SBT_1S
#define SBT_1M (SBT_1S * 60)
#define SBT_1MS (SBT_1S / 1000)
#define SBT_1US (SBT_1S / 1000000)
#define SBT_1NS (SBT_1S / 1000000000)
#define SBT2FREQ(sbt) ((SBT_1S + ((sbt) >> 1)) / (sbt))