NXP Semiconductors freescale K51 Series Reference Manual

S E T E X S P C C L E A R E X S P CFigure 41-19. Extended Space Operation41.7.4.2 EXSPC Operation in FSK ModeIn FSK mode, the modulator continues to count carrier out clocks, alternating betweenthe primary and secondary registers at the end of each modulation period.To calculate the length of an extended space in FSK mode, one needs to know whetherMSC[EXSPC] bit was set on a primary or secondary modulation period, as well as thetotal number of both primary and secondary modulation periods completed whileMSC[EXSPC] bit is high. A status bit for the current modulation is not accessible to theCPU. If necessary, software should maintain tracking of the current modulation cycle(primary or secondary). The extended space period ends at the completion of the spaceperiod time of the modulation period during which MSC[EXSPC] bit is cleared.If MSC[EXSPC] bit was set during a primary modulation cycle, use the equation:texspace = (tspace)p + (tmark + tspace)s + (tmark + tspace)p +...Where the subscripts p and s refer to mark and space times for the primary and secondarymodulation cycles.If MSC[EXSPC] bit was set during a secondary modulation cycle, use the equation:texspace = (tspace)s + (tmark + tspace)p + (tmark + tspace)s +...41.8 CMT Interrupts and DMAThe CMT generates an Interrupt request or a DMA transfer request according toMSC[EOCIE], MSC[EOCF], DMA[DMA] bits.Table 41-18. DMA Transfer Request x CMT Interrupt RequestMSC[EOCF] DMA[DMA] MSC[EOCIE] DMA transfer request CMT interrupt request0 X X 0 01 X 0 0 01 0 1 0 11 1 1 1 0Chapter 41 Carrier Modulator Transmitter (CMT)K51 Sub-Family Reference Manual, Rev. 6, Nov 2011Freescale Semiconductor, Inc. 1031