Ieee 802.3Az Energy Efficient Ethernet - Altera cyclone V Technical Reference

cv_5v4
2016.10.28
Reference Timing Source
The EMAC supports the following reference timing source features defined in the IEEE 1588-2008
standard:
• 48-bit seconds field
• Fixed pulse-per-second output
• Flexible pulse-per-second output
• Auxiliary snapshots (timestamps) with external events
Transmit Path Functions
The advanced timestamp feature is supported through the descriptors format.
Receive Path Functions
The MAC processes the received frames to identify valid PTP frames. You can control the snapshot of the
time to be sent to the application, by using the following options:
• Enable timestamp for all frames.
• Enable timestamp for IEEE 1588 version 2 or version 1 timestamp.
• Enable timestamp for PTP frames transmitted directly over Ethernet or UDP/IP Ethernet.
• Enable timestamp snapshot for the received frame for IPv4 or IPv6.
• Enable timestamp snapshot for EVENT messages (SYNC, DELAY_REQ, PDELAY_REQ, or
PDELAY_RESP) only.
• Enable the node to be a master or slave and select the timestamp type to control the type of messages
for which timestamps are taken.
The DMA returns the timestamp to the software inside the corresponding transmit or receive descriptor.
Auxiliary Snapshot
The auxiliary snapshot feature allows you to store a snapshot (timestamp) of the system time based on an
external event. The event is considered to be the rising edge of the sideband signal
from the FPGA. One auxiliary snapshot input is available. The depth of the auxiliary snapshot FIFO buffer
is 16.
The timestamps taken for any input are stored in a common FIFO buffer. The host can read Register 458
(Timestamp Status Register) to know which input's timestamp is available for reading at the top of this
FIFO buffer.
Only 64-bits of the timestamp are stored in the FIFO. You can read the upper 16-bits of seconds from
Register 457 (System Time - Higher Word Seconds Register) when it is present. When a snapshot is stored,
the MAC indicates this to the host with an interrupt. The value of the snapshot is read through a FIFO
register access. If the FIFO becomes full and an external trigger to take the snapshot is asserted, then a
snapshot trigger-missed status (
that the latest auxiliary snapshot of the timestamp was not stored in the FIFO. The latest snapshot is not
written to the FIFO when it is full. When a host reads the 64-bit timestamp from the FIFO, the space
becomes available to store the next snapshot. You can clear a FIFO by setting Bit 19 (
448 (Timestamp Control Register). When multiple snapshots are present in the FIFO, the count is
indicated in Bits [27:25],

IEEE 802.3az Energy Efficient Ethernet

Energy Efficient Ethernet (EEE) standardized by IEEE 802.3-az, version D2.0 is supported by the EMAC.
It is supported by the MAC operating in 10/100/1000 Mbps rates. EEE is only supported when the EMAC
Ethernet Media Access Controller
Send Feedback
†
†
†
†
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) is set in Register 458 (Timestamp Status Register). This indicates
ATSSTM
, of Register 458 (Timestamp Status Register).
ATSNS
Reference Timing Source
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ptp_aux_ts_trig_i
ATSFC
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17-55
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) in Register
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