
Chapter 10. Chip-Select Module
10-9
Chip-Select Registers
10.4.1.4 Code Example
The code below provides an example of how to initialize the chip-selects. Only chip selects
0, 1, 2, and 3 are programmed here; chip selects 4, 5, 6, and 7 are left invalid. MBARx
denes the base of the module address space.
CSAR0 EQU MBARx+0x080
;Chip select 0 address register
CSMR0 EQU MBARx+0x084
;Chip select 0 mask register
CSCR0 EQU MBARx+0x08A
;Chip select 0 control register
CSAR1 EQU MBARx+0x08C
;Chip select 1 address register
CSMR1 EQU MBARx+0x090
;Chip select 1 mask register
CSCR1 EQU MBARx+0x096
;Chip select 1 control register
CSAR2 EQU MBARx+0x098
;Chip select 2 address register
CSMR2 EQU MBARx+0x09C
;Chip select 2 mask register
CSCR2 EQU MBARx+0x0A2
;Chip select 2 control register
CSAR3 EQU MBARx+0x0A4
;Chip select 3 address register
CSMR3 EQU MBARx+0x0A8
;Chip select 3 mask register
CSCR3 EQU MBARx+0x0AE
;Chip select 3 control register
CSAR4 EQU MBARx+0x0B0
;Chip select 4 address register
CSAR4 EQU MBARx+0x0B4
;Chip select 4 mask register
CSMR4 EQU MBARx+0x0BA
;Chip select 4 control register
8
AA
Auto-acknowledge enable. Determines the assertion of the internal transfer acknowledge for
accesses specied by the chip-select address.
0 No internal TA is asserted. Cycle is terminated externally.
1 Internal TA is asserted as specied by WS. Note that if AA = 1 for a corresponding CS
n and the
external system asserts an external TA before the wait-state countdown asserts the internal TA, the
cycle is terminated. Burst cycles increment the address bus between each internal termination.
7–6
PS
Port size. Species the width of the data associated with each chip select. It determines where data
is driven during write cycles and where data is sampled during read cycles. See
Section 10.3.1.1,00 32-bit port size. Valid data sampled and driven on D[31:0]
01 8-bit port size. Valid data sampled and driven on D[31:24]
1x 16-bit port size. Valid data sampled and driven on D[31:16]
5
BEM
Byte enable mode. Species the byte enable operation. Certain SRAMs have byte enables that must
be asserted during reads as well as writes. BEM can be set in the relevant CSCR to provide the
appropriate mode of byte enable in support of these SRAMs.
0 Neither BE nor BWE is asserted for read. BWE is generated for data write only.
1BE is asserted for read; BWE is asserted for write.
4
BSTR
Burst read enable. Species whether burst reads are used for memory associated with each CS
n.
0 Data exceeding the specied port size is broken into individual, port-sized non-burst reads. For
example, a longword read from an 8-bit port is broken into four 8-bit reads.
1 Enables data burst reads larger than the specied port size, including longword reads from 8- and
16-bit ports, word reads from 8-bit ports, and line reads from 8-, 16-, and 32-bit ports.
3
BSTW Burst write enable. Species whether burst writes are used for memory associated with each CS
n.
0 Break data larger than the specied port size into individual port-sized, non-burst writes. For
example, a longword write to an 8-bit port takes four byte writes.
1 Enables burst write of data larger than the specied port size, including longword writes to 8 and
16-bit ports, word writes to 8-bit ports and line writes to 8-, 16-, and 32-bit ports.
2–0
—
Reserved, should be cleared.
Table 10-10. CSCRn Field Descriptions
Bits
Name
Description