Datasheet

1205
SAM4E [DATASHEET]
Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14
at both ends of a link send both types of frames (regardless of whether they contain a master or slave clock). The
Pdelay_Resp message contains the time at which a Pdelay_Req was received and is itself an event message. The
time at which a Pdelay_Resp message is received is returned in a Pdelay_Resp_Follow_Up message.
1588 version 2 introduces transparent clocks of which there are two kinds, peer-to-peer (P2P) and end-to-end
(E2E). Transparent clocks measure the transit time of event messages through a bridge and amend a correction
field within the message to allow for the transit time. P2P transparent clocks additionally correct for the delay in the
receive path of the link using the information gathered from the peer delay frames. With P2P transparent clocks
delay_req messages are not used to measure link delay. This simplifies the protocol and makes larger systems
more stable.
The GMAC recognizes four different encapsulations for PTP event messages:
1. 1588 version 1 (UDP/IPv4 multicast)
2. 1588 version 2 (UDP/IPv4 multicast)
3. 1588 version 2 (UDP/IPv6 multicast)
4. 1588 version 2 (Ethernet multicast)
Table 43-5. Example of Sync Frame in 1588 Version 1 Format
Frame Segment Value
Preamble/SFD 55555555555555D5
DA (Octets 0–5) —
SA (Octets 6–11) —
Type (Octets 12–13) 0800
IP stuff (Octets 14–22) —
UDP (Octet 23) 11
IP stuff (Octets 24–29) —
IP DA (Octets 30–32) E00001
IP DA (Octet 33) 81 or 82 or 83 or 84
source IP port (Octets 34–35) —
dest IP port (Octets 36–37) 013F
other stuff (Octets 38–42) —
version PTP (Octet 43) 01
other stuff (Octets 44–73) —
control (Octet 74) 00
other stuff (Octets 75–168) —
Table 43-6. Example of Delay Request Frame in 1588 Version 1 Format
Frame Segment Value
Preamble/SFD 55555555555555D5
DA (Octets 0–5) —
SA (Octets 6–11) —
Type (Octets 12–13) 0800
IP stuff (Octets 14–22) —