158 www.xilinx.com PowerPC™ 405 Processor Block Reference Guide
1-800-255-7778 UG018 (v2.0) August 20, 2004
Chapter 3: PowerPC 405 OCM Controller
R
Note: See Tabl e 3-8 for descriptions of the signals shown in Tabl e 3-10 , above.
Programmer’s Model

DCR Registers

Application software has read and write access to the DCR control registers within the
OCM controllers. Typically , mtdcr and mfdcr assembly lan guage i nstruc tions a re used t o
write and read respectively from these registers.
Figure 3-11, page162 and Figure 3-12, pag e 163 list the DCR control registers and the bit
definitions for the DSOCM interface for Virtex-II Pro and Virtex-4. Figure 3-13, page 164
and Figure 3-14, page 165 list the DCR control registers and the bit definitions for the
ISOCM interface for Virtex-II Pro and Virtex-4.

DSARC/ ISARC Registers

The ISOCM and DSOCM interfaces provide DCR registers (DSARC & ISARC) which
define the eight most significant (base) address bits of the ISOCM and DSOCM memory

Figure 3-10: ISOCM to BRAM Interface: 8 KByte Example in Virtex-4

UG018_49b_04230
4
ISOCMBRAMRDABUS[19:28]
BRAMISOCMRDDBUS[0:63]
ISOCMBRAMEN
BRAMISOCMCLK
ISOCMBRAMWRDBUS[0:31]
ISOCMBRAMWRABUS[19:28]
ISOCMDCRBRAMRDSELECT
ISOCMBRAMODDWRITEEN
ISOCMBRAMEVENWRITEEN
ISOCMDCRBRAMODDEN
ISOCMDCRBRAMEVENEN
BRAMISOCMDCRRDBUS[0:31]
ISCNTLVALUE[0:7]
ISARCVALUE[0:7]
ADDRB[9:0]
DOB[15:0]
WEB
CLKB
ENB*
SSRB
(RAMB16S18S18) X 4
(2 for Odd words, 2 for Even)
ADDRA[13:4]
PORT B
PORT A
DIA[15:0]
WEA
CLKA
ENA*
SSRA
DOA(odd)
DOA(even)
(BRAMISOCMCLK from DCM)
*ENA can be tied off
permanently for higher
performance.
Global signals from FPG
A
system interface