PowerPC™ 405 Processor Block Reference Guide www.xilinx.com 97
UG018 (v2.0) August 20, 2004 1-800-255-7778
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DSPLB Aborted Data-Access Request
The timing diagram in Figure2-28 shows an aborted data-access request. The request is
aborted because of a core reset. The BIU is not reset.
A line write (wl1) is requested by the DCU in cycle 3 in response to a cache flush
(represented by the flush1 transacti on in cycl es 1 thr ough 2). T he BIU res ponds in t he same
cycle the request is made by the DCU. Data is sent from the DCU to the BIU in cycles 3
through 6.
A line read (rl2) is address pipelined with the previous line write. The rl2 request is made
by the DCU in cycle 5 and the BIU responds in the same cycle. However, the processor also
aborts the request in cycle 5. Therefore, no data is transferred from the BIU to the DCU in
response to this reques t.
Because the BIU is not reset, it must complete the first line write even though the processor
asserts the PLB abort signal during the line write.

Figure 2-27: DSPLB 3:1 Core-to-PLB Line Write

Cycle 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
CPMC40 5CLK
UG018_31_101701
PPC405 Outputs:
C405PLBDCUREQUEST
C405PLBDCURNW
C405PLBDCUABUS[0:31] adr1
flush1
C405PLBDCUBE[0:7]
C405PLBDCUWRDBUS[0:63]
C405PLBDCUSIZE2
DCU
wl1
d101 d123 d145 d167
PLBCLK
PLB/BIU Outputs:
PLBC405DCUADDRACK
PLBC405DCURDDBUS[0:63]
PLBC405DCURDWDADDR[1:3]
PLBC405DCURDDACK
PLBC405DCUWRDACK
PLBC405DCUBUSY
wl1
wl101 wl123 wl145 wl167