in reply to Perl and Can Bus

If you want to output the bytes received for 0CFFE000 and 18FEF501 onto a fixed screen position, the following could help. It's a very simplicistic approach:

open my $can_bus, "./receivetest |"
    or die "Couldn't read from CAN bus: $!";
my %last_value;
while( <$can_bus>) {
    if( /^(........:...) (........) (.*)$/ )
      
        my( $something, $id, $payload)= ($1,$2,$3);
        $last_value{ $id }= $payload;

        system('clear'); # clear screen

        # print the table
        for my $id (sort keys %last_value) {
            print "$id\t$last_value{ $id }\n";
        };

    } else {
        warn "Ignoring unknown line:";
        warn $_;
    }; 
};

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If you want something fancier than the flickering screen, you'll have to look at Curses (or NCurses).

Replies are listed 'Best First'.
Re^2: Perl and Can Bus
by Jalcock501 (Sexton) on Dec 12, 2014 at 16:25 UTC
    Hi Carion

    Thanks you have really helped

    I also need to count the amont of times an $id has been read and the elapse time between the messages, I'm not sure how to count entries in a hash, and I am trying to use the Time::Elapse module but if I doTime::Elapse->lapse($last_value{$id} = $payload); I get this output
    0C11FF00  00:00:00.002815 [00:00:00.000049 [00 00 00 00 00 00 00 00]]

but I only want

0C11FF00 00:00:00.000049 [ 00 00 00 00 00 00 00 00]

    [download]
    If I try to but the Time::Elapse anywhere else it errors or am I missing some control character to wrap around the $id
[reply]
[d/l]
[select]

      You will have to show some code that reproduces the problem.

[reply]
        Hi Carion

        Here is my code

        #!/usr/bin/perl -w

#use strict;
use Time::HiRes qw/gettimeofday/;

my $PCAN="/dev/pcan32";
my $now_milli = 1000 * gettimeofday();
my %last_value;
my $time_diff;

open my $can_bus, "receivetest -f=$PCAN | sed -e \'s/receivetest: m s 
+0x//g\' |"
    or die "Couldn't read from CAN bus: $!";

while (<$can_bus>) {
   if( /^(.......\.\d{1,3}) (........) (.*)$/ )
   {
        system('clear'); #clear screen

        my ($something,$id, $payload) = ($1,$2,$3);
        $last_value{ $id } = $payload;
    if(defined $last_value{ $id } )
    {
        $last_value{ $id }{COUNT} += 1;
        $time_diff = $now_milli - $last_value{ $id }{TIME};

        $last_value{ $id }{TIME} = $now_milli;
        $last_value{ $id }{DIFF} = $time_diff;
        $last_value{ $id }{PAYLOAD} = $payload;
    }
    else
    {
        #$last_value{ $id }{COUNT} = 1;
        $last_value{ $id }{TIME} = $now_milli;
        $last_value{ $id }{DIFF} = "NA";
        $last_value{ $id }{PAYLOAD} = $payload;
    }

        #Print Table
        for my $id (sort keys %last_value) {
            print "$id\t $last_value{ $id }\t $last_value{ $id }{COUNT
+}\t $last_value{ $id }{DIFF}\n";
            }
    }
    #else {
   #     warn "ignore unknown line: ";
   #     warn $_;
   # }
}

        [download]

        Unfortunately I cannot get the time between messages to calculate properly, I need how many milliseconds since the last $id was defined.

        any ideas?
[reply]
[d/l]

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