LSI Logic Confidential
10-2
Host Async Master Interface
Copyright © 2001, 2002 by LSI Logic Corporation. All rights reserved.
10.2 Host (Slave) plus Limited Master
In this configuration (MCONFIG = 01), the master interface pins are
separate from the host slave interface pins. The master space is
swapped with the DRAM space in the SPARC address map, changing
the start of SDRAM to zero. The SCPU rst bit will remain set after reset
to allow the host processor to download microcode before booting. In this
configuration, only self-paced SDRAM signals are possible and only one
chip select, M_CS[0], is available.
The upper and lower order address and control pins other than M_ALE
(M_ADDR[26:22], M_ADDR[5:1], M_CS[0], M_OE, M_RD/WR) replace
serial I/O pins for UART1, SPI and IR transmit (UART2, IR receive, and
IDC are still available). The master interface pins
M_ADDR[21:6]/M_D[15:0] are shared with ATAPI_DATA[15:0] pins when
the storage interface is in ATAPI mode and
SD_DATA[7:0]/SBP_DATA[7:0] when the storage interface is in SD mode.
Since the master and ATAPI control lines are separate, both may operate
concurrently.
ATAPI cycles are round robin arbitrated with master interface cycles. SD
and secondary bitstream transfers can not be interrupted. Consequently
SPARC master accesses will generate a host error and Master DMA
accesses will abort the DMA operation when the SD DMA or Secondary
Bitstream DMA GO bits are on. (See
Status/Time-Out Register,” page 10-17
.)
10.3 Master Replaces Slave
In this configuration (MCONFIG = 10), master interface pins replace
slave interface pins. The master space is at zero of the SPARC address
map, and the SCPU rst bit is cleared after reset, causing the system
SPARC to begin fetching instructions from a PROM at address zero.
Содержание DMN-8600
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