Hi all, I'm new with 1-wire & owfs, and I'm having a little problem.
I'm doing a little "access control" based on iButton (DS1990A). It is read
with an usb key (DS9490R). The usb is accessed via owserver, and my perl
script uses OWNet.pm library.
While scripting I encountered this error:
Use of uninitialized value $r[1] in numeric eq (==) at
/usr/local/share/perl/5.10.1/OWNet.pm line 630.
substr outside of string at /usr/local/share/perl/5.10.1/OWNet.pm line 632.
After such error, my script goes wrong, getting inconsistent data from
owserver. I noticed that in reply of a $owserver->dir("/") loop, data are
returned 1 at time instead of all-together, or the iButton result present
randomly for a long time after I detached it...
After a lot of test I can replicate the error short circuiting the iButton
probe. I encountered it the first time while testing the script: sometimes
attaching/detaching rapidly the iButton can do it, because while it is non
perfectly inserted the border... :( As a confirm, I also found (later...
:( ) this log from owserver:
CALL: ow_dir.c:(98) path=/
DATA: ow_usb_msg.c:(183) Status byte[0]: A
DATA: ow_usb_msg.c:(186) short detected
CONNECT: ow_reset.c:(36) 1-wire bus short circuit.
DATA: ow_ds9490.c:(687) CRC error
I also tried to solve it inserting a little resistance in series of the
probe, but the error is still there.
May be the resistance too little? Mmm, I don't think it: I tested different
resistance: if it is big, I don't see the iButton, else I got the error...
On the other hand, is correct: is part of the "resistance" of the protocol
recognize this type of problems.
Only I did not expect to find traces, in another way, in my script: (
I'd like to know if the lib error is a "correct" behavior (or
uncorrectable).
I'm working on Ubuntu 11.04 - Perl 5.10 and owfs 2.8p14
A simplified script I used to replicate my error is this:
#!/usr/bin/perl
use strict;
#use warnings;
use FileHandle;
use POSIX;
use Time::HiRes qw(usleep);
use OWNet ;
use constant DEBUG => 1;
my $owserver = OWNet->new( "localhost:4304" ) ;
# Workaround for buffer problem
my $new_stdout = FileHandle->new_from_fd(dup(fileno(STDOUT)), 'w');
$new_stdout->autoflush(1);
my @key_found;
sub scan_bus {
my $dir_list = $owserver->dir('/');
if ( defined($dir_list) ) {
@key_found = split /,/ , $dir_list;
}
print { $new_stdout } "\ndir_list @key_found\n" if DEBUG; }
while ( 1 ) {
&scan_bus;
usleep(100000);
print { $new_stdout } ".\n" if DEBUG;
}
-----------------------
For completeness, I use this /etc/owfs.conf file:
usb
link=127.0.0.1:4304
Celsius
pid_file = /var/run/owserver.pid
uncached
foreground
error_print 2
error_level 4
# Timeouts (all in seconds)
# cache for values that change on their own timeout_volatile = 1 # seconds
"volatile" values remain in cache # cache for values that change on command
timeout_stable = 4 # seconds "stable" values remain in cache # cache for
directory lists (non-alarm) timeout_directory = 1 # seconds "directory"
values remain in cache # cache for 1-wire device location timeout_presence
= 4 # seconds "device presence" (which bus)
timeout_ha7 = 1
timeout_w1 = 1
Thanks
Giulio Carabetta
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