Filter
Top Products
74 www.xilinx.com SPI-4.2 Lite v4.3 User Guide
UG181 June 27, 2008
Chapter 4: Designing with the Core
R
• SnkBusErrStat[5]: Control word with payload bit not set and non-zero address
(excluding Training Control word)
• SnkBusErrStat[7:6]: Unused and tied to zero (reserved)
If the core receives two (or more) back-to-back payload control words, the last one received
is used and others are discarded. If the core receives two (or more) back-to-back EOP
control words, the first one is used and the others are discarded. Any of the error
conditions that flag the Sink Bus Error Status bus also flags SnkBusErr.
Sequential Payload Control Words
If back-to-back payload control words are sent, the Sink core only uses the payload control
word that precedes a data word. All other payload control words are dropped by the Sink
core. Each time a payload control word is dropped, it is flagged on SnkBusErr. This
behavior is illustrated in Figure 4-17.
Sequential End-of-Burst Control Words
The Sink core only stores the end-of-burst control word that was preceded by data. It drops
any other end-of-burst control words that are not preceded by data and flags SnkBusErr.
Figure 4-17 illustrates this behavior.
Sink DIP-4 Error Handling
When a DIP-4 error occurs at the end of a burst (for the previous packet), the Sink core
stores a SnkFFDIP4Err flag. Figure 4-18 illustrates a DIP-4 error that occurred on an end-of-
packet control word.
Figure 4-17: Sequential Payload Control Word Example
Ch 1
SOP
Ch 2
SOP
Ch 3
SOP
DATA
Ch 3
EOP
Ch 2
EOP
Ch 1
EOP
Dropped:
SnkBusErr
(flagged
two times)
Good Packet
Bit
Bucket
Dropped:
SnkBusErr
(flagged
two times)
Bit
Bucket
SPI-4.2 Interface
User Interface:
Addr3
SOP
Data
Addr3
--
Data
Addr3
EOP
Data
Addr0
SOP
Data
. . .
DATA DATA DATA
Ch 0
SOP
Addr3
--
Data