Expected result
  ===============
  This test will blink all available on-board LEDs, one after each other in an
  endless loop. Each LED will light up once long, and twice short, where the long
  interval is roughly 4 times as long as the short interval. The length of the
  interval is not specified and differs for each platform.
  
  Background
  ==========
  Running this test shows if all the direct access macros for all on-board LEDs
  are working correctly (xx_ON, xx_OFF, xx_TOGGLE). This test is intentionally not
  using any timers, so it can also be used early on in the porting process, where
  timers might not yet be available.