stm32 /stm32h7rs /STM32H7R /ETH /ETH_MACPPSTTNR

Target Time Low for PPS Register This register stores the time in (signed) nanoseconds. When the value of the timestamp matches the value in both Target Timestamp registers, the MAC starts or stops the PPS signal output and generates an interrupt (if enabled) based on the TRGTMODSEL0 field (Bits [6:5]) in PPS control register (ETH_MACPPSCR). When the TSCTRLSSR bit is set in the Timestamp control Register (ETH_MACTSCR), this value should not exceed 0x3B9A_C9FF. The actual start or stop time of the PPS signal output may have an error margin up to one unit of subsecond increment value.

PPS Target Time Register Busy The MAC sets this bit when the PPSCMD0 field in the PPS control register (ETH_MACPPSCR) is programmed to 010 or 011. Programming the PPSCMD0 field to 010 or 011 instructs the MAC to synchronize the Target Time Registers to the PTP clock domain. The MAC clears this bit after synchronizing the Target Time Registers with the PTP clock domain The application must not update the Target Time Registers when this bit is read as 1. Otherwise, the synchronization of the previous programmed time gets corrupted.