Flow control implementation rules – Altera SerialLite II Protocol User Manual
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Altera Corporation
63
SerialLite II Protocol Reference Manual
SerialLite II Specification
Flow Control Implementation Rules
The following flow control implementation rules must be followed:
1.
IDL characters are transmitted by the near transmitter during the
pause period.
2.
Flow control has no effect on management packets. Meaning that
link management packets can still be transmitted during the pause
period. It also means that there is no way to flow control link
management packets. If a flow control packet is received during the
transmission of a link management packet, the transmission of the
link management packet continues irrespective of the pause packet.
3.
If a flow control packet is received during a data packet transfer, the
near transmitter stops sending data immediately after the current
column is transmitted and flow control takes place. For a priority
packet, the near transmitter stops sending data immediately after
completion of the segment.
4.
The flow control timer must be refreshed with a new FC_TIME
before it expires, if the receiver is unable to accept new data.
shows a flow control example.
Figure 2–41. Flow Control Example
Time
D8
IDL
D 12
D 16
PD0
PD4
D0
D4
D9
IDL
D 13
IDL
PD1
PD5
D1
D5
D 10
SDP1
D 14
IDL
PD2
PD6
D2
D6
D 11
SDP2
D 15
IDL
PD3
PD7
D3
D7
CRC1
CRC2
EG P1
EG P2
SPP1
SPP2
IDL
IDL
Lane
# 0
Lane
# 1
Lane
# 2
Lane
# 3
CRC1
EG P1
CRC2
EG P2
CRC3
IDL
CRC4
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
Flow controlled
for FC_TIME