Altera SerialLite II Protocol User Manual
Page 59
Altera Corporation
59
SerialLite II Protocol Reference Manual
SerialLite II Specification
Figure 2–37. CRC Alignment for Eight Lanes
Breaking data packets is treated like the end-of-packet as the CRC is
appended to the two byte SUP sequence. The CRC is calculated over that
burst of user data. When the packet is resumed, the initial value used is
the all ones pattern as described below. This allows burst transfers to be
verified before the end-of-packet. As the CRC is computed on each burst
instead of the entire packet, saving of context is not required and the CRC
remainder is discarded making implementation simpler. Having the CRC
computed only over the burst is advantageous for systems using large
packet sizes or susceptible to high bit error rates.
Figure 2–38. SUP Sequence followed by CRC
Time
D8
IDL
D 12
D 16
PD0
PD4
D0
D4
D9
IDL
D 13
PD1
PD5
D1
D5
D 10
D 14
PD2
PD6
D2
D6
D 11
D 15
PD3
PD7
D3
D7
CRC1
CRC2
CRC3
CRC4
EG P1
EG P2
SPP1
SPP2
IDL
EG P1
IDL
EG P2
SDP1
IDL
SDP2
IDL
IDL
IDL
IDL
IDL
IDL
Lane
# 0
Lane
# 1
Lane
# 2
Lane
# 3
Lane
# 4
Lane
# 5
Lane
# 6
Lane
# 7
IDL
IDL
IDL
IDL
IDL
IDL
IDL
IDL
CRC-32
D8
IDL
D 12
D0
D4
D9
IDL
D 13
D1
D5
D 10
SDP1
D 14
D2
D6
D 11
0 0
D 15
D3
D7
D8
SUP1
D 12
D0
D4
D9
0 0
D 13
D1
D5
D 10
SDP1
D 14
D2
D6
D 11
0 1
D 15
D3
D7
SUP1
0 1
CDP1
0 0
D 16
IDL
IDL
IDL
EG P1
0 0
CDP1
0 1
D 16
IDL
IDL
IDL
EG P1
0 1
IDL
IDL
Lane
# 0
Lane
# 1
Lane
# 2
Lane
# 3
CRC1
CRC2
CRC3
CRC4
CRC1
CRC2
CRC3
CRC4
CRC1
CRC2
CRC3
CRC4
CRC1
CRC2
CRC3
CRC4
Time
Suspended packet
followed by CRC-32
Suspended packet
followed by CRC-32