SYNOPSIS

       modprobe pcfclock [parport=number,...]

DESCRIPTION

       The  pcfclock devices are character devices for the parallel port radio
       clock sold by Conrad Electronic under order number 967602.

       The radio clock, which is put between a parallel port and your printer,
       receives the legal German time, i.e. CET or CEST, from the DCF77 trans-
       mitter and uses it to set its internal quartz clock.

       If the Linux Device Filesystem is mounted the device files  are  avail-
       able in the pcfclocks subdirectory. The old-style device files are typ-
       ically created by:

              mknod -m 444 /dev/pcfclock0 c 181 0
              mknod -m 444 /dev/pcfclock1 c 181 1
              mknod -m 444 /dev/pcfclock2 c 181 2

       The time information requested from the radio  clock  is  put  into  an
       array  of  18  bytes  by the device driver.  The following Perl program
       shows how to decode the information stored in the array:

              sysopen(FH, "/dev/pcfclock0", 0) or die "$!";
              sysread(FH, $buf, 18);
              close(FH);
              @time = unpack("C18", $buf);
              die "invalid time data" if $time[0] != 9;
              $not_in_sync = ($time[1] & 1);
              $sec  = $time[2] + 10 * $time[3];
              $min  = $time[4] + 10 * $time[5];
              $hour = $time[6] + 10 * $time[7];
              if (($time[8] & 3) == 1) {
                  $isdst = 1;
              } elsif (($time[8] & 3) == 2) {
                  $isdst = 0;
              } else {
                  $isdst = -1;
              }
              $battery_low = ($time[8] & 4);
              $wday = $time[9];
              $mday = $time[10] + 10 * $time[11];
              $mon  = $time[12] + 10 * $time[13];
              $year = $time[14] + 10 * $time[15];
              $usec = 31250 * $time[16];
              $usec += 500000 if ($time[17] & 1);

       $wday ranges from 1 to 7, i.e. from Monday to Sunday.  $mon ranges from
       1 to 12 and $year from 0 to 99.

OPTIONS

       If  the  driver is loaded as a module you can configure it using module
       /dev/pcfclock*

DIAGNOSTICS

       The following kernel messages can be printed.

       pcfclock: no devices found
              No parallel port exists or there is no working radio clock  con-
              nected to any parallel port.

       pcfclock: no radio clock found at parport0
              Either there is no radio clock at the given parallel port or the
              clock has not received the time from the DCF77 transmitter  yet.

       pcfclock: not in sync at parport0
              The  last radio reception failed, i.e. the radio clock is not in
              sync with the DCF77 transmitter.

       pcfclock: battery status low at parport0
              The radio clock's battery must be replaced.

AUTHOR

       Andreas Voegele

SEE ALSO

       mknod(1), modprobe(8), pcfdate(8).



                               December 22, 2003                   PCFCLOCK(4)