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96 www.xilinx.com SPI-4.2 Lite v4.3 User Guide
UG181 June 27, 2008
Chapter 4: Designing with the Core
R
Error Handling
This section describes how the Source core handles the receipt of non-compliant SPI-4.2
data and subsequent error handling in a number of common scenarios. This section also
provides additional information on the Source core error status signals.
Source Behavior Before Synchronization
• To go into frame, the Source core must receive the number of complete status
sequences defined by NumDip2Matches.
♦ Each received status sequence must contain the correct number of entries (defined
by SrcCalendar_Len* SrcCalendar_M) followed by the DIP-2 calculation and
a frame word "11."
• When the core is out of sync, it will resychronize to the first "11-to-non-11" transition.
Once it receives this transition, it will go in-frame once it receives the expected
number of correct consecutive DIP-2 words.
• If there is a calendar mismatch with the receiving device, the core may not go into
frame. If the mismatch causes DIP-2 errors, then SrcDIP2Err will be asserted.
• When the core is out of frame, every "11-to-non-11" transition is considered as a start
of status sequence.
• The core checks if a "11" is received after an expected DIP-2 value is received. If a non
”11” frame word is received the SrcStatFrameErr signal will assert.
Source Behavior After Synchronization
• If the core receives an incorrect DIP-2 word, SrcDIP2Err flag will be asserted.
• If the core receives an incorrect frame word (not “11”), the SrcStatFrameErr flag
will assert. This is another indication that the calendar is mismatched.
• After a specified number of consecutive DIP-2 Errors (defined by NumDip2Errors),
the Source core will go out-of-frame.
• If the Source core receives four consecutive frame words ("11"), it will go out-of-frame.
• Once in frame, the core does not realign to the beginning of a status sequence. The
assertion of DIP-2 errors would indicate a possible mismatch with the calendar of the
receive device.
• A mismatch with the calendar of the receive device can be detected by polling that
you have received a "11" as status on SrcStat.
EOP Abort Insertion
An EOP Abort will be inserted when a burst termination on a non-credit boundary without
an EOP is followed by an SOP or an address change.
If a burst is paused on a non-credit boundary and then resumed with data (without an
SOP) from the same channel, an EOP abort will not be inserted.
Source Out of Frame
Source Out of Frame (SrcOof) is asserted when the Source core is out-of-frame. The
following cases can cause the Source core to go out-of-frame:
• Case 1: You reset the core by asserting Reset_n.