sleepenh 1.7-1 (ppc64el binary) in ubuntu disco

 sleepenh is a sleep program for shell scripts that need to
 perform a loop that repeats at a regular time interval, without
 cumulative errors.
 .
 It supports microsecond resolution.
 .
 You can also specify the time you need between two calls
 of sleepenh.
 .
 Here follows an usage example to clarify its purpose. This
 example sends 'A' to ttyS0 every 1.2 seconds.
   #!/bin/sh
   # does not wait (or wait 0), just to get initial timestamp
   TIMESTAMP=$(sleepenh 0)
   while true; do
     # send the byte to ttyS0
     echo -n "A" > /dev/ttyS0;
     # wait until the required time
     TIMESTAMP=$(sleepenh $TIMESTAMP 1.200);
   done
 .
 For more details, please read the manpage.