Implementing an IEEE 1588 V2 Node on the ColdFire MCF5441x ...

<strong>IEEE</strong> <strong>1588</strong> basic overview
4
t3 = timestamp
of delay_req msg received
t3
delay_requ msg
delay_resp msg
(includes t3)
Figure 2. offset <strong>an</strong>d delay measurement—delay messages
Figure 3 serves as <strong>an</strong> example of the <strong>IEEE</strong> <strong>1588</strong> synchronization sequence (one cycle) <strong>an</strong>d calculation of
the actual offset <strong>an</strong>d the actual delay between master <strong>an</strong>d slave node.
100
102
104
106
108
110
112
Estimated
Send Time
(100)
Precise
Send
Time
(101)
B
Precise
Receive
Time
(108)
Master Clock
PTP Appl. G/MII
t 0
t 3
Key Equations:
A = t1 –t0 = Delay + Offset
B = t3 -t2 = Delay – Offset
Delay = (A+B) / 2
Offset = (A-B) / 2
System A
(Master)
SYNC(100??)
FOLLOW_UP(101!)
DELAY_REQ
DELAY_RESP(108)
System B
(Slave)
Figure 3. <strong>IEEE</strong> <strong>1588</strong> synchronization message sequence
For more information about the <strong>IEEE</strong> <strong>1588</strong> st<strong>an</strong>dard, visit the web page for the National Institute of
St<strong>an</strong>dards <strong>an</strong>d Technology.
<strong>Implementing</strong> <strong>an</strong> <strong>IEEE</strong> <strong>1588</strong> <strong>V2</strong> <strong>Node</strong> on the MCF5441X, Rev. 0
t2
Example:
A = 106 – 101 = 5
B = 108 – 111 = -3
Delay = (5-3) / 2 = 1
Offset = (5+3) / 2 = 4
Equation 2:
t2 = timestamp
of delay_req msg sent
t3 – t2 = delay - offset
Slave Clock
G/MII PTP Appl.
t 1
t 2
A
Precise
Receive
Time (106)
Offset
Computation
Precise
Send Time
(111)
104
106
108
110
112
114
116
UDP port 319: Sync <strong>an</strong>d
Delay_Req
UDP port 320: Follow_up,
Delay_Resp, <strong>an</strong>d Mgmt
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