12.2.1.4.6.8.3 Enhanced Scheduled Traffic Time Interval
Each Ethernet port has an Enhanced Scheduled Traffic Function (ESTF) generator in the CPTS submodule.
The EST function generator generates the EST time interval as a configured number of CPTS reference clocks (CPTS_RFT_CLK).
The EST function generator rising edge is the cycle start time and the cycle repeats (cycle start occurs) after every time interval.
The first fetch allowed value is at the port base address zero in the EST fetch RAM and is actually applied 16 wireside clocks after cycle start. The 16 clock cycle delay allows the first fetch value time to be fetched from the EST fetch RAM (prefetch time at cycle start).
Each successive fetch allow is applied for the
associated fetch count thereafter. The minimum
non-zero fetch count is 16. The minimum value of
16 guarantees that the next fetch value has time
to be fetched before the current fetch count is
over. There are 64 maximum fetch values when
CPSW3_CPSW_NU_CPSW_NU_ETH_MAC_i_PN_EST_CONTROL_REG[0]
EST_ONEBUF = 0h, and 128 maximum fetch values when
CPSW3_CPSW_NU_CPSW_NU_ETH_MAC_i_PN_EST_CONTROL_REG[0]
EST_ONEBUF = 1h.
The next cycle start then causes the fetch to once again start at the port address zero.