# xtimer_drift test application
  
  Make note of the PC clock when starting this test. Let it run for a while, and
  compare the printed time against the expected time from the PC clock. The
  difference is the RIOT timer drift, this is likely caused by either:
  
  - an inaccurate hardware timer, or
  - bugs in the software (xtimer or periph/timer)
  
  This test will run a periodic timer every `TEST_INTERVAL` microseconds (`TEST_HZ`).
  The current time will be printed once per second, along with the difference
  between the actual and expected `xtimer_now` value. The first output variable
  `drift`, represents the total offset since start between `xtimer_now` and the
  expected time. The second output variable `jitter`, represents the difference
  in drift from the last printout. Two other threads are also running only to
  cause CPU load with extra interrupts and context switches.