pub type USICS_W<'a, REG> = FieldWriter<'a, REG, 2, USICS_A, Safe>;
Field USICS writer - USI Clock Source Select Bits
USICS
struct USICS_W<'a, REG> { /* private fields */ }
No Clock/Software clock strobe
Timer/Counter0 Compare Match
External, positive edge
External, negative edge