#!/usr/bin/perl -w
#
# vfdclock
# John Simpson <jms1@jms1.net> 2006-03-19
#
# simple clock for IEE two-line VFD display
# http://www.ieeinc.com/specs/S036x2.pdf
#
# meant to run continuously, under daemontools or similar.
# daemontools run script will look like this:
#
# 	#!/bin/sh
# 	exec ./vfdclock 2>&1
#
# 2007-10-29 jms1 - added comments and copyright notice, suitable for 
#  public release on http://www.jms1.net/code/#vfdclock
#
###############################################################################
#
# Copyright (C) 2006-2007 John Simpson.
#
# 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 or version 3 of the
# license, at your option.
#
# 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, see <http://www.gnu.org/licenses/>.
#
###############################################################################

require 5.003 ;
use strict ;

use Time::HiRes qw ( usleep ) ;

my $dev = "/dev/ttyS1" ;

my @dow = qw ( u m t w r f a ) ;

$| = 1 ;

###############################################################################
#
# convert a hex string into bytes (i.e. "48656C6c6f" => "Hello")

sub hstr($)
{
	my $hs = $_[0] ;
	my $rv = "" ;
	while ( $hs =~ s/^(..)// )
	{
		$rv .= chr(hex($1)) ;
	}
	return $rv ;
}

###############################################################################
###############################################################################
###############################################################################
#
# someone set up us the serial port
# open and initialize the display

system "stty 9600 cs8 -parenb -cstopb < $dev" ;

open ( D , ">$dev" ) or die "Can\'t open $dev: $!\n" ;

my $oh = select ( D ) ;
$| = 1 ;
select ( $oh ) ;

########################################
# reset, cursor off
# http://www.ieeinc.com/specs/S036x2.pdf pages 26-37

#my $init = hstr ( "140E" ) ;	# reset, cursor off- ugly blinky display
my $init = hstr ( "0E1613" ) ;	# cursor off, home, bottom row h-scroll

###############################################################################
#
# im in ur display, showin u teh time

my $lt = 0 ;

while ( 1 )
{
	my $now = time() ;		# resolution one second
	next if ( $lt == $now ) ;

	my @l = localtime $now ;
	my @g = gmtime $now ;

	printf D "%s%s %s%02d-%02d %02d:%02d:%02d" , $init ,
		( $l[8] ? "EDT" : "EST" ) ,
		$dow[$l[6]] , $l[4]+1 , $l[3] ,
		$l[2] , $l[1] , $l[0] ;

	printf D "\r\nGMT %s%02d-%02d %02d:%02d:%02d" ,
		$dow[$g[6]] , $g[4]+1 , $g[3] ,
		$g[2] , $g[1] , $g[0] ;

	$lt = $now ;
	usleep ( 950_000 ) ;	# sleep "most of" one second
}

close D ;