gmacgrp_sub_second_increment
In the Coarse Update mode (TSCFUPDT bit in Register 448), the value in this register is added to the system time every clock cycle of clk_ptp_ref_i. In the Fine Update mode, the value in this register is added to the system time whenever the Accumulator gets an overflow.
Module Instance | Base Address | Register Address |
---|---|---|
i_emac_emac0 | 0xFF800000 | 0xFF800704 |
i_emac_emac1 | 0xFF802000 | 0xFF802704 |
i_emac_emac2 | 0xFF804000 | 0xFF804704 |
Size: 32
Offset: 0x704
Access: RW
Important: The value of a reserved bit must be maintained in software. When you modify registers containing reserved bit fields, you must use a read-modify-write operation to preserve state and prevent indeterminate system behavior.
Bit Fields | |||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 |
Reserved |
|||||||||||||||
15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
Reserved |
ssinc RW 0x0 |
gmacgrp_sub_second_increment Fields
Bit | Name | Description | Access | Reset |
---|---|---|---|---|
7:0 | ssinc |
The value programmed in this field is accumulated every clock cycle (of clk_ptp_i) with the contents of the sub-second register. For example, when PTP clock is 50 MHz (period is 20 ns), you should program 20 (0x14) when the System Time-Nanoseconds register has an accuracy of 1 ns (TSCTRLSSR bit is set). When TSCTRLSSR is clear, the Nanoseconds register has a resolution of ~0.465ns. In this case, you should program a value of 43 (0x2B) that is derived by 20ns/0.465. |
RW | 0x0 |