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/o8_epoch_timer.vhd
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-- Copyright (c)2011, 2019, 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_epoch_timer |
-- Description: Provides a 24-bit, 4uS resolution elapsed timer with |
-- : alarm and interrupt for the Open8 CPU. |
-- |
-- Notes : Requires an externally provided uSec tick input - one clock |
-- : per microsecond. |
-- |
-- Register Map: |
-- Offset Bitfield Description Read/Write |
-- 0x0 AAAAAAAA B0 of Setpoint (W) or Buffered Time(R) |
-- 0x1 AAAAAAAA B1 of Setpoint (W) or Buffered Time(R) |
-- 0x2 AAAAAAAA B2 of Setpoint (W) or Buffered Time(R) |
-- 0x3 C-----BA Control/Status register (RW) |
-- A = Update Buffered Time from internal timer (W) |
-- B = Reset Internal Epoch Time (W) |
-- C = Alarm State Flag (RW) (write a 1 to clear) |
-- |
-- Revision History |
-- Author Date Change |
------------------ -------- --------------------------------------------------- |
-- Seth Henry 07/28/11 Design Start |
-- Seth Henry 12/19/19 Renamed to "o8_epoch_timer" to fit "theme" |
-- Copyright (c)2011, 2019, 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_epoch_timer |
-- Description: Provides a 24-bit, 4uS resolution elapsed timer with |
-- : alarm and interrupt for the Open8 CPU. |
-- |
-- Notes : Requires an externally provided uSec tick input - one clock |
-- : per microsecond. |
-- |
-- Register Map: |
-- Offset Bitfield Description Read/Write |
-- 0x0 AAAAAAAA B0 of Buffered Setpoint (W) or Current Setpoint(R) |
-- 0x1 AAAAAAAA B1 of Buffered Setpoint (W) or Current Setpoint(R) |
-- 0x2 AAAAAAAA B2 of Buffered Setpoint (W) or Current Setpoint(R) |
-- 0x3 BA------ Status of buffer/alarm (1 = pending, 0 = current) |
-- A = Pending status (R) |
-- B = Alarm status (R) |
-- Note that any write will update the internal set point |
-- and clear the alarm |
-- 0x4 AAAAAAAA B0 of Current Epoch Time(RO) |
-- 0x5 AAAAAAAA B1 of Current Epoch Time(RO) |
-- 0x6 AAAAAAAA B2 of Current Epoch Time(RO) |
-- Note that any write to 0x04,0x05, or 0x06 will copy the |
-- current epoch time to a readable output buffer |
-- 0x7 -------- Epoch Time Latch/Clear Control Register |
-- Any write to 0x7 will clear/reset the timer and compare val |
-- |
-- Revision History |
-- Author Date Change |
------------------ -------- --------------------------------------------------- |
-- Seth Henry 07/28/11 Design Start |
-- Seth Henry 12/19/19 Renamed to "o8_epoch_timer" to fit "theme" |
|
library ieee; |
use ieee.std_logic_1164.all; |
use ieee.std_logic_unsigned.all; |
use ieee.std_logic_arith.all; |
use ieee.std_logic_misc.all; |
|
library work; |
use work.open8_pkg.all; |
|
entity o8_epoch_timer is |
generic( |
Reset_Level : std_logic; |
Address : ADDRESS_TYPE |
); |
port( |
Clock : in std_logic; |
Reset : in std_logic; |
uSec_Tick : in std_logic; |
-- |
Bus_Address : in ADDRESS_TYPE; |
Wr_Enable : in std_logic; |
Wr_Data : in DATA_TYPE; |
Rd_Enable : in std_logic; |
Rd_Data : out DATA_TYPE; |
Interrupt : out std_logic |
); |
end entity; |
|
architecture behave of o8_epoch_timer is |
|
constant User_Addr : std_logic_vector(15 downto 3) |
:= Address(15 downto 3); |
alias Comp_Addr is Bus_Address(15 downto 3); |
signal Addr_Match : std_logic := '0'; |
|
alias Reg_Addr is Bus_Address(2 downto 0); |
signal Reg_Addr_q : std_logic_vector(2 downto 0) := (others => '0'); |
|
signal Wr_En : std_logic := '0'; |
signal Wr_Data_q : DATA_TYPE := x"00"; |
signal Rd_En : std_logic := '0'; |
|
library ieee; |
use ieee.std_logic_1164.all; |
use ieee.std_logic_unsigned.all; |
use ieee.std_logic_arith.all; |
use ieee.std_logic_misc.all; |
signal setpt_buffer : std_logic_vector(23 downto 0) := (others => '0'); |
alias setpt_buffer_b0 is setpt_buffer(7 downto 0); |
alias setpt_buffer_b1 is setpt_buffer(15 downto 8); |
alias setpt_buffer_b2 is setpt_buffer(23 downto 16); |
|
signal epoch_buffer : std_logic_vector(23 downto 0) := (others => '0'); |
alias epoch_buffer_b0 is epoch_buffer(7 downto 0); |
alias epoch_buffer_b1 is epoch_buffer(15 downto 8); |
alias epoch_buffer_b2 is epoch_buffer(23 downto 16); |
signal buffer_pending : std_logic := '0'; |
signal buffer_update : std_logic := '0'; |
signal timer_clear : std_logic := '0'; |
|
signal epoch_tmr : std_logic_vector(25 downto 0) := (others => '0'); |
alias epoch_tmrcmp is epoch_tmr(25 downto 2); |
signal epoch_setpt : std_logic_vector(25 downto 0) := (others => '0'); |
alias epoch_setpt_b0 is epoch_setpt(7 downto 0); |
alias epoch_setpt_b1 is epoch_setpt(15 downto 8); |
alias epoch_setpt_b2 is epoch_setpt(23 downto 16); |
alias epoch_setpt_u is epoch_setpt(25 downto 2); |
alias epoch_setpt_l is epoch_setpt(1 downto 0); |
signal epoch_alarm : std_logic := '0'; |
signal epoch_alarm_q : std_logic := '0'; |
|
begin |
|
Addr_Match <= '1' when Comp_Addr = User_Addr else '0'; |
|
io_reg: process( Clock, Reset ) |
begin |
if( Reset = Reset_Level )then |
Wr_Data_q <= (others => '0'); |
Reg_Addr_q <= (others => '0'); |
Wr_En <= '0'; |
Rd_En <= '0'; |
Rd_Data <= OPEN8_NULLBUS; |
setpt_buffer <= (others => '0'); |
epoch_buffer <= (others => '0'); |
buffer_pending <= '0'; |
buffer_update <= '0'; |
timer_clear <= '0'; |
elsif( rising_edge( Clock ) )then |
|
Reg_Addr_q <= Reg_Addr; |
Wr_En <= Addr_Match and Wr_Enable; |
Wr_Data_q <= Wr_Data; |
|
buffer_update <= '0'; |
timer_clear <= '0'; |
if( Wr_En = '1' )then |
case( Reg_Addr_q )is |
when "000" => |
setpt_buffer_b0 <= Wr_Data_q; |
buffer_pending <= '1'; |
|
when "001" => |
setpt_buffer_b1 <= Wr_Data_q; |
buffer_pending <= '1'; |
|
when "010" => |
setpt_buffer_b2 <= Wr_Data_q; |
buffer_pending <= '1'; |
|
library work; |
use work.open8_pkg.all; |
when "011" => |
buffer_update <= '1'; |
buffer_pending <= '0'; |
|
entity o8_epoch_timer is |
generic( |
Reset_Level : std_logic; |
Address : ADDRESS_TYPE |
); |
port( |
Clock : in std_logic; |
Reset : in std_logic; |
uSec_Tick : in std_logic; |
-- |
Bus_Address : in ADDRESS_TYPE; |
Wr_Enable : in std_logic; |
Wr_Data : in DATA_TYPE; |
Rd_Enable : in std_logic; |
Rd_Data : out DATA_TYPE; |
Interrupt : out std_logic |
); |
end entity; |
|
architecture behave of o8_epoch_timer is |
|
constant User_Addr : std_logic_vector(15 downto 2) |
:= Address(15 downto 2); |
alias Comp_Addr is Bus_Address(15 downto 2); |
signal Addr_Match : std_logic; |
|
alias Reg_Addr is Bus_Address(1 downto 0); |
signal Reg_Addr_q : std_logic_vector(1 downto 0); |
|
signal Wr_En : std_logic; |
signal Wr_Data_q : DATA_TYPE; |
signal Rd_En : std_logic; |
|
signal epoch_tmr : std_logic_vector(25 downto 0); |
alias epoch_tmrcmp is epoch_tmr(25 downto 2); |
signal epoch_buffer : std_logic_vector(23 downto 0); |
signal epoch_setpt : std_logic_vector(25 downto 0); |
signal epoch_alarm : std_logic; |
signal epoch_alarm_q : std_logic; |
|
begin |
|
Addr_Match <= '1' when Comp_Addr = User_Addr else '0'; |
|
io_reg: process( Clock, Reset ) |
begin |
if( Reset = Reset_Level )then |
epoch_tmr <= (others => '0'); |
epoch_buffer <= (others => '0'); |
epoch_setpt <= (others => '0'); |
epoch_alarm <= '0'; |
epoch_alarm_q <= '0'; |
Wr_Data_q <= (others => '0'); |
Reg_Addr_q <= (others => '0'); |
Wr_En <= '0'; |
Rd_En <= '0'; |
Rd_Data <= OPEN8_NULLBUS; |
Interrupt <= '0'; |
elsif( rising_edge( Clock ) )then |
epoch_tmr <= epoch_tmr + uSec_Tick; |
-- Force the lower bits of the setpoint to "11" so that the offset is |
-- reduced to 1uS (reproducing the original behavior). Software should |
-- always subtract 4uS (-1) from the desired time to compensate |
epoch_setpt(1 downto 0) <= "11"; |
if( epoch_setpt(25 downto 2) = 0 )then |
epoch_setpt(1 downto 0) <= "00"; |
when "100" | "101" | "110" => |
epoch_buffer <= epoch_tmrcmp; |
|
when "111" => |
timer_clear <= '1'; |
when others => null; |
end case; |
end if; |
|
Rd_Data <= OPEN8_NULLBUS; |
Rd_En <= Addr_Match and Rd_Enable; |
if( Rd_En = '1' )then |
case( Reg_Addr_q )is |
when "000" => |
Rd_Data <= epoch_setpt_b0; |
when "001" => |
Rd_Data <= epoch_setpt_b1; |
when "010" => |
Rd_Data <= epoch_setpt_b2; |
when "011" => |
Rd_Data <= epoch_alarm & buffer_pending & "000000"; |
when "100" => |
Rd_Data <= epoch_buffer_b0(7 downto 0); |
when "101" => |
Rd_Data <= epoch_buffer_b1(15 downto 8); |
when "110" => |
Rd_Data <= epoch_buffer_b2(23 downto 16); |
when others => null; |
end case; |
end if; |
end if; |
end process; |
|
timer_proc: process( Clock, Reset ) |
begin |
if( Reset = Reset_Level )then |
epoch_setpt <= (others => '0'); |
epoch_tmr <= (others => '0'); |
epoch_alarm <= '0'; |
epoch_alarm_q <= '0'; |
Interrupt <= '0'; |
|
elsif( rising_edge(Clock) )then |
|
epoch_tmr <= epoch_tmr + uSec_Tick; |
|
-- Set and hold on alarm condition |
if( epoch_tmr > epoch_setpt and epoch_setpt > 0 )then |
epoch_alarm <= '1'; |
end if; |
|
if( buffer_update = '1' )then |
epoch_setpt_u <= setpt_buffer; |
-- Force the lower bits of the setpoint to "11" so that the offset is |
-- reduced to 1uS (reproducing the original behavior). Software should |
-- always subtract 4uS (-1) from the desired time to compensate |
epoch_setpt_l <= (others => or_reduce(setpt_buffer)); |
epoch_alarm <= '0'; |
end if; |
|
if( timer_clear = '1' )then |
epoch_setpt <= (others => '0'); |
epoch_tmr <= (others => '0'); |
epoch_alarm <= '0'; |
end if; |
|
Reg_Addr_q <= Reg_Addr; |
Wr_Data_q <= Wr_Data; |
|
Wr_En <= Addr_Match and Wr_Enable; |
if( Wr_En = '1' and or_reduce(Reg_Addr_q) = '0' )then |
epoch_buffer <= epoch_tmrcmp(25 downto 2); |
end if; |
|
if( Wr_En = '1' )then |
case( Reg_Addr_q )is |
when "00" => |
epoch_setpt(9 downto 2) <= Wr_Data_q; |
when "01" => |
epoch_setpt(17 downto 10) <= Wr_Data_q; |
when "10" => |
epoch_setpt(25 downto 18) <= Wr_Data_q; |
when "11" => |
if( Wr_Data_q(0) = '1' )then |
epoch_buffer <= epoch_tmrcmp; |
end if; |
if( Wr_Data_q(1) = '1' )then |
epoch_tmr <= (others => '0'); |
end if; |
if( Wr_Data_q(7) = '1' )then |
epoch_alarm <= '0'; |
end if; |
|
when others => null; |
end case; |
end if; |
|
-- Set and hold on alarm condition |
if( epoch_tmr > epoch_setpt and epoch_setpt > 0 )then |
epoch_alarm <= '1'; |
end if; |
|
epoch_alarm_q <= epoch_alarm; |
-- Fire on rising edge of epoch_alarm |
Interrupt <= epoch_alarm and not epoch_alarm_q; |
|
Rd_Data <= OPEN8_NULLBUS; |
Rd_En <= Addr_Match and Rd_Enable; |
if( Rd_En = '1' )then |
case( Reg_Addr_q )is |
when "00" => |
Rd_Data <= epoch_buffer(7 downto 0); |
when "01" => |
Rd_Data <= epoch_buffer(15 downto 8); |
when "10" => |
Rd_Data <= epoch_buffer(23 downto 16); |
when "11" => |
Rd_Data <= epoch_alarm & "0000000"; |
when others => null; |
end case; |
end if; |
end if; |
end process; |
|
end architecture; |
|
epoch_alarm_q <= epoch_alarm; |
-- Fire on rising edge of epoch_alarm |
Interrupt <= epoch_alarm and not epoch_alarm_q; |
|
end if; |
end process; |
|
end architecture; |