '0';
|
ca1_edge <= '0';
|
ca1_edge <= '0';
|
irqa1 <= '0';
|
irqa1 <= '0';
|
elsif clk'event and clk = '0' then
|
elsif clk'event and clk = '0' then
|
ca1_del <= ca1;
|
ca1_del <= ca1;
|
ca1_rise <= (not ca1_del) and ca1;
|
ca1_rise <= (not ca1_del) and ca1;
|
ca1_fall <= ca1_del and (not ca1);
|
ca1_fall <= ca1_del and (not ca1);
|
if ca1_edge = '1' then
|
if ca1_edge = '1' then
|
irqa1 <= '1';
|
irqa1 <= '1';
|
elsif porta_read = '1' then
|
elsif porta_read = '1' then
|
irqa1 <= '0';
|
irqa1 <= '0';
|
else
|
else
|
irqa1 <= irqa1;
|
irqa1 <= irqa1;
|
end if;
|
end if;
|
end if;
|
end if;
|
|
|
if porta_ctrl(1) = '0' then
|
if porta_ctrl(1) = '0' then
|
ca1_edge <= ca1_fall;
|
ca1_edge <= ca1_fall;
|
else
|
else
|
ca1_edge <= ca1_rise;
|
ca1_edge <= ca1_rise;
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
---------------------------------
|
---------------------------------
|
--
|
--
|
-- CA2 Edge detect
|
-- CA2 Edge detect
|
--
|
--
|
---------------------------------
|
---------------------------------
|
ca2_input : process( clk, rst, ca2, ca2_del,
|
ca2_input : process( clk, rst, ca2, ca2_del,
|
ca2_rise, ca2_fall, ca2_edge,
|
ca2_rise, ca2_fall, ca2_edge,
|
irqa2, porta_ctrl, porta_read )
|
irqa2, porta_ctrl, porta_read )
|
begin
|
begin
|
if rst = '1' then
|
if rst = '1' then
|
ca2_del <= '0';
|
ca2_del <= '0';
|
ca2_rise <= '0';
|
ca2_rise <= '0';
|
ca2_fall <= '0';
|
ca2_fall <= '0';
|
ca2_edge <= '0';
|
ca2_edge <= '0';
|
irqa2 <= '0';
|
irqa2 <= '0';
|
elsif clk'event and clk = '0' then
|
elsif clk'event and clk = '0' then
|
ca2_del <= ca2;
|
ca2_del <= ca2;
|
ca2_rise <= (not ca2_del) and ca2;
|
ca2_rise <= (not ca2_del) and ca2;
|
ca2_fall <= ca2_del and (not ca2);
|
ca2_fall <= ca2_del and (not ca2);
|
if porta_ctrl(5) = '0' and ca2_edge = '1' then
|
if porta_ctrl(5) = '0' and ca2_edge = '1' then
|
irqa2 <= '1';
|
irqa2 <= '1';
|
elsif porta_read = '1' then
|
elsif porta_read = '1' then
|
irqa2 <= '0';
|
irqa2 <= '0';
|
else
|
else
|
irqa2 <= irqa2;
|
irqa2 <= irqa2;
|
end if;
|
end if;
|
end if;
|
end if;
|
|
|
if porta_ctrl(4) = '0' then
|
if porta_ctrl(4) = '0' then
|
ca2_edge <= ca2_fall;
|
ca2_edge <= ca2_fall;
|
else
|
else
|
ca2_edge <= ca2_rise;
|
ca2_edge <= ca2_rise;
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
---------------------------------
|
---------------------------------
|
--
|
--
|
-- CA2 output control
|
-- CA2 output control
|
--
|
--
|
---------------------------------
|
---------------------------------
|
ca2_output : process( clk, rst, porta_ctrl, porta_read, ca1_edge, ca2_out )
|
ca2_output : process( clk, rst, porta_ctrl, porta_read, ca1_edge, ca2_out )
|
begin
|
begin
|
if rst='1' then
|
if rst='1' then
|
ca2_out <= '0';
|
ca2_out <= '0';
|
elsif clk'event and clk='0' then
|
elsif clk'event and clk='0' then
|
case porta_ctrl(5 downto 3) is
|
case porta_ctrl(5 downto 3) is
|
when "100" => -- read PA clears, CA1 edge sets
|
when "100" => -- read PA clears, CA1 edge sets
|
if porta_read = '1' then
|
if porta_read = '1' then
|
ca2_out <= '0';
|
ca2_out <= '0';
|
elsif ca1_edge = '1' then
|
elsif ca1_edge = '1' then
|
ca2_out <= '1';
|
ca2_out <= '1';
|
else
|
else
|
ca2_out <= ca2_out;
|
ca2_out <= ca2_out;
|
end if;
|
end if;
|
when "101" => -- read PA clears, E sets
|
when "101" => -- read PA clears, E sets
|
ca2_out <= not porta_read;
|
ca2_out <= not porta_read;
|
when "110" => -- set low
|
when "110" => -- set low
|
ca2_out <= '0';
|
ca2_out <= '0';
|
when "111" => -- set high
|
when "111" => -- set high
|
ca2_out <= '1';
|
ca2_out <= '1';
|
when others => -- no change
|
when others => -- no change
|
ca2_out <= ca2_out;
|
ca2_out <= ca2_out;
|
end case;
|
end case;
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
|
|
---------------------------------
|
---------------------------------
|
--
|
--
|
-- CB1 Edge detect
|
-- CB1 Edge detect
|
--
|
--
|
---------------------------------
|
---------------------------------
|
cb1_input : process( clk, rst, cb1, cb1_del,
|
cb1_input : process( clk, rst, cb1, cb1_del,
|
cb1_rise, cb1_fall, cb1_edge,
|
cb1_rise, cb1_fall, cb1_edge,
|
irqb1, portb_ctrl, portb_read )
|
irqb1, portb_ctrl, portb_read )
|
begin
|
begin
|
if rst = '1' then
|
if rst = '1' then
|
cb1_del <= '0';
|
cb1_del <= '0';
|
cb1_rise <= '0';
|
cb1_rise <= '0';
|
cb1_fall <= '0';
|
cb1_fall <= '0';
|
cb1_edge <= '0';
|
cb1_edge <= '0';
|
irqb1 <= '0';
|
irqb1 <= '0';
|
elsif clk'event and clk = '0' then
|
elsif clk'event and clk = '0' then
|
cb1_del <= cb1;
|
cb1_del <= cb1;
|
cb1_rise <= (not cb1_del) and cb1;
|
cb1_rise <= (not cb1_del) and cb1;
|
cb1_fall <= cb1_del and (not cb1);
|
cb1_fall <= cb1_del and (not cb1);
|
if cb1_edge = '1' then
|
if cb1_edge = '1' then
|
irqb1 <= '1';
|
irqb1 <= '1';
|
elsif portb_read = '1' then
|
elsif portb_read = '1' then
|
irqb1 <= '0';
|
irqb1 <= '0';
|
else
|
else
|
irqb1 <= irqb1;
|
irqb1 <= irqb1;
|
end if;
|
end if;
|
end if;
|
end if;
|
|
|
if portb_ctrl(1) = '0' then
|
if portb_ctrl(1) = '0' then
|
cb1_edge <= cb1_fall;
|
cb1_edge <= cb1_fall;
|
else
|
else
|
cb1_edge <= cb1_rise;
|
cb1_edge <= cb1_rise;
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
---------------------------------
|
---------------------------------
|
--
|
--
|
-- CB2 Edge detect
|
-- CB2 Edge detect
|
--
|
--
|
---------------------------------
|
---------------------------------
|
cb2_input : process( clk, rst, cb2, cb2_del,
|
cb2_input : process( clk, rst, cb2, cb2_del,
|
cb2_rise, cb2_fall, cb2_edge,
|
cb2_rise, cb2_fall, cb2_edge,
|
irqb2, portb_ctrl, portb_read )
|
irqb2, portb_ctrl, portb_read )
|
begin
|
begin
|
if rst = '1' then
|
if rst = '1' then
|
cb2_del <= '0';
|
cb2_del <= '0';
|
cb2_rise <= '0';
|
cb2_rise <= '0';
|
cb2_fall <= '0';
|
cb2_fall <= '0';
|
cb2_edge <= '0';
|
cb2_edge <= '0';
|
irqb2 <= '0';
|
irqb2 <= '0';
|
elsif clk'event and clk = '0' then
|
elsif clk'event and clk = '0' then
|
cb2_del <= cb2;
|
cb2_del <= cb2;
|
cb2_rise <= (not cb2_del) and cb2;
|
cb2_rise <= (not cb2_del) and cb2;
|
cb2_fall <= cb2_del and (not cb2);
|
cb2_fall <= cb2_del and (not cb2);
|
if portb_ctrl(5) = '0' and cb2_edge = '1' then
|
if portb_ctrl(5) = '0' and cb2_edge = '1' then
|
irqb2 <= '1';
|
irqb2 <= '1';
|
elsif portb_read = '1' then
|
elsif portb_read = '1' then
|
irqb2 <= '0';
|
irqb2 <= '0';
|
else
|
else
|
irqb2 <= irqb2;
|
irqb2 <= irqb2;
|
end if;
|
end if;
|
end if;
|
end if;
|
|
|
if portb_ctrl(4) = '0' then
|
if portb_ctrl(4) = '0' then
|
cb2_edge <= cb2_fall;
|
cb2_edge <= cb2_fall;
|
else
|
else
|
cb2_edge <= cb2_rise;
|
cb2_edge <= cb2_rise;
|
end if;
|
end if;
|
|
|
end process;
|
end process;
|
|
|
---------------------------------
|
---------------------------------
|
--
|
--
|
-- CB2 output control
|
-- CB2 output control
|
--
|
--
|
---------------------------------
|
---------------------------------
|
cb2_output : process( clk, rst, portb_ctrl, portb_write, cb1_edge, cb2_out )
|
cb2_output : process( clk, rst, portb_ctrl, portb_write, cb1_edge, cb2_out )
|
begin
|
begin
|
if rst='1' then
|
if rst='1' then
|
cb2_out <= '0';
|
cb2_out <= '0';
|
elsif clk'event and clk='0' then
|
elsif clk'event and clk='0' then
|
case portb_ctrl(5 downto 3) is
|
case portb_ctrl(5 downto 3) is
|
when "100" => -- write PB clears, CA1 edge sets
|
when "100" => -- write PB clears, CA1 edge sets
|
if portb_write = '1' then
|
if portb_write = '1' then
|
cb2_out <= '0';
|
cb2_out <= '0';
|
elsif cb1_edge = '1' then
|
elsif cb1_edge = '1' then
|
cb2_out <= '1';
|
cb2_out <= '1';
|
else
|
else
|
cb2_out <= cb2_out;
|
cb2_out <= cb2_out;
|
end if;
|
end if;
|
when "101" => -- write PB clears, E sets
|
when "101" => -- write PB clears, E sets
|
cb2_out <= not portb_write;
|
cb2_out <= not portb_write;
|
when "110" => -- set low
|
when "110" => -- set low
|
cb2_out <= '0';
|
cb2_out <= '0';
|
when "111" => -- set high
|
when "111" => -- set high
|
cb2_out <= '1';
|
cb2_out <= '1';
|
when others => -- no change
|
when others => -- no change
|
cb2_out <= cb2_out;
|
cb2_out <= cb2_out;
|
end case;
|
end case;
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
---------------------------------
|
---------------------------------
|
--
|
--
|
-- IRQ control
|
-- IRQ control
|
--
|
--
|
---------------------------------
|
---------------------------------
|
pia_irq : process( irqa1, irqa2, irqb1, irqb2, porta_ctrl, portb_ctrl )
|
pia_irq : process( irqa1, irqa2, irqb1, irqb2, porta_ctrl, portb_ctrl )
|
begin
|
begin
|
irqa <= (irqa1 and porta_ctrl(0)) or (irqa2 and porta_ctrl(3));
|
irqa <= (irqa1 and porta_ctrl(0)) or (irqa2 and porta_ctrl(3));
|
irqb <= (irqb1 and portb_ctrl(0)) or (irqb2 and portb_ctrl(3));
|
irqb <= (irqb1 and portb_ctrl(0)) or (irqb2 and portb_ctrl(3));
|
end process;
|
end process;
|
|
|
---------------------------------
|
---------------------------------
|
--
|
--
|
-- 2 x 74193 binary down counter
|
-- 2 x 74193 binary down counter
|
--
|
--
|
---------------------------------
|
---------------------------------
|
--
|
--
|
-- On the reference 6809 board,
|
-- On the reference 6809 board,
|
-- RTI takes one more clock cycle than System09
|
-- RTI takes one more clock cycle than System09
|
-- So subtract 1 from the porta_data preset value.
|
-- So subtract 1 from the porta_data preset value.
|
-- 11th July 2006 John Kent
|
-- 11th July 2006 John Kent
|
-- RTI in CPU09 has been extended by one bus cycle
|
-- RTI in CPU09 has been extended by one bus cycle
|
-- so remove the subtract by one offset on porta_data
|
-- so remove the subtract by one offset on porta_data
|
--
|
--
|
pia_counter : process( clk, timer, porta_data, ca2_out, cb2_out)
|
pia_counter : process( clk, timer, porta_data, ca2_out, cb2_out)
|
begin
|
begin
|
if cb2_out = '1' then
|
if cb2_out = '1' then
|
timer <= "00000000";
|
timer <= "00000000";
|
elsif ca2_out = '0' then
|
elsif ca2_out = '0' then
|
-- timer <= porta_data - "00000001";
|
-- timer <= porta_data - "00000001";
|
timer <= porta_data;
|
timer <= porta_data;
|
elsif clk'event and clk='1' then
|
elsif clk'event and clk='1' then
|
timer <= timer - "00000001";
|
timer <= timer - "00000001";
|
end if;
|
end if;
|
pa <= "00000000";
|
pa <= "00000000";
|
pb <= timer;
|
pb <= timer;
|
ca1 <= timer(7);
|
ca1 <= timer(7);
|
cb1 <= timer(7);
|
cb1 <= timer(7);
|
ca2 <= '0';
|
ca2 <= '0';
|
cb2 <= '0';
|
cb2 <= '0';
|
end process;
|
end process;
|
|
|
end pia_arch;
|
end pia_arch;
|
|
|
|
|
