-- -----------------------------------------------------------------------------
-- TXD2IRDA - a RS232 TxD signal to IrDA 1.0 signal generator --
-- -----------------------------------------------------------------------------
--
-- File : 'txd2irda.vhd'
-- Author : Lars Larsson
--
-- Date : February 15, 1999
--
-- Description : This converts a RS232 TxD signal into an IrDA 1.0 TxD signal
-- with 3/16 duty cycle. The baud rate is adjusted by the bit
-- time parameter T.
--
-- -----------------------------------------------------------------------------
--
-- Copyright (C) 1999 Lars Larsson, Dept. of Computer Science
-- University of Hamburg
-- Vogt-Koelln-Str. 30
-- D - 22041 Hamburg, Germany
-- larsson@informatik.uni-hamburg.de
-- http://tech-www.informatik.uni-hamburg.de/~larsson
--
-- 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 the
-- Free Software Foundation; either version 2 of the License, or (at your
-- option) any later version.
--
-- This program is distributed in the hope that it will be useful, but
-- WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
-- for more details.
--
-- You should have received a copy of the GNU General Public License along
-- with this program; if not, write to the Free Software Foundation, Inc.,
-- 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
--
-- -----------------------------------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
entity txd2irda is
port(
t : in time; -- T_BAUD = 1/(baud rate)
rs232_txd : in std_ulogic; -- RS232 TxD signal input
irda_txd : out std_ulogic -- IrDA 1.0 TXD output (high active)
);
end txd2irda;
architecture simulate of txd2irda is
signal irda_s : std_ulogic;
begin
irda_p : process
begin
wait on rs232_txd for 1 ns; wait for 7*t/16;
irda_s <= '1'; wait for 3*t/16;
irda_s <= '0'; wait for 6*t/16;
end process;
irda_txd <= irda_s and (not rs232_txd);
end simulate;
-- -----------------------------------------------------------------------------
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