Configures and starts four different pulse trains on GPIO LEDs.

  - P3.0 LED0 - PT8 setup as 1Hz continuous signal that outputs 10110b
  - P3.1 LED1 - PT9 setup as 10Hz continuous square wave
  - P3.2 LED2 - PT10 setup to loop twice and then start PT11
  - P3.3 LED3 - PT11 setup to loop twice and then start PT10
  - P5.4 SW1 - push button setup to stop/start pulse trains

Note:
  Interrupts for pulse trains are enabled but the interrupt handler only
  clears the flags and prints them to stdout (terminal at 115200 bps).