---------------------------------------------------------------------------------------
|
---------------------------------------------------------------------------------------
|
--
|
--
|
-- Author: John Clayton
|
-- Author: John Clayton
|
-- Date : April 30, 2001
|
-- Date : April 30, 2001
|
-- Update: 4/30/01 copied this file from lcd_2.v (pared down).
|
-- Update: 4/30/01 copied this file from lcd_2.v (pared down).
|
-- Update: 5/24/01 changed the first module from "ps2_keyboard_receiver"
|
-- Update: 5/24/01 changed the first module from "ps2_keyboard_receiver"
|
-- to "ps2_keyboard_interface"
|
-- to "ps2_keyboard_interface"
|
-- Update: 5/29/01 Added input synchronizing flip-flops. Changed state
|
-- Update: 5/29/01 Added input synchronizing flip-flops. Changed state
|
-- encoding (m1) for good operation after part config.
|
-- encoding (m1) for good operation after part config.
|
-- Update: 5/31/01 Added low drive strength and slow transitions to ps2_clk
|
-- Update: 5/31/01 Added low drive strength and slow transitions to ps2_clk
|
-- and ps2_data in the constraints file. Added the signal
|
-- and ps2_data in the constraints file. Added the signal
|
-- "tx_shifting_done" as distinguished from "rx_shifting_done."
|
-- "tx_shifting_done" as distinguished from "rx_shifting_done."
|
-- Debugged the transmitter portion in the lab.
|
-- Debugged the transmitter portion in the lab.
|
-- Update: 6/01/01 Added horizontal tab to the ascii output.
|
-- Update: 6/01/01 Added horizontal tab to the ascii output.
|
-- Update: 6/01/01 Added parameter TRAP_SHIFT_KEYS.
|
-- Update: 6/01/01 Added parameter TRAP_SHIFT_KEYS.
|
-- Update: 6/05/01 Debugged the "debounce" timer functionality.
|
-- Update: 6/05/01 Debugged the "debounce" timer functionality.
|
-- Used 60usec timer as a "watchdog" timeout during
|
-- Used 60usec timer as a "watchdog" timeout during
|
-- receive from the keyboard. This means that a keyboard
|
-- receive from the keyboard. This means that a keyboard
|
-- can now be "hot plugged" into the interface, without
|
-- can now be "hot plugged" into the interface, without
|
-- messing up the bit_count, since the bit_count is reset
|
-- messing up the bit_count, since the bit_count is reset
|
-- to zero during periods of inactivity anyway. This was
|
-- to zero during periods of inactivity anyway. This was
|
-- difficult to debug. I ended up using the logic analyzer,
|
-- difficult to debug. I ended up using the logic analyzer,
|
-- and had to scratch my head quite a bit.
|
-- and had to scratch my head quite a bit.
|
-- Update: 6/06/01 Removed extra comments before the input synchronizing
|
-- Update: 6/06/01 Removed extra comments before the input synchronizing
|
-- flip-flops. Used the correct parameter to size the
|
-- flip-flops. Used the correct parameter to size the
|
-- 5usec_timer_count. Changed the name of this file from
|
-- 5usec_timer_count. Changed the name of this file from
|
-- ps2.v to ps2_keyboard.v
|
-- ps2.v to ps2_keyboard.v
|
-- Update: 6/06/01 Removed "&& q[7:0]" in output_strobe logic. Removed extra
|
-- Update: 6/06/01 Removed "&& q[7:0]" in output_strobe logic. Removed extra
|
-- commented out "else" condition in the shift register and
|
-- commented out "else" condition in the shift register and
|
-- bit counter.
|
-- bit counter.
|
-- Update: 6/07/01 Changed default values for 60usec timer parameters so that
|
-- Update: 6/07/01 Changed default values for 60usec timer parameters so that
|
-- they correspond to 60usec for a 49.152MHz clock.
|
-- they correspond to 60usec for a 49.152MHz clock.
|
--
|
--
|
-- Converted to VHDL: 10 February 2004 - John Kent
|
-- Converted to VHDL: 10 February 2004 - John Kent
|
-- 11 Sept 04 added ctrl key
|
-- 11 Sept 04 added ctrl key
|
-- changed undefined key codes to x"ff"
|
-- changed undefined key codes to x"ff"
|
-- reversed clock polarity
|
-- reversed clock polarity
|
--
|
--
|
-- 18th Oct 04 added ctrl keys to ASCII ROM
|
-- 18th Oct 04 added ctrl keys to ASCII ROM
|
-- added CAPS Lock toggle.
|
-- added CAPS Lock toggle.
|
--
|
--
|
-- 6th Feb 2007 Added Generic Clock parameter
|
-- 6th Feb 2007 Added Generic Clock parameter
|
--
|
--
|
---------------------------------------------------------------------------------------
|
---------------------------------------------------------------------------------------
|
-- Description:
|
-- Description:
|
---------------------------------------------------------------------------------------
|
---------------------------------------------------------------------------------------
|
-- This is a state-machine driven serial-to-parallel and parallel-to-serial
|
-- This is a state-machine driven serial-to-parallel and parallel-to-serial
|
-- interface to the ps2 style keyboard interface. The details of the operation
|
-- interface to the ps2 style keyboard interface. The details of the operation
|
-- of the keyboard interface were obtained from the following website:
|
-- of the keyboard interface were obtained from the following website:
|
--
|
--
|
-- http:--www.beyondlogic.org/keyboard/keybrd.htm
|
-- http:--www.beyondlogic.org/keyboard/keybrd.htm
|
--
|
--
|
-- Some aspects of the keyboard interface are not implemented (e.g, parity
|
-- Some aspects of the keyboard interface are not implemented (e.g, parity
|
-- checking for the receive side, and recognition of the various commands
|
-- checking for the receive side, and recognition of the various commands
|
-- which the keyboard sends out, such as "power on selt test passed," "Error"
|
-- which the keyboard sends out, such as "power on selt test passed," "Error"
|
-- and "Resend.") However, if the user wishes to recognize these reply
|
-- and "Resend.") However, if the user wishes to recognize these reply
|
-- messages, the scan code output can always be used to extend functionality
|
-- messages, the scan code output can always be used to extend functionality
|
-- as desired.
|
-- as desired.
|
--
|
--
|
-- Note that the "Extended" (0xE0) and "Released" (0xF0) codes are recognized.
|
-- Note that the "Extended" (0xE0) and "Released" (0xF0) codes are recognized.
|
-- The rx interface provides separate indicator flags for these two conditions
|
-- The rx interface provides separate indicator flags for these two conditions
|
-- with every valid character scan code which it provides. The shift keys are
|
-- with every valid character scan code which it provides. The shift keys are
|
-- also trapped by the interface, in order to provide correct uppercase ASCII
|
-- also trapped by the interface, in order to provide correct uppercase ASCII
|
-- characters at the ascii output, although the scan codes for the shift keys
|
-- characters at the ascii output, although the scan codes for the shift keys
|
-- are still provided at the scan code output. So, the left/right ALT keys
|
-- are still provided at the scan code output. So, the left/right ALT keys
|
-- can be differentiated by the presence of the rx_entended signal, while the
|
-- can be differentiated by the presence of the rx_entended signal, while the
|
-- left/right shift keys are differentiable by the different scan codes
|
-- left/right shift keys are differentiable by the different scan codes
|
-- received.
|
-- received.
|
--
|
--
|
-- The interface to the ps2 keyboard uses ps2_clk clock rates of
|
-- The interface to the ps2 keyboard uses ps2_clk clock rates of
|
-- 30-40 kHz, dependent upon the keyboard itself. The rate at which the state
|
-- 30-40 kHz, dependent upon the keyboard itself. The rate at which the state
|
-- machine runs should be at least twice the rate of the ps2_clk, so that the
|
-- machine runs should be at least twice the rate of the ps2_clk, so that the
|
-- states can accurately follow the clock signal itself. Four times
|
-- states can accurately follow the clock signal itself. Four times
|
-- oversampling is better. Say 200kHz at least. The upper limit for clocking
|
-- oversampling is better. Say 200kHz at least. The upper limit for clocking
|
-- the state machine will undoubtedly be determined by delays in the logic
|
-- the state machine will undoubtedly be determined by delays in the logic
|
-- which decodes the scan codes into ASCII equivalents. The maximum speed
|
-- which decodes the scan codes into ASCII equivalents. The maximum speed
|
-- will be most likely many megahertz, depending upon target technology.
|
-- will be most likely many megahertz, depending upon target technology.
|
-- In order to run the state machine extremely fast, synchronizing flip-flops
|
-- In order to run the state machine extremely fast, synchronizing flip-flops
|
-- have been added to the ps2_clk and ps2_data inputs of the state machine.
|
-- have been added to the ps2_clk and ps2_data inputs of the state machine.
|
-- This avoids poor performance related to slow transitions of the inputs.
|
-- This avoids poor performance related to slow transitions of the inputs.
|
--
|
--
|
-- Because this is a bi-directional interface, while reading from the keyboard
|
-- Because this is a bi-directional interface, while reading from the keyboard
|
-- the ps2_clk and ps2_data lines are used as inputs. While writing to the
|
-- the ps2_clk and ps2_data lines are used as inputs. While writing to the
|
-- keyboard, however (which may be done at any time. If writing interrupts a
|
-- keyboard, however (which may be done at any time. If writing interrupts a
|
-- read from the keyboard, the keyboard will buffer up its data, and send
|
-- read from the keyboard, the keyboard will buffer up its data, and send
|
-- it later) both the ps2_clk and ps2_data lines are occasionally pulled low,
|
-- it later) both the ps2_clk and ps2_data lines are occasionally pulled low,
|
-- and pullup resistors are used to bring the lines high again, by setting
|
-- and pullup resistors are used to bring the lines high again, by setting
|
-- the drivers to high impedance state.
|
-- the drivers to high impedance state.
|
--
|
--
|
-- The tx interface, for writing to the keyboard, does not provide any special
|
-- The tx interface, for writing to the keyboard, does not provide any special
|
-- pre-processing. It simply transmits the 8-bit command value to the
|
-- pre-processing. It simply transmits the 8-bit command value to the
|
-- keyboard.
|
-- keyboard.
|
--
|
--
|
-- Pullups MUST BE USED on the ps2_clk and ps2_data lines for this design,
|
-- Pullups MUST BE USED on the ps2_clk and ps2_data lines for this design,
|
-- whether they be internal to an FPGA I/O pad, or externally placed.
|
-- whether they be internal to an FPGA I/O pad, or externally placed.
|
-- If internal pullups are used, they may be fairly weak, causing bounces
|
-- If internal pullups are used, they may be fairly weak, causing bounces
|
-- due to crosstalk, etc. There is a "debounce timer" implemented in order
|
-- due to crosstalk, etc. There is a "debounce timer" implemented in order
|
-- to eliminate erroneous state transitions which would occur based on bounce.
|
-- to eliminate erroneous state transitions which would occur based on bounce.
|
--
|
--
|
-- Parameters are provided in order to configure and appropriately size the
|
-- Parameters are provided in order to configure and appropriately size the
|
-- counter of a 60 microsecond timer used in the transmitter, depending on
|
-- counter of a 60 microsecond timer used in the transmitter, depending on
|
-- the clock frequency used. The 60 microsecond period is guaranteed to be
|
-- the clock frequency used. The 60 microsecond period is guaranteed to be
|
-- more than one period of the ps2_clk_s signal.
|
-- more than one period of the ps2_clk_s signal.
|
--
|
--
|
-- Also, a smaller 5 microsecond timer has been included for "debounce".
|
-- Also, a smaller 5 microsecond timer has been included for "debounce".
|
-- This is used because, with internal pullups on the ps2_clk and ps2_data
|
-- This is used because, with internal pullups on the ps2_clk and ps2_data
|
-- lines, there is some bouncing around which occurs
|
-- lines, there is some bouncing around which occurs
|
--
|
--
|
-- A parameter TRAP_SHIFT_KEYS allows the user to eliminate shift keypresses
|
-- A parameter TRAP_SHIFT_KEYS allows the user to eliminate shift keypresses
|
-- from producing scan codes (along with their "undefined" ASCII equivalents)
|
-- from producing scan codes (along with their "undefined" ASCII equivalents)
|
-- at the output of the interface. If TRAP_SHIFT_KEYS is non-zero, the shift
|
-- at the output of the interface. If TRAP_SHIFT_KEYS is non-zero, the shift
|
-- key status will only be reported by rx_shift_key_on. No ascii or scan
|
-- key status will only be reported by rx_shift_key_on. No ascii or scan
|
-- codes will be reported for the shift keys. This is useful for those who
|
-- codes will be reported for the shift keys. This is useful for those who
|
-- wish to use the ASCII data stream, and who don't want to have to "filter
|
-- wish to use the ASCII data stream, and who don't want to have to "filter
|
-- out" the shift key codes.
|
-- out" the shift key codes.
|
--
|
--
|
--
|
--
|
---------------------------------------------------------------------------------------
|
---------------------------------------------------------------------------------------
|
|
|
library ieee;
|
library ieee;
|
use ieee.std_logic_1164.all;
|
use ieee.std_logic_1164.all;
|
use IEEE.STD_LOGIC_ARITH.ALL;
|
use IEEE.STD_LOGIC_ARITH.ALL;
|
use IEEE.STD_LOGIC_UNSIGNED.ALL;
|
use IEEE.STD_LOGIC_UNSIGNED.ALL;
|
use ieee.numeric_std.all;
|
use ieee.numeric_std.all;
|
|
|
entity ps2_keyboard_interface is
|
entity ps2_keyboard_interface is
|
generic (
|
generic (
|
Frequency_MHz : integer
|
Frequency_MHz : integer
|
);
|
);
|
|
|
port(
|
port(
|
clk : in std_logic;
|
clk : in std_logic;
|
reset : in std_logic;
|
reset : in std_logic;
|
ps2_clk : inout std_logic;
|
ps2_clk : inout std_logic;
|
ps2_data : inout std_logic;
|
ps2_data : inout std_logic;
|
rx_extended : out std_logic;
|
rx_extended : out std_logic;
|
rx_released : out std_logic;
|
rx_released : out std_logic;
|
rx_shift_key_on : out std_logic;
|
rx_shift_key_on : out std_logic;
|
-- rx_scan_code : out std_logic_vector(7 downto 0);
|
-- rx_scan_code : out std_logic_vector(7 downto 0);
|
rx_ascii : out std_logic_vector(7 downto 0);
|
rx_ascii : out std_logic_vector(7 downto 0);
|
rx_data_ready : out std_logic; -- rx_read_o
|
rx_data_ready : out std_logic; -- rx_read_o
|
rx_read : in std_logic; -- rx_read_ack_i
|
rx_read : in std_logic; -- rx_read_ack_i
|
tx_data : in std_logic_vector(7 downto 0);
|
tx_data : in std_logic_vector(7 downto 0);
|
tx_write : in std_logic;
|
tx_write : in std_logic;
|
tx_write_ack : out std_logic;
|
tx_write_ack : out std_logic;
|
tx_error_no_keyboard_ack : out std_logic
|
tx_error_no_keyboard_ack : out std_logic
|
);
|
);
|
end ps2_keyboard_interface;
|
end ps2_keyboard_interface;
|
|
|
-------------------------------------------------------------------------------
|
-------------------------------------------------------------------------------
|
-- Architecture for ps2 keyboard interface
|
-- Architecture for ps2 keyboard interface
|
-------------------------------------------------------------------------------
|
-------------------------------------------------------------------------------
|
architecture rtl of ps2_keyboard_interface is
|
architecture rtl of ps2_keyboard_interface is
|
-----------------------------------------------------------------------------
|
-----------------------------------------------------------------------------
|
|
|
|
|
constant TOTAL_BITS : integer := 11;
|
constant TOTAL_BITS : integer := 11;
|
constant EXTEND_CODE : integer := 16#E0#;
|
constant EXTEND_CODE : integer := 16#E0#;
|
constant RELEASE_CODE : integer := 16#F0#;
|
constant RELEASE_CODE : integer := 16#F0#;
|
constant LEFT_SHIFT : integer := 16#12#;
|
constant LEFT_SHIFT : integer := 16#12#;
|
constant RIGHT_SHIFT : integer := 16#59#;
|
constant RIGHT_SHIFT : integer := 16#59#;
|
constant CTRL_CODE : integer := 16#14#;
|
constant CTRL_CODE : integer := 16#14#;
|
constant CAPS_CODE : integer := 16#58#;
|
constant CAPS_CODE : integer := 16#58#;
|
|
|
|
|
-- constants
|
-- constants
|
|
|
-- The timer value can be up to (2^bits) inclusive.
|
-- The timer value can be up to (2^bits) inclusive.
|
-- Values for 49.152 MHz clock
|
-- Values for 49.152 MHz clock
|
--constant TIMER_60USEC_VALUE_PP : integer := 2950; -- Number of sys_clks for 60usec.
|
--constant TIMER_60USEC_VALUE_PP : integer := 2950; -- Number of sys_clks for 60usec.
|
--constant TIMER_60USEC_BITS_PP : integer := 12; -- Number of bits needed for timer
|
--constant TIMER_60USEC_BITS_PP : integer := 12; -- Number of bits needed for timer
|
--constant TIMER_5USEC_VALUE_PP : integer := 186; -- Number of sys_clks for debounce
|
--constant TIMER_5USEC_VALUE_PP : integer := 186; -- Number of sys_clks for debounce
|
--constant TIMER_5USEC_BITS_PP : integer := 8; -- Number of bits needed for timer
|
--constant TIMER_5USEC_BITS_PP : integer := 8; -- Number of bits needed for timer
|
|
|
-- Values for 12.5 MHz Clock
|
-- Values for 12.5 MHz Clock
|
--constant TIMER_60USEC_VALUE_PP : integer := 750; -- Number of sys_clks for 60usec.
|
--constant TIMER_60USEC_VALUE_PP : integer := 750; -- Number of sys_clks for 60usec.
|
--constant TIMER_60USEC_BITS_PP : integer := 10; -- Number of bits needed for timer
|
--constant TIMER_60USEC_BITS_PP : integer := 10; -- Number of bits needed for timer
|
--constant TIMER_5USEC_VALUE_PP : integer := 62; -- Number of sys_clks for debounce
|
--constant TIMER_5USEC_VALUE_PP : integer := 62; -- Number of sys_clks for debounce
|
--constant TIMER_5USEC_BITS_PP : integer := 6; -- Number of bits needed for timer
|
--constant TIMER_5USEC_BITS_PP : integer := 6; -- Number of bits needed for timer
|
|
|
-- Values for 25 MHz Clock
|
-- Values for 25 MHz Clock
|
--constant TIMER_60USEC_VALUE_PP : integer := 1500; -- Number of sys_clks for 60usec.
|
--constant TIMER_60USEC_VALUE_PP : integer := 1500; -- Number of sys_clks for 60usec.
|
--constant TIMER_60USEC_BITS_PP : integer := 11; -- Number of bits needed for timer
|
--constant TIMER_60USEC_BITS_PP : integer := 11; -- Number of bits needed for timer
|
--constant TIMER_5USEC_VALUE_PP : integer := 125; -- Number of sys_clks for debounce
|
--constant TIMER_5USEC_VALUE_PP : integer := 125; -- Number of sys_clks for debounce
|
--constant TIMER_5USEC_BITS_PP : integer := 7; -- Number of bits needed for timer
|
--constant TIMER_5USEC_BITS_PP : integer := 7; -- Number of bits needed for timer
|
|
|
-- Values for generic Clock up to 50 MHz
|
-- Values for generic Clock up to 50 MHz
|
constant TIMER_60USEC_VALUE_PP : integer := Frequency_MHz * 60; -- Number of sys_clks for 60usec.
|
constant TIMER_60USEC_VALUE_PP : integer := Frequency_MHz * 60; -- Number of sys_clks for 60usec.
|
constant TIMER_60USEC_BITS_PP : integer := 12; -- Number of bits needed for timer
|
constant TIMER_60USEC_BITS_PP : integer := 12; -- Number of bits needed for timer
|
constant TIMER_5USEC_VALUE_PP : integer := Frequency_MHz * 5; -- Number of sys_clks for debounce
|
constant TIMER_5USEC_VALUE_PP : integer := Frequency_MHz * 5; -- Number of sys_clks for debounce
|
constant TIMER_5USEC_BITS_PP : integer := 8; -- Number of bits needed for timer
|
constant TIMER_5USEC_BITS_PP : integer := 8; -- Number of bits needed for timer
|
|
|
constant TRAP_SHIFT_KEYS_PP : integer := 1; -- Default: No shift key trap.
|
constant TRAP_SHIFT_KEYS_PP : integer := 1; -- Default: No shift key trap.
|
|
|
-- State encodings, provided as constants
|
-- State encodings, provided as constants
|
-- for flexibility to the one instantiating the module.
|
-- for flexibility to the one instantiating the module.
|
-- In general, the default values need not be changed.
|
-- In general, the default values need not be changed.
|
|
|
-- State "m1_rx_clk_l" has been chosen on purpose. Since the input
|
-- State "m1_rx_clk_l" has been chosen on purpose. Since the input
|
-- synchronizing flip-flops initially contain zero, it takes one clk
|
-- synchronizing flip-flops initially contain zero, it takes one clk
|
-- for them to update to reflect the actual (idle = high) status of
|
-- for them to update to reflect the actual (idle = high) status of
|
-- the I/O lines from the keyboard. Therefore, choosing 0 for m1_rx_clk_l
|
-- the I/O lines from the keyboard. Therefore, choosing 0 for m1_rx_clk_l
|
-- allows the state machine to transition to m1_rx_clk_h when the true
|
-- allows the state machine to transition to m1_rx_clk_h when the true
|
-- values of the input signals become present at the outputs of the
|
-- values of the input signals become present at the outputs of the
|
-- synchronizing flip-flops. This initial transition is harmless, and it
|
-- synchronizing flip-flops. This initial transition is harmless, and it
|
-- eliminates the need for a "reset" pulse before the interface can operate.
|
-- eliminates the need for a "reset" pulse before the interface can operate.
|
|
|
type m1_type is ( m1_rx_clk_h, m1_rx_clk_l,
|
type m1_type is ( m1_rx_clk_h, m1_rx_clk_l,
|
m1_tx_wait_clk_h, m1_tx_force_clk_l,
|
m1_tx_wait_clk_h, m1_tx_force_clk_l,
|
m1_tx_clk_h, m1_tx_clk_l,
|
m1_tx_clk_h, m1_tx_clk_l,
|
m1_tx_wait_keyboard_ack, m1_tx_done_recovery,
|
m1_tx_wait_keyboard_ack, m1_tx_done_recovery,
|
m1_tx_error_no_keyboard_ack, m1_tx_rising_edge_marker,
|
m1_tx_error_no_keyboard_ack, m1_tx_rising_edge_marker,
|
m1_tx_first_wait_clk_h, m1_tx_first_wait_clk_l, m1_tx_reset_timer,
|
m1_tx_first_wait_clk_h, m1_tx_first_wait_clk_l, m1_tx_reset_timer,
|
m1_rx_falling_edge_marker, m1_rx_rising_edge_marker );
|
m1_rx_falling_edge_marker, m1_rx_rising_edge_marker );
|
|
|
-- Internal signal declarations
|
-- Internal signal declarations
|
signal timer_60usec_done : std_logic;
|
signal timer_60usec_done : std_logic;
|
signal timer_5usec_done : std_logic;
|
signal timer_5usec_done : std_logic;
|
signal extended : std_logic;
|
signal extended : std_logic;
|
signal released : std_logic;
|
signal released : std_logic;
|
signal shift_key_on : std_logic;
|
signal shift_key_on : std_logic;
|
signal ctrl_key_on : std_logic;
|
signal ctrl_key_on : std_logic;
|
signal caps_key_on : std_logic;
|
signal caps_key_on : std_logic;
|
|
|
-- NOTE: These two signals used to be one. They
|
-- NOTE: These two signals used to be one. They
|
-- were split into two signals because of
|
-- were split into two signals because of
|
-- shift key trapping. With shift key
|
-- shift key trapping. With shift key
|
-- trapping, no event is generated externally,
|
-- trapping, no event is generated externally,
|
-- but the "hold" data must still be cleared
|
-- but the "hold" data must still be cleared
|
-- anyway regardless, in preparation for the
|
-- anyway regardless, in preparation for the
|
-- next scan codes.
|
-- next scan codes.
|
signal rx_output_event : std_logic; -- Used only to clear: hold_released, hold_extended
|
signal rx_output_event : std_logic; -- Used only to clear: hold_released, hold_extended
|
signal rx_output_strobe : std_logic; -- Used to produce the actual output.
|
signal rx_output_strobe : std_logic; -- Used to produce the actual output.
|
|
|
signal tx_parity_bit : std_logic;
|
signal tx_parity_bit : std_logic;
|
signal rx_shifting_done : std_logic;
|
signal rx_shifting_done : std_logic;
|
signal tx_shifting_done : std_logic;
|
signal tx_shifting_done : std_logic;
|
signal shift_key_plus_code: std_logic_vector(8 downto 0);
|
signal shift_key_plus_code: std_logic_vector(8 downto 0);
|
|
|
signal q : std_logic_vector(TOTAL_BITS-1 downto 0);
|
signal q : std_logic_vector(TOTAL_BITS-1 downto 0);
|
signal m1_state : m1_type;
|
signal m1_state : m1_type;
|
signal m1_next_state : m1_type;
|
signal m1_next_state : m1_type;
|
signal bit_count : std_logic_vector(3 downto 0);
|
signal bit_count : std_logic_vector(3 downto 0);
|
signal enable_timer_60usec: std_logic;
|
signal enable_timer_60usec: std_logic;
|
signal enable_timer_5usec : std_logic;
|
signal enable_timer_5usec : std_logic;
|
signal timer_60usec_count : std_logic_vector(TIMER_60USEC_BITS_PP-1 downto 0);
|
signal timer_60usec_count : std_logic_vector(TIMER_60USEC_BITS_PP-1 downto 0);
|
signal timer_5usec_count : std_logic_vector(TIMER_5USEC_BITS_PP-1 downto 0);
|
signal timer_5usec_count : std_logic_vector(TIMER_5USEC_BITS_PP-1 downto 0);
|
signal ascii : std_logic_vector(7 downto 0); -- "REG" type only because a case statement is used.
|
signal ascii : std_logic_vector(7 downto 0); -- "REG" type only because a case statement is used.
|
signal left_shift_key : std_logic;
|
signal left_shift_key : std_logic;
|
signal right_shift_key : std_logic;
|
signal right_shift_key : std_logic;
|
signal hold_extended : std_logic; -- Holds prior value, cleared at rx_output_strobe
|
signal hold_extended : std_logic; -- Holds prior value, cleared at rx_output_strobe
|
signal hold_released : std_logic; -- Holds prior value, cleared at rx_output_strobe
|
signal hold_released : std_logic; -- Holds prior value, cleared at rx_output_strobe
|
signal ps2_clk_s : std_logic; -- Synchronous version of this input
|
signal ps2_clk_s : std_logic; -- Synchronous version of this input
|
signal ps2_data_s : std_logic; -- Synchronous version of this input
|
signal ps2_data_s : std_logic; -- Synchronous version of this input
|
signal ps2_clk_hi_z : std_logic; -- Without keyboard, high Z equals 1 due to pullups.
|
signal ps2_clk_hi_z : std_logic; -- Without keyboard, high Z equals 1 due to pullups.
|
signal ps2_data_hi_z : std_logic; -- Without keyboard, high Z equals 1 due to pullups.
|
signal ps2_data_hi_z : std_logic; -- Without keyboard, high Z equals 1 due to pullups.
|
signal tx_write_ack_o : std_logic;
|
signal tx_write_ack_o : std_logic;
|
|
|
--
|
--
|
-- key lookup table
|
-- key lookup table
|
--
|
--
|
component keymap_rom
|
component keymap_rom
|
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 (8 downto 0);
|
addr : in std_logic_vector (8 downto 0);
|
rdata : out std_logic_vector (7 downto 0);
|
rdata : out std_logic_vector (7 downto 0);
|
wdata : in std_logic_vector (7 downto 0)
|
wdata : in std_logic_vector (7 downto 0)
|
);
|
);
|
end component;
|
end component;
|
|
|
begin
|
begin
|
|
|
my_key_map : keymap_rom
|
my_key_map : keymap_rom
|
Port map (
|
Port map (
|
clk => clk,
|
clk => clk,
|
rst => reset,
|
rst => reset,
|
cs => '1',
|
cs => '1',
|
rw => '1',
|
rw => '1',
|
addr => shift_key_plus_code,
|
addr => shift_key_plus_code,
|
rdata => ascii,
|
rdata => ascii,
|
wdata => "00000000"
|
wdata => "00000000"
|
);
|
);
|
|
|
----------------------------------------------------------------------------
|
----------------------------------------------------------------------------
|
-- Module code
|
-- Module code
|
-- assign ps2_clk = ps2_clk_hi_z?1'bZ:1'b0;
|
-- assign ps2_clk = ps2_clk_hi_z?1'bZ:1'b0;
|
-- assign ps2_data = ps2_data_hi_z?1'bZ:1'b0;
|
-- assign ps2_data = ps2_data_hi_z?1'bZ:1'b0;
|
--
|
--
|
ps2_direction : process( ps2_clk_hi_z, ps2_data_hi_z )
|
ps2_direction : process( ps2_clk_hi_z, ps2_data_hi_z )
|
begin
|
begin
|
if( ps2_clk_hi_z = '1' ) then
|
if( ps2_clk_hi_z = '1' ) then
|
ps2_clk <= 'Z';
|
ps2_clk <= 'Z';
|
else
|
else
|
ps2_clk <= '0';
|
ps2_clk <= '0';
|
end if;
|
end if;
|
if( ps2_data_hi_z = '1' ) then
|
if( ps2_data_hi_z = '1' ) then
|
ps2_data <= 'Z';
|
ps2_data <= 'Z';
|
else
|
else
|
ps2_data <= '0';
|
ps2_data <= '0';
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
-- Input "synchronizing" logic -- synchronizes the inputs to the state
|
-- Input "synchronizing" logic -- synchronizes the inputs to the state
|
-- machine clock, thus avoiding errors related to
|
-- machine clock, thus avoiding errors related to
|
-- spurious state machine transitions.
|
-- spurious state machine transitions.
|
ps2_synch : process(clk, ps2_clk, ps2_data)
|
ps2_synch : process(clk, ps2_clk, ps2_data)
|
begin
|
begin
|
if clk'event and clk='0' then
|
if clk'event and clk='0' then
|
ps2_clk_s <= ps2_clk;
|
ps2_clk_s <= ps2_clk;
|
ps2_data_s <= ps2_data;
|
ps2_data_s <= ps2_data;
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
-- State register
|
-- State register
|
m1_state_register : process( clk, reset, m1_state )
|
m1_state_register : process( clk, reset, m1_state )
|
begin
|
begin
|
if clk'event and clk='0' then
|
if clk'event and clk='0' then
|
if (reset = '1') then
|
if (reset = '1') then
|
m1_state <= m1_rx_clk_h;
|
m1_state <= m1_rx_clk_h;
|
else
|
else
|
m1_state <= m1_next_state;
|
m1_state <= m1_next_state;
|
end if;
|
end if;
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
m1_state_logic : process( m1_state, q,
|
m1_state_logic : process( m1_state, q,
|
tx_shifting_done, tx_write,
|
tx_shifting_done, tx_write,
|
ps2_clk_s, ps2_data_s,
|
ps2_clk_s, ps2_data_s,
|
timer_60usec_done, timer_5usec_done )
|
timer_60usec_done, timer_5usec_done )
|
begin
|
begin
|
-- Output signals default to this value, unless changed in a state condition.
|
-- Output signals default to this value, unless changed in a state condition.
|
ps2_clk_hi_z <= '1';
|
ps2_clk_hi_z <= '1';
|
ps2_data_hi_z <= '1';
|
ps2_data_hi_z <= '1';
|
tx_error_no_keyboard_ack <= '0';
|
tx_error_no_keyboard_ack <= '0';
|
enable_timer_60usec <= '0';
|
enable_timer_60usec <= '0';
|
enable_timer_5usec <= '0';
|
enable_timer_5usec <= '0';
|
|
|
case (m1_state) is
|
case (m1_state) is
|
when m1_rx_clk_h =>
|
when m1_rx_clk_h =>
|
enable_timer_60usec <= '1';
|
enable_timer_60usec <= '1';
|
if (tx_write = '1') then
|
if (tx_write = '1') then
|
m1_next_state <= m1_tx_reset_timer;
|
m1_next_state <= m1_tx_reset_timer;
|
elsif (ps2_clk_s = '0') then
|
elsif (ps2_clk_s = '0') then
|
m1_next_state <= m1_rx_falling_edge_marker;
|
m1_next_state <= m1_rx_falling_edge_marker;
|
else
|
else
|
m1_next_state <= m1_rx_clk_h;
|
m1_next_state <= m1_rx_clk_h;
|
end if;
|
end if;
|
|
|
when m1_rx_falling_edge_marker =>
|
when m1_rx_falling_edge_marker =>
|
enable_timer_60usec <= '0';
|
enable_timer_60usec <= '0';
|
m1_next_state <= m1_rx_clk_l;
|
m1_next_state <= m1_rx_clk_l;
|
|
|
when m1_rx_clk_l =>
|
when m1_rx_clk_l =>
|
enable_timer_60usec <= '1';
|
enable_timer_60usec <= '1';
|
if (tx_write = '1') then
|
if (tx_write = '1') then
|
m1_next_state <= m1_tx_reset_timer;
|
m1_next_state <= m1_tx_reset_timer;
|
elsif (ps2_clk_s = '1') then
|
elsif (ps2_clk_s = '1') then
|
m1_next_state <= m1_rx_rising_edge_marker;
|
m1_next_state <= m1_rx_rising_edge_marker;
|
else
|
else
|
m1_next_state <= m1_rx_clk_l;
|
m1_next_state <= m1_rx_clk_l;
|
end if;
|
end if;
|
|
|
when m1_rx_rising_edge_marker =>
|
when m1_rx_rising_edge_marker =>
|
enable_timer_60usec <= '0';
|
enable_timer_60usec <= '0';
|
m1_next_state <= m1_rx_clk_h;
|
m1_next_state <= m1_rx_clk_h;
|
|
|
when m1_tx_reset_timer =>
|
when m1_tx_reset_timer =>
|
enable_timer_60usec <= '0';
|
enable_timer_60usec <= '0';
|
m1_next_state <= m1_tx_force_clk_l;
|
m1_next_state <= m1_tx_force_clk_l;
|
|
|
when m1_tx_force_clk_l =>
|
when m1_tx_force_clk_l =>
|
enable_timer_60usec <= '1';
|
enable_timer_60usec <= '1';
|
ps2_clk_hi_z <= '0'; -- Force the ps2_clk line low.
|
ps2_clk_hi_z <= '0'; -- Force the ps2_clk line low.
|
if (timer_60usec_done = '1') then
|
if (timer_60usec_done = '1') then
|
m1_next_state <= m1_tx_first_wait_clk_h;
|
m1_next_state <= m1_tx_first_wait_clk_h;
|
else
|
else
|
m1_next_state <= m1_tx_force_clk_l;
|
m1_next_state <= m1_tx_force_clk_l;
|
end if;
|
end if;
|
|
|
when m1_tx_first_wait_clk_h =>
|
when m1_tx_first_wait_clk_h =>
|
enable_timer_5usec <= '1';
|
enable_timer_5usec <= '1';
|
ps2_data_hi_z <= '0'; -- Start bit.
|
ps2_data_hi_z <= '0'; -- Start bit.
|
if (ps2_clk_s = '0') and (timer_5usec_done = '1') then
|
if (ps2_clk_s = '0') and (timer_5usec_done = '1') then
|
m1_next_state <= m1_tx_clk_l;
|
m1_next_state <= m1_tx_clk_l;
|
else
|
else
|
m1_next_state <= m1_tx_first_wait_clk_h;
|
m1_next_state <= m1_tx_first_wait_clk_h;
|
end if;
|
end if;
|
|
|
-- This state must be included because the device might possibly
|
-- This state must be included because the device might possibly
|
-- delay for up to 10 milliseconds before beginning its clock pulses.
|
-- delay for up to 10 milliseconds before beginning its clock pulses.
|
-- During that waiting time, we cannot drive the data (q[0]) because it
|
-- During that waiting time, we cannot drive the data (q[0]) because it
|
-- is possibly 1, which would cause the keyboard to abort its receive
|
-- is possibly 1, which would cause the keyboard to abort its receive
|
-- and the expected clocks would then never be generated.
|
-- and the expected clocks would then never be generated.
|
when m1_tx_first_wait_clk_l =>
|
when m1_tx_first_wait_clk_l =>
|
ps2_data_hi_z <= '0';
|
ps2_data_hi_z <= '0';
|
if (ps2_clk_s = '0') then
|
if (ps2_clk_s = '0') then
|
m1_next_state <= m1_tx_clk_l;
|
m1_next_state <= m1_tx_clk_l;
|
else
|
else
|
m1_next_state <= m1_tx_first_wait_clk_l;
|
m1_next_state <= m1_tx_first_wait_clk_l;
|
end if;
|
end if;
|
|
|
when m1_tx_wait_clk_h =>
|
when m1_tx_wait_clk_h =>
|
enable_timer_5usec <= '1';
|
enable_timer_5usec <= '1';
|
ps2_data_hi_z <= q(0);
|
ps2_data_hi_z <= q(0);
|
if (ps2_clk_s = '1') and (timer_5usec_done = '1') then
|
if (ps2_clk_s = '1') and (timer_5usec_done = '1') then
|
m1_next_state <= m1_tx_rising_edge_marker;
|
m1_next_state <= m1_tx_rising_edge_marker;
|
else
|
else
|
m1_next_state <= m1_tx_wait_clk_h;
|
m1_next_state <= m1_tx_wait_clk_h;
|
end if;
|
end if;
|
|
|
when m1_tx_rising_edge_marker =>
|
when m1_tx_rising_edge_marker =>
|
ps2_data_hi_z <= q(0);
|
ps2_data_hi_z <= q(0);
|
m1_next_state <= m1_tx_clk_h;
|
m1_next_state <= m1_tx_clk_h;
|
|
|
when m1_tx_clk_h =>
|
when m1_tx_clk_h =>
|
ps2_data_hi_z <= q(0);
|
ps2_data_hi_z <= q(0);
|
if (tx_shifting_done = '1') then
|
if (tx_shifting_done = '1') then
|
m1_next_state <= m1_tx_wait_keyboard_ack;
|
m1_next_state <= m1_tx_wait_keyboard_ack;
|
elsif (ps2_clk_s = '0') then
|
elsif (ps2_clk_s = '0') then
|
m1_next_state <= m1_tx_clk_l;
|
m1_next_state <= m1_tx_clk_l;
|
else
|
else
|
m1_next_state <= m1_tx_clk_h;
|
m1_next_state <= m1_tx_clk_h;
|
end if;
|
end if;
|
|
|
when m1_tx_clk_l =>
|
when m1_tx_clk_l =>
|
ps2_data_hi_z <= q(0);
|
ps2_data_hi_z <= q(0);
|
if (ps2_clk_s = '1') then
|
if (ps2_clk_s = '1') then
|
m1_next_state <= m1_tx_wait_clk_h;
|
m1_next_state <= m1_tx_wait_clk_h;
|
else
|
else
|
m1_next_state <= m1_tx_clk_l;
|
m1_next_state <= m1_tx_clk_l;
|
end if;
|
end if;
|
|
|
when m1_tx_wait_keyboard_ack =>
|
when m1_tx_wait_keyboard_ack =>
|
if (ps2_clk_s = '0') and (ps2_data_s = '1') then
|
if (ps2_clk_s = '0') and (ps2_data_s = '1') then
|
m1_next_state <= m1_tx_error_no_keyboard_ack;
|
m1_next_state <= m1_tx_error_no_keyboard_ack;
|
elsif (ps2_clk_s = '0') and (ps2_data_s = '0') then
|
elsif (ps2_clk_s = '0') and (ps2_data_s = '0') then
|
m1_next_state <= m1_tx_done_recovery;
|
m1_next_state <= m1_tx_done_recovery;
|
else
|
else
|
m1_next_state <= m1_tx_wait_keyboard_ack;
|
m1_next_state <= m1_tx_wait_keyboard_ack;
|
end if;
|
end if;
|
|
|
when m1_tx_done_recovery =>
|
when m1_tx_done_recovery =>
|
if (ps2_clk_s = '1') and (ps2_data_s = '1') then
|
if (ps2_clk_s = '1') and (ps2_data_s = '1') then
|
m1_next_state <= m1_rx_clk_h;
|
m1_next_state <= m1_rx_clk_h;
|
else
|
else
|
m1_next_state <= m1_tx_done_recovery;
|
m1_next_state <= m1_tx_done_recovery;
|
end if;
|
end if;
|
|
|
when m1_tx_error_no_keyboard_ack =>
|
when m1_tx_error_no_keyboard_ack =>
|
tx_error_no_keyboard_ack <= '1';
|
tx_error_no_keyboard_ack <= '1';
|
if (ps2_clk_s = '1') and (ps2_data_s ='1') then
|
if (ps2_clk_s = '1') and (ps2_data_s ='1') then
|
m1_next_state <= m1_rx_clk_h;
|
m1_next_state <= m1_rx_clk_h;
|
else
|
else
|
m1_next_state <= m1_tx_error_no_keyboard_ack;
|
m1_next_state <= m1_tx_error_no_keyboard_ack;
|
end if;
|
end if;
|
|
|
when others =>
|
when others =>
|
m1_next_state <= m1_rx_clk_h;
|
m1_next_state <= m1_rx_clk_h;
|
end case;
|
end case;
|
end process;
|
end process;
|
|
|
-- This is the bit counter
|
-- This is the bit counter
|
bit_counter: process(clk, reset, m1_state, bit_count )
|
bit_counter: process(clk, reset, m1_state, bit_count )
|
begin
|
begin
|
if clk'event and clk = '0' then
|
if clk'event and clk = '0' then
|
if ( reset = '1' ) or
|
if ( reset = '1' ) or
|
( rx_shifting_done = '1' ) or
|
( rx_shifting_done = '1' ) or
|
(m1_state = m1_tx_wait_keyboard_ack) then -- After tx is done.
|
(m1_state = m1_tx_wait_keyboard_ack) then -- After tx is done.
|
bit_count <= "0000"; -- normal reset
|
bit_count <= "0000"; -- normal reset
|
elsif (timer_60usec_done = '1' ) and
|
elsif (timer_60usec_done = '1' ) and
|
(m1_state = m1_rx_clk_h) and
|
(m1_state = m1_rx_clk_h) and
|
(ps2_clk_s = '1') then
|
(ps2_clk_s = '1') then
|
bit_count <= "0000"; -- rx watchdog timer reset
|
bit_count <= "0000"; -- rx watchdog timer reset
|
elsif (m1_state = m1_rx_falling_edge_marker) or -- increment for rx
|
elsif (m1_state = m1_rx_falling_edge_marker) or -- increment for rx
|
(m1_state = m1_tx_rising_edge_marker) then -- increment for tx
|
(m1_state = m1_tx_rising_edge_marker) then -- increment for tx
|
bit_count <= bit_count + 1;
|
bit_count <= bit_count + 1;
|
end if;
|
end if;
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
assign: process( bit_count, tx_write, tx_write_ack_o, m1_state )
|
assign: process( bit_count, tx_write, tx_write_ack_o, m1_state )
|
begin
|
begin
|
if (bit_count = TOTAL_BITS) then
|
if (bit_count = TOTAL_BITS) then
|
rx_shifting_done <= '1';
|
rx_shifting_done <= '1';
|
else
|
else
|
rx_shifting_done <= '0';
|
rx_shifting_done <= '0';
|
end if;
|
end if;
|
|
|
if (bit_count = (TOTAL_BITS-1)) then
|
if (bit_count = (TOTAL_BITS-1)) then
|
tx_shifting_done <= '1';
|
tx_shifting_done <= '1';
|
else
|
else
|
tx_shifting_done <= '0';
|
tx_shifting_done <= '0';
|
end if;
|
end if;
|
|
|
-- This is the signal which enables loading of the shift register.
|
-- This is the signal which enables loading of the shift register.
|
-- It also indicates "ack" to the device writing to the transmitter.
|
-- It also indicates "ack" to the device writing to the transmitter.
|
if ((tx_write = '1') and (m1_state = m1_rx_clk_h)) or
|
if ((tx_write = '1') and (m1_state = m1_rx_clk_h)) or
|
((tx_write = '1') and (m1_state = m1_rx_clk_l)) then
|
((tx_write = '1') and (m1_state = m1_rx_clk_l)) then
|
tx_write_ack_o <= '1';
|
tx_write_ack_o <= '1';
|
else
|
else
|
tx_write_ack_o <= '0';
|
tx_write_ack_o <= '0';
|
end if;
|
end if;
|
tx_write_ack <= tx_write_ack_o;
|
tx_write_ack <= tx_write_ack_o;
|
end process;
|
end process;
|
|
|
-- This is the ODD parity bit for the transmitted word.
|
-- This is the ODD parity bit for the transmitted word.
|
-- assign tx_parity_bit = ~^tx_data;
|
-- assign tx_parity_bit = ~^tx_data;
|
--
|
--
|
tx_parity_bit <= not( tx_data(7) xor tx_data(6) xor tx_data(5) xor tx_data(4) xor
|
tx_parity_bit <= not( tx_data(7) xor tx_data(6) xor tx_data(5) xor tx_data(4) xor
|
tx_data(3) xor tx_data(2) xor tx_data(1) xor tx_data(0) );
|
tx_data(3) xor tx_data(2) xor tx_data(1) xor tx_data(0) );
|
|
|
-- This is the shift register
|
-- This is the shift register
|
q_shift : process(clk, tx_write_ack_o, tx_parity_bit, tx_data,
|
q_shift : process(clk, tx_write_ack_o, tx_parity_bit, tx_data,
|
m1_state, q, ps2_data_s, rx_shifting_done )
|
m1_state, q, ps2_data_s, rx_shifting_done )
|
begin
|
begin
|
if clk'event and clk='0' then
|
if clk'event and clk='0' then
|
if (reset = '1') then
|
if (reset = '1') then
|
q <= "00000000000";
|
q <= "00000000000";
|
elsif (tx_write_ack_o = '1') then
|
elsif (tx_write_ack_o = '1') then
|
q <= "1" & tx_parity_bit & tx_data & "0";
|
q <= "1" & tx_parity_bit & tx_data & "0";
|
elsif ( (m1_state = m1_rx_falling_edge_marker) or
|
elsif ( (m1_state = m1_rx_falling_edge_marker) or
|
(m1_state = m1_tx_rising_edge_marker) ) then
|
(m1_state = m1_tx_rising_edge_marker) ) then
|
q <= ps2_data_s & q((TOTAL_BITS-1) downto 1);
|
q <= ps2_data_s & q((TOTAL_BITS-1) downto 1);
|
end if;
|
end if;
|
end if;
|
end if;
|
|
|
-- Create the signals which indicate special scan codes received.
|
-- Create the signals which indicate special scan codes received.
|
-- These are the "unlatched versions."
|
-- These are the "unlatched versions."
|
if (q(8 downto 1) = EXTEND_CODE) and (rx_shifting_done = '1') then
|
if (q(8 downto 1) = EXTEND_CODE) and (rx_shifting_done = '1') then
|
extended <= '1';
|
extended <= '1';
|
else
|
else
|
extended <= '0';
|
extended <= '0';
|
end if;
|
end if;
|
if (q(8 downto 1) = RELEASE_CODE) and (rx_shifting_done = '1') then
|
if (q(8 downto 1) = RELEASE_CODE) and (rx_shifting_done = '1') then
|
released <= '1';
|
released <= '1';
|
else
|
else
|
released <= '0';
|
released <= '0';
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
-- This is the 60usec timer counter
|
-- This is the 60usec timer counter
|
timer60usec: process(clk, enable_timer_60usec, timer_60usec_count)
|
timer60usec: process(clk, enable_timer_60usec, timer_60usec_count)
|
begin
|
begin
|
if clk'event and clk = '0' then
|
if clk'event and clk = '0' then
|
if (enable_timer_60usec = '0') then
|
if (enable_timer_60usec = '0') then
|
timer_60usec_count <= (others => '0');
|
timer_60usec_count <= (others => '0');
|
elsif (timer_60usec_done = '0') then
|
elsif (timer_60usec_done = '0') then
|
timer_60usec_count <= timer_60usec_count + 1;
|
timer_60usec_count <= timer_60usec_count + 1;
|
end if;
|
end if;
|
end if;
|
end if;
|
|
|
if (timer_60usec_count = (TIMER_60USEC_VALUE_PP - 1)) then
|
if (timer_60usec_count = (TIMER_60USEC_VALUE_PP - 1)) then
|
timer_60usec_done <= '1';
|
timer_60usec_done <= '1';
|
else
|
else
|
timer_60usec_done <= '0';
|
timer_60usec_done <= '0';
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
-- This is the 5usec timer counter
|
-- This is the 5usec timer counter
|
timer5usec : process(clk, enable_timer_5usec, timer_5usec_count )
|
timer5usec : process(clk, enable_timer_5usec, timer_5usec_count )
|
begin
|
begin
|
if clk'event and clk = '0' then
|
if clk'event and clk = '0' then
|
if (enable_timer_5usec = '0') then
|
if (enable_timer_5usec = '0') then
|
timer_5usec_count <= (others => '0');
|
timer_5usec_count <= (others => '0');
|
elsif (timer_5usec_done = '0') then
|
elsif (timer_5usec_done = '0') then
|
timer_5usec_count <= timer_5usec_count + 1;
|
timer_5usec_count <= timer_5usec_count + 1;
|
end if;
|
end if;
|
end if;
|
end if;
|
|
|
if( timer_5usec_count = (TIMER_5USEC_VALUE_PP - 1)) then
|
if( timer_5usec_count = (TIMER_5USEC_VALUE_PP - 1)) then
|
timer_5usec_done <= '1';
|
timer_5usec_done <= '1';
|
else
|
else
|
timer_5usec_done <= '0';
|
timer_5usec_done <= '0';
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
|
|
-- Store the special scan code status bits
|
-- Store the special scan code status bits
|
-- Not the final output, but an intermediate storage place,
|
-- Not the final output, but an intermediate storage place,
|
-- until the entire set of output data can be assembled.
|
-- until the entire set of output data can be assembled.
|
special_scan : process(clk, reset, rx_output_event, rx_shifting_done, extended, released )
|
special_scan : process(clk, reset, rx_output_event, rx_shifting_done, extended, released )
|
begin
|
begin
|
if clk'event and clk='0' then
|
if clk'event and clk='0' then
|
if (reset = '1') or (rx_output_event = '1') then
|
if (reset = '1') or (rx_output_event = '1') then
|
hold_extended <= '0';
|
hold_extended <= '0';
|
hold_released <= '0';
|
hold_released <= '0';
|
else
|
else
|
if (rx_shifting_done = '1') and (extended = '1') then
|
if (rx_shifting_done = '1') and (extended = '1') then
|
hold_extended <= '1';
|
hold_extended <= '1';
|
end if;
|
end if;
|
if (rx_shifting_done = '1') and (released = '1') then
|
if (rx_shifting_done = '1') and (released = '1') then
|
hold_released <= '1';
|
hold_released <= '1';
|
end if;
|
end if;
|
end if;
|
end if;
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
|
|
-- These bits contain the status of the two shift keys
|
-- These bits contain the status of the two shift keys
|
left_shift_proc : process(clk, reset, q, rx_shifting_done, hold_released )
|
left_shift_proc : process(clk, reset, q, rx_shifting_done, hold_released )
|
begin
|
begin
|
if clk'event and clk = '0' then
|
if clk'event and clk = '0' then
|
if (reset = '1') then
|
if (reset = '1') then
|
left_shift_key <= '0';
|
left_shift_key <= '0';
|
elsif (q(8 downto 1) = LEFT_SHIFT) and
|
elsif (q(8 downto 1) = LEFT_SHIFT) and
|
(rx_shifting_done = '1') and
|
(rx_shifting_done = '1') and
|
(hold_released = '0') then
|
(hold_released = '0') then
|
left_shift_key <= '1';
|
left_shift_key <= '1';
|
elsif (q(8 downto 1) = LEFT_SHIFT) and
|
elsif (q(8 downto 1) = LEFT_SHIFT) and
|
(rx_shifting_done = '1') and
|
(rx_shifting_done = '1') and
|
(hold_released = '1') then
|
(hold_released = '1') then
|
left_shift_key <= '0';
|
left_shift_key <= '0';
|
end if;
|
end if;
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
right_shift_proc : process(clk, reset, q, rx_shifting_done, hold_released )
|
right_shift_proc : process(clk, reset, q, rx_shifting_done, hold_released )
|
begin
|
begin
|
if clk'event and clk = '0' then
|
if clk'event and clk = '0' then
|
if (reset = '1') then
|
if (reset = '1') then
|
right_shift_key <= '0';
|
right_shift_key <= '0';
|
elsif (q(8 downto 1) = RIGHT_SHIFT) and
|
elsif (q(8 downto 1) = RIGHT_SHIFT) and
|
(rx_shifting_done = '1') and
|
(rx_shifting_done = '1') and
|
(hold_released = '0') then
|
(hold_released = '0') then
|
right_shift_key <= '1';
|
right_shift_key <= '1';
|
elsif (q(8 downto 1) = RIGHT_SHIFT) and
|
elsif (q(8 downto 1) = RIGHT_SHIFT) and
|
(rx_shifting_done = '1') and
|
(rx_shifting_done = '1') and
|
(hold_released = '1') then
|
(hold_released = '1') then
|
right_shift_key <= '0';
|
right_shift_key <= '0';
|
end if;
|
end if;
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
shift_key_on <= left_shift_key or right_shift_key;
|
shift_key_on <= left_shift_key or right_shift_key;
|
rx_shift_key_on <= shift_key_on;
|
rx_shift_key_on <= shift_key_on;
|
|
|
--
|
--
|
-- Control keys
|
-- Control keys
|
--
|
--
|
ctrl_proc : process(clk, reset, q, rx_shifting_done, hold_released )
|
ctrl_proc : process(clk, reset, q, rx_shifting_done, hold_released )
|
begin
|
begin
|
if clk'event and clk = '0' then
|
if clk'event and clk = '0' then
|
if (reset = '1') then
|
if (reset = '1') then
|
ctrl_key_on <= '0';
|
ctrl_key_on <= '0';
|
elsif (q(8 downto 1) = CTRL_CODE) and
|
elsif (q(8 downto 1) = CTRL_CODE) and
|
(rx_shifting_done = '1') and
|
(rx_shifting_done = '1') and
|
(hold_released = '0') then
|
(hold_released = '0') then
|
ctrl_key_on <= '1';
|
ctrl_key_on <= '1';
|
elsif (q(8 downto 1) = CTRL_CODE) and
|
elsif (q(8 downto 1) = CTRL_CODE) and
|
(rx_shifting_done = '1') and
|
(rx_shifting_done = '1') and
|
(hold_released = '1') then
|
(hold_released = '1') then
|
ctrl_key_on <= '0';
|
ctrl_key_on <= '0';
|
end if;
|
end if;
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
--
|
--
|
-- Caps lock
|
-- Caps lock
|
--
|
--
|
caps_proc : process(clk, reset, q, rx_shifting_done, hold_released, caps_key_on )
|
caps_proc : process(clk, reset, q, rx_shifting_done, hold_released, caps_key_on )
|
begin
|
begin
|
if clk'event and clk = '0' then
|
if clk'event and clk = '0' then
|
if (reset = '1') then
|
if (reset = '1') then
|
caps_key_on <= '0';
|
caps_key_on <= '0';
|
elsif (q(8 downto 1) = CAPS_CODE) and
|
elsif (q(8 downto 1) = CAPS_CODE) and
|
(rx_shifting_done = '1') and
|
(rx_shifting_done = '1') and
|
(hold_released = '0') then
|
(hold_released = '0') then
|
caps_key_on <= not caps_key_on;
|
caps_key_on <= not caps_key_on;
|
end if;
|
end if;
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
-- Output the special scan code flags, the scan code and the ascii
|
-- Output the special scan code flags, the scan code and the ascii
|
special_scan_proc : process(clk, reset,
|
special_scan_proc : process(clk, reset,
|
hold_extended, hold_released,
|
hold_extended, hold_released,
|
q, ascii, ctrl_key_on )
|
q, ascii, ctrl_key_on )
|
begin
|
begin
|
if clk'event and clk = '0' then
|
if clk'event and clk = '0' then
|
if (reset = '1') then
|
if (reset = '1') then
|
rx_extended <= '0';
|
rx_extended <= '0';
|
rx_released <= '0';
|
rx_released <= '0';
|
-- rx_scan_code <= "00000000";
|
-- rx_scan_code <= "00000000";
|
rx_ascii <= "00000000";
|
rx_ascii <= "00000000";
|
elsif (rx_output_strobe = '1') then
|
elsif (rx_output_strobe = '1') then
|
rx_extended <= hold_extended;
|
rx_extended <= hold_extended;
|
rx_released <= hold_released;
|
rx_released <= hold_released;
|
-- rx_scan_code <= q(8 downto 1);
|
-- rx_scan_code <= q(8 downto 1);
|
elsif ctrl_key_on = '1' then
|
elsif ctrl_key_on = '1' then
|
rx_ascii <= ascii and x"1f";
|
rx_ascii <= ascii and x"1f";
|
else
|
else
|
rx_ascii <= ascii;
|
rx_ascii <= ascii;
|
end if;
|
end if;
|
end if;
|
end if;
|
end process;
|
end process;
|
|
|
-- Store the final rx output data only when all extend and release codes
|
-- Store the final rx output data only when all extend and release codes
|
-- are received and the next (actual key) scan code is also ready.
|
-- are received and the next (actual key) scan code is also ready.
|
-- (the presence of rx_extended or rx_released refers to the
|
-- (the presence of rx_extended or rx_released refers to the
|
-- the current latest scan code received, not the previously latched flags.)
|
-- the current latest scan code received, not the previously latched flags.)
|
|
|
rx_output_proc : process( clk, reset,
|
rx_output_proc : process( clk, reset,
|
rx_shifting_done, rx_output_strobe,
|
rx_shifting_done, rx_output_strobe,
|
extended, released,
|
extended, released,
|
q, ascii, rx_read )
|
q, ascii, rx_read )
|
begin
|
begin
|
if (rx_shifting_done = '1') and (extended = '0') and (released = '0') then
|
if (rx_shifting_done = '1') and (extended = '0') and (released = '0') then
|
rx_output_event <= '1';
|
rx_output_event <= '1';
|
else
|
else
|
rx_output_event <= '0';
|
rx_output_event <= '0';
|
end if;
|
end if;
|
|
|
if clk'event and clk = '0' then
|
if clk'event and clk = '0' then
|
if reset = '1' then
|
if reset = '1' then
|
rx_output_strobe <= '0';
|
rx_output_strobe <= '0';
|
elsif (rx_shifting_done = '1') and
|
elsif (rx_shifting_done = '1') and
|
(rx_output_strobe = '0') and
|
(rx_output_strobe = '0') and
|
(extended = '0') and
|
(extended = '0') and
|
(released = '0') and
|
(released = '0') and
|
(hold_released = '0' ) and
|
(hold_released = '0' ) and
|
(ascii /= x"00" ) then
|
(ascii /= x"00" ) then
|
-- ((TRAP_SHIFT_KEYS_PP = 0) or
|
-- ((TRAP_SHIFT_KEYS_PP = 0) or
|
-- ( (q(8 downto 1) /= RIGHT_SHIFT) and
|
-- ( (q(8 downto 1) /= RIGHT_SHIFT) and
|
-- (q(8 downto 1) /= LEFT_SHIFT) and
|
-- (q(8 downto 1) /= LEFT_SHIFT) and
|
-- (q(8 downto 1) /= CTRL_CODE) ) )then
|
-- (q(8 downto 1) /= CTRL_CODE) ) )then
|
rx_output_strobe <= '1';
|
rx_output_strobe <= '1';
|
elsif rx_read = '1' then
|
elsif rx_read = '1' then
|
rx_output_strobe <= '0';
|
rx_output_strobe <= '0';
|
end if;
|
end if;
|
end if;
|
end if;
|
rx_data_ready <= rx_output_strobe;
|
rx_data_ready <= rx_output_strobe;
|
end process;
|
end process;
|
|
|
|
|
-- This part translates the scan code into an ASCII value...
|
-- This part translates the scan code into an ASCII value...
|
-- Only the ASCII codes which I considered important have been included.
|
-- Only the ASCII codes which I considered important have been included.
|
-- if you want more, just add the appropriate case statement lines...
|
-- if you want more, just add the appropriate case statement lines...
|
-- (You will need to know the keyboard scan codes you wish to assign.)
|
-- (You will need to know the keyboard scan codes you wish to assign.)
|
-- The entries are listed in ascending order of ASCII value.
|
-- The entries are listed in ascending order of ASCII value.
|
shift_key_plus_code <= shift_key_on & caps_key_on & q(7 downto 1);
|
shift_key_plus_code <= shift_key_on & caps_key_on & q(7 downto 1);
|
|
|
--shift_map : process( shift_key_plus_code )
|
--shift_map : process( shift_key_plus_code )
|
--begin
|
--begin
|
-- case shift_key_plus_code is
|
-- case shift_key_plus_code is
|
-- when x"066" => ascii <= x"08"; -- Backspace ("backspace" key)
|
-- when x"066" => ascii <= x"08"; -- Backspace ("backspace" key)
|
-- when x"166" => ascii <= x"08"; -- Backspace ("backspace" key)
|
-- when x"166" => ascii <= x"08"; -- Backspace ("backspace" key)
|
-- when x"00d" => ascii <= x"09"; -- Horizontal Tab
|
-- when x"00d" => ascii <= x"09"; -- Horizontal Tab
|
-- when x"10d" => ascii <= x"09"; -- Horizontal Tab
|
-- when x"10d" => ascii <= x"09"; -- Horizontal Tab
|
-- when x"05a" => ascii <= x"0d"; -- Carriage return ("enter" key)
|
-- when x"05a" => ascii <= x"0d"; -- Carriage return ("enter" key)
|
-- when x"15a" => ascii <= x"0d"; -- Carriage return ("enter" key)
|
-- when x"15a" => ascii <= x"0d"; -- Carriage return ("enter" key)
|
-- when x"076" => ascii <= x"1b"; -- Escape ("esc" key)
|
-- when x"076" => ascii <= x"1b"; -- Escape ("esc" key)
|
-- when x"176" => ascii <= x"1b"; -- Escape ("esc" key)
|
-- when x"176" => ascii <= x"1b"; -- Escape ("esc" key)
|
-- when x"029" => ascii <= x"20"; -- Space
|
-- when x"029" => ascii <= x"20"; -- Space
|
-- when x"129" => ascii <= x"20"; -- Space
|
-- when x"129" => ascii <= x"20"; -- Space
|
-- when x"116" => ascii <= x"21"; -- !
|
-- when x"116" => ascii <= x"21"; -- !
|
-- when x"152" => ascii <= x"22"; -- "
|
-- when x"152" => ascii <= x"22"; -- "
|
-- when x"126" => ascii <= x"23"; -- #
|
-- when x"126" => ascii <= x"23"; -- #
|
-- when x"125" => ascii <= x"24"; -- $
|
-- when x"125" => ascii <= x"24"; -- $
|
-- when x"12e" => ascii <= x"25"; --
|
-- when x"12e" => ascii <= x"25"; --
|
-- when x"13d" => ascii <= x"26"; --
|
-- when x"13d" => ascii <= x"26"; --
|
-- when x"052" => ascii <= x"27"; --
|
-- when x"052" => ascii <= x"27"; --
|
-- when x"146" => ascii <= x"28"; --
|
-- when x"146" => ascii <= x"28"; --
|
-- when x"145" => ascii <= x"29"; --
|
-- when x"145" => ascii <= x"29"; --
|
-- when x"13e" => ascii <= x"2a"; -- *
|
-- when x"13e" => ascii <= x"2a"; -- *
|
-- when x"155" => ascii <= x"2b"; -- +
|
-- when x"155" => ascii <= x"2b"; -- +
|
-- when x"041" => ascii <= x"2c"; -- ,
|
-- when x"041" => ascii <= x"2c"; -- ,
|
-- when x"04e" => ascii <= x"2d"; -- -
|
-- when x"04e" => ascii <= x"2d"; -- -
|
-- when x"049" => ascii <= x"2e"; -- .
|
-- when x"049" => ascii <= x"2e"; -- .
|
-- when x"04a" => ascii <= x"2f"; -- /
|
-- when x"04a" => ascii <= x"2f"; -- /
|
-- when x"045" => ascii <= x"30"; -- 0
|
-- when x"045" => ascii <= x"30"; -- 0
|
-- when x"016" => ascii <= x"31"; -- 1
|
-- when x"016" => ascii <= x"31"; -- 1
|
-- when x"01e" => ascii <= x"32"; -- 2
|
-- when x"01e" => ascii <= x"32"; -- 2
|
-- when x"026" => ascii <= x"33"; -- 3
|
-- when x"026" => ascii <= x"33"; -- 3
|
-- when x"025" => ascii <= x"34"; -- 4
|
-- when x"025" => ascii <= x"34"; -- 4
|
-- when x"02e" => ascii <= x"35"; -- 5
|
-- when x"02e" => ascii <= x"35"; -- 5
|
-- when x"036" => ascii <= x"36"; -- 6
|
-- when x"036" => ascii <= x"36"; -- 6
|
-- when x"03d" => ascii <= x"37"; -- 7
|
-- when x"03d" => ascii <= x"37"; -- 7
|
-- when x"03e" => ascii <= x"38"; -- 8
|
-- when x"03e" => ascii <= x"38"; -- 8
|
-- when x"046" => ascii <= x"39"; -- 9
|
-- when x"046" => ascii <= x"39"; -- 9
|
-- when x"14c" => ascii <= x"3a"; -- :
|
-- when x"14c" => ascii <= x"3a"; -- :
|
-- when x"04c" => ascii <= x"3b"; -- ;
|
-- when x"04c" => ascii <= x"3b"; -- ;
|
-- when x"141" => ascii <= x"3c"; -- <
|
-- when x"141" => ascii <= x"3c"; -- <
|
-- when x"055" => ascii <= x"3d"; -- =
|
-- when x"055" => ascii <= x"3d"; -- =
|
-- when x"149" => ascii <= x"3e"; -- >
|
-- when x"149" => ascii <= x"3e"; -- >
|
-- when x"14a" => ascii <= x"3f"; -- ?
|
-- when x"14a" => ascii <= x"3f"; -- ?
|
-- when x"11e" => ascii <= x"40"; -- @
|
-- when x"11e" => ascii <= x"40"; -- @
|
-- when x"11c" => ascii <= x"41"; -- A
|
-- when x"11c" => ascii <= x"41"; -- A
|
-- when x"132" => ascii <= x"42"; -- B
|
-- when x"132" => ascii <= x"42"; -- B
|
-- when x"121" => ascii <= x"43"; -- C
|
-- when x"121" => ascii <= x"43"; -- C
|
-- when x"123" => ascii <= x"44"; -- D
|
-- when x"123" => ascii <= x"44"; -- D
|
-- when x"124" => ascii <= x"45"; -- E
|
-- when x"124" => ascii <= x"45"; -- E
|
-- when x"12b" => ascii <= x"46"; -- F
|
-- when x"12b" => ascii <= x"46"; -- F
|
-- when x"134" => ascii <= x"47"; -- G
|
-- when x"134" => ascii <= x"47"; -- G
|
-- when x"133" => ascii <= x"48"; -- H
|
-- when x"133" => ascii <= x"48"; -- H
|
-- when x"143" => ascii <= x"49"; -- I
|
-- when x"143" => ascii <= x"49"; -- I
|
-- when x"13b" => ascii <= x"4a"; -- J
|
-- when x"13b" => ascii <= x"4a"; -- J
|
-- when x"142" => ascii <= x"4b"; -- K
|
-- when x"142" => ascii <= x"4b"; -- K
|
-- when x"14b" => ascii <= x"4c"; -- L
|
-- when x"14b" => ascii <= x"4c"; -- L
|
-- when x"13a" => ascii <= x"4d"; -- M
|
-- when x"13a" => ascii <= x"4d"; -- M
|
-- when x"131" => ascii <= x"4e"; -- N
|
-- when x"131" => ascii <= x"4e"; -- N
|
-- when x"144" => ascii <= x"4f"; -- O
|
-- when x"144" => ascii <= x"4f"; -- O
|
-- when x"14d" => ascii <= x"50"; -- P
|
-- when x"14d" => ascii <= x"50"; -- P
|
-- when x"115" => ascii <= x"51"; -- Q
|
-- when x"115" => ascii <= x"51"; -- Q
|
-- when x"12d" => ascii <= x"52"; -- R
|
-- when x"12d" => ascii <= x"52"; -- R
|
-- when x"11b" => ascii <= x"53"; -- S
|
-- when x"11b" => ascii <= x"53"; -- S
|
-- when x"12c" => ascii <= x"54"; -- T
|
-- when x"12c" => ascii <= x"54"; -- T
|
-- when x"13c" => ascii <= x"55"; -- U
|
-- when x"13c" => ascii <= x"55"; -- U
|
-- when x"12a" => ascii <= x"56"; -- V
|
-- when x"12a" => ascii <= x"56"; -- V
|
-- when x"11d" => ascii <= x"57"; -- W
|
-- when x"11d" => ascii <= x"57"; -- W
|
-- when x"122" => ascii <= x"58"; -- X
|
-- when x"122" => ascii <= x"58"; -- X
|
-- when x"135" => ascii <= x"59"; -- Y
|
-- when x"135" => ascii <= x"59"; -- Y
|
-- when x"11a" => ascii <= x"5a"; -- Z
|
-- when x"11a" => ascii <= x"5a"; -- Z
|
-- when x"054" => ascii <= x"5b"; -- [
|
-- when x"054" => ascii <= x"5b"; -- [
|
-- when x"05d" => ascii <= x"5c"; -- \
|
-- when x"05d" => ascii <= x"5c"; -- \
|
-- when x"05b" => ascii <= x"5d"; -- ]
|
-- when x"05b" => ascii <= x"5d"; -- ]
|
-- when x"136" => ascii <= x"5e"; -- ^
|
-- when x"136" => ascii <= x"5e"; -- ^
|
-- when x"14e" => ascii <= x"5f"; -- _
|
-- when x"14e" => ascii <= x"5f"; -- _
|
-- when x"00e" => ascii <= x"60"; -- `
|
-- when x"00e" => ascii <= x"60"; -- `
|
-- when x"01c" => ascii <= x"61"; -- a
|
-- when x"01c" => ascii <= x"61"; -- a
|
-- when x"032" => ascii <= x"62"; -- b
|
-- when x"032" => ascii <= x"62"; -- b
|
-- when x"021" => ascii <= x"63"; -- c
|
-- when x"021" => ascii <= x"63"; -- c
|
-- when x"023" => ascii <= x"64"; -- d
|
-- when x"023" => ascii <= x"64"; -- d
|
-- when x"024" => ascii <= x"65"; -- e
|
-- when x"024" => ascii <= x"65"; -- e
|
-- when x"02b" => ascii <= x"66"; -- f
|
-- when x"02b" => ascii <= x"66"; -- f
|
-- when x"034" => ascii <= x"67"; -- g
|
-- when x"034" => ascii <= x"67"; -- g
|
-- when x"033" => ascii <= x"68"; -- h
|
-- when x"033" => ascii <= x"68"; -- h
|
-- when x"043" => ascii <= x"69"; -- i
|
-- when x"043" => ascii <= x"69"; -- i
|
-- when x"03b" => ascii <= x"6a"; -- j
|
-- when x"03b" => ascii <= x"6a"; -- j
|
-- when x"042" => ascii <= x"6b"; -- k
|
-- when x"042" => ascii <= x"6b"; -- k
|
-- when x"04b" => ascii <= x"6c"; -- l
|
-- when x"04b" => ascii <= x"6c"; -- l
|
-- when x"03a" => ascii <= x"6d"; -- m
|
-- when x"03a" => ascii <= x"6d"; -- m
|
-- when x"031" => ascii <= x"6e"; -- n
|
-- when x"031" => ascii <= x"6e"; -- n
|
-- when x"044" => ascii <= x"6f"; -- o
|
-- when x"044" => ascii <= x"6f"; -- o
|
-- when x"04d" => ascii <= x"70"; -- p
|
-- when x"04d" => ascii <= x"70"; -- p
|
-- when x"015" => ascii <= x"71"; -- q
|
-- when x"015" => ascii <= x"71"; -- q
|
-- when x"02d" => ascii <= x"72"; -- r
|
-- when x"02d" => ascii <= x"72"; -- r
|
-- when x"01b" => ascii <= x"73"; -- s
|
-- when x"01b" => ascii <= x"73"; -- s
|
-- when x"02c" => ascii <= x"74"; -- t
|
-- when x"02c" => ascii <= x"74"; -- t
|
-- when x"03c" => ascii <= x"75"; -- u
|
-- when x"03c" => ascii <= x"75"; -- u
|
-- when x"02a" => ascii <= x"76"; -- v
|
-- when x"02a" => ascii <= x"76"; -- v
|
-- when x"01d" => ascii <= x"77"; -- w
|
-- when x"01d" => ascii <= x"77"; -- w
|
-- when x"022" => ascii <= x"78"; -- x
|
-- when x"022" => ascii <= x"78"; -- x
|
-- when x"035" => ascii <= x"79"; -- y
|
-- when x"035" => ascii <= x"79"; -- y
|
-- when x"01a" => ascii <= x"7a"; -- z
|
-- when x"01a" => ascii <= x"7a"; -- z
|
-- when x"154" => ascii <= x"7b"; -- {
|
-- when x"154" => ascii <= x"7b"; -- {
|
-- when x"15d" => ascii <= x"7c"; -- |
|
-- when x"15d" => ascii <= x"7c"; -- |
|
-- when x"15b" => ascii <= x"7d"; -- }
|
-- when x"15b" => ascii <= x"7d"; -- }
|
-- when x"10e" => ascii <= x"7e"; -- ~
|
-- when x"10e" => ascii <= x"7e"; -- ~
|
-- when x"071" => ascii <= x"7f"; -- (Delete OR DEL on numeric keypad)
|
-- when x"071" => ascii <= x"7f"; -- (Delete OR DEL on numeric keypad)
|
-- when x"171" => ascii <= x"7f"; -- (Delete OR DEL on numeric keypad)
|
-- when x"171" => ascii <= x"7f"; -- (Delete OR DEL on numeric keypad)
|
-- when others => ascii <= x"ff"; -- 0xff used for unlisted characters.
|
-- when others => ascii <= x"ff"; -- 0xff used for unlisted characters.
|
-- end case;
|
-- end case;
|
--end process;
|
--end process;
|
|
|
end rtl;
|
end rtl;
|
|
|