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AT32F435/437
Series Reference Manual
2022.11.11
Page 637
Rev 2.03
26.3.48 Ethernet PTP time stamp low register (EMAC_PTPTSL)
This register contains the lower 32 time bits. It is a read-only register containing the subsecond system
time value.
Bit
Register
Reset value
Type
Description
Bit 31
AST
0x0
ro
Add or Subtract Time
When this bit is set, the time value is subtracted from the
value of the update register. When this bit is cleared, the
time value is added to the value of the update register.
Bit 30: 0
TSS
0x0000 0000 ro
Timestamp Sub Seconds
This field indicates the subsecond system time with 0.46
ns accuracy. When the bit 9 is set in the
EMAC_PTPTSCTRL register, each bit represents 1 ns,
with the value programmed not exceeding the
0x3B9A_C9FF.
26.3.49 Ethernet PTP time stamp high update register
(EMAC_PTPTSHUD)
System time second update register and system nanosecond update register initializes or updates the
system time maintained by the MAC. It is required to write both registers before setting the TSINIT or
TSUPDT bit in the EMAC_PTPTSCTRL register.
Bit
Register
Reset value
Type
Description
Bit 31: 0
TS
0x0000 0000 rw
Timestamp Second
This field indicates the second value that is to be initialized
or added to the system time.
26.3.50 Ethernet PTP time stamp low update register
(EMAC_PTPTSLUD)
This register is present only when the IEEE1588 time stamp function is selected without an external
time stamp input.
Bit
Register
Reset value
Type
Description
Bit 31
AST
0x0
rw
Add or Subtract Time
When this bit is set, the time value is subtracted from the
value of the update register. When this bit is cleared, the
time value is added to the value of the update register.
Bit 30: 0
TSS
0x0000 0000 rw
Timestamp Sub Seconds
This field indicates the subsecond system time with 0.46
ns accuracy. When the bit 9 is set in the
EMAC_PTPTSCTRL register, each bit represents 1 ns,
with the value programmed not exceeding the
0x3B9A_C9FF.
26.3.51 Ethernet PTP time stamp addend register
(EMAC_PTPTSAD)
This register value is used only when the system time is configured for Fine update mode. This register
value is added to a 32-bit accumulator at every clock cycle (of clk_ptp_ref_i). The system time is
updated whenever the accumulator overflows.
Bit
Register
Reset value
Type
Description
Bit 31: 0
TAR
0x0000 0000 rw
Timestamp Addend Register
This field indicates the 32-bit time value to be added to the
accumulator in order to achieve time synchronization.