PowerPC™ 405 Processor Block Reference Guide www.xilinx.com 95
UG018 (v2.0) August 20, 2004 1-800-255-7778
R
DSPLB 2:1 Core-to-PLB Line Read

The timing diagram in Figure 2-26 shows a line read in a system with a PLB clock th at runs

at one half the frequency of the PowerPC 405 clock.

The line read (rl1) is requested by the DCU in PLB cycle 2, which corresponds to PowerPC

405 cycle 3. The BIU responds in the same cycle. Data is sent from the BIU to the DCU fill

buffer in PLB cycles 3 through 6 (PowerPC 405 cycles 5 through 12). After all data

associated with this line is read, it is transferred by the DCU from the fill buffer to the data

cache. This is represented by the fill1 transaction in PowerPC 405 cycles 13 through 15.

Figure 2-25: DS PLB Word Write/Line Read/Line Write

Cycle 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
PLBCLK an d CPMC40 5CLK
UG018_29_101701
PPC405 Outputs:
C405PLBDCUREQUEST
C405PLBDCURNW
C405PLBDCUABUS[0:31] adr1 adr2 adr3
val
d1
C405PLBDCUBE[0:7]
C405PLBDCUWRDBUS[0:63]
C405PLBDCUSIZE2
PLB/BIU Outputs:
PLBC405DCUADDRACK
PLBC405DCURDDBUS[0:63]
PLBC405DCURDWDADDR[1:3]
PLBC405DCURDDACK
PLBC405DCUWRDACK
PLBC405DCUBUSY
DCU
ww1
rl2ww1 wl3
rl2ww1 wl3
rl201 rl223 rl245 rl267
wl301wl323wl345wl367
d201 d223 d245 d267
d301 d323 d345 d367
0246
flush3 fill2