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SPI-4.2 Lite v4.3 User Guide www.xilinx.com 95
UG181 June 27, 2008
Source Core
R
RESET
The Source core remains in the RESET state until the Reset_n signal is deasserted. When
in the RESET state, the Source core transmits idle patterns on TDat[15:0] and the Status
FIFO is driven to be satisfied (“10”) for all channels.
HUNT
When Reset_n is deasserted, the state machine goes to the HUNT state and sends
continuous training patterns on the SPI-4.2 Interface. Once the Source core is enabled
(SrcEn=1), the Source Status Interface attempts to acquire synchronization on the FIFO
Status Channel. When the Source Status Interface has found the “11” framing pattern, the
Source core and monitors for the programmed number of consecutive DIP-2 correct
matches (NumDip2Matches). When in the HUNT state, the Status FIFO is driven to be
satisfied (“10”) for all channels.
SYNC
If the number of correct DIP-2 matches are received (NumDip2Matches), the Source core
goes into the SYNC state. In this state, the core transmits the flow control data received on
the status path (TStat[1:0]) onto the user interface. It also transmits the data that has
been written into the FIFO on the SPI-4.2 Lite data bus (TDat[15:0]). If an incorrect
framing pattern (of four consecutive "11") is received, a set number of consecutive DIP-2
errors (defined by NumDip2Errors) are received, or if SrcEn is deasserted, the state
machine returns to the HUNT State.
Figure 4-37: Source Startup Sequence State Machine
<NumDip2Errors> Consecutive
Incorrect DIP-2 Calculations Deleted
or Source Disabled
Reset Asserted
Reset Asserted
The Source core remains in the reset state
until the following condition is true:
Reset_n is deasserted
The source core transmits idle patterns
on TDat[15:0] while in the reset state.
The Source core remains in the hunt state
until the following conditions are:
-- The PHY device is no longer sending
framing (TSTAT /= "11")
-- Once framing is not being received, a
consecutive number of DIP2 matches
(defined by the parameter
<NumDip2Matches> is received.
-- Source is enabled
Each "11" to non "11" transition is
translated as a start of a status sequence.
The source core transmits training patterns
on TDat[15:0] while in the hunt state.
In the sync state, the Source core has
completed the start-up sequence and
normal core operation is enabled.
In normal operation, the Source core
transmits data bursts that have been
written into the Source FIFO. It also
sends periodic training patterns on TDat
and continuously checks DIP-2 parity
on TStat.
RESET
HUNT SYNC