In Asynchronous mode (MODE = 'b000), steering takes effect
at the end of the instruction cycle that writes to STRx. In Asynchronous Steering mode,
the output signal may be an incomplete waveform (see figure below). This operation may
be useful when the user firmware needs to immediately remove a signal from the output
pin.
Figure 1. Example of Asynchronous Steering
(MODE = 
'b000)