6-74
Intel® PXA255 Processor
Developer’s Manual
Memory Controller
is deasserted or, as part of the sleep entry routine, the alternate master can be disabled. If necessary,
the alternate master can hold the bus until its transaction is completed. After the memory controller
has completed all outstanding transactions, it places SDRAM into self-refresh and allows the
processor to complete the sleep entry sequence.
Note:
The alternate bus master must de-assert MBREQ when nVDD_FAULT or nBATT_FAULT is
asserted.
6.10
Options and Settings for Boot Memory
This section explains the settings that control Boot Memory configurations.
6.10.1
Alternate Booting
The processor allows six boot configurations. These configurations are determined by the three
BOOT_SEL(2:0) pins and are described in
Table 6-39
. A description of the effect of these input
pins on the Configuration registers at boot time is included in
Section 6.8
.
6.10.2
Boot Time Defaults
The following sections provide information on boot time default parameters.
6.10.2.1
BOOT_DEF Read-Only Register (BOOT_DEF)
BOOT_DEF, shown in
Table 6-40
, contains the boot-up values for the three BOOT_SEL pins and
the single package-type bit.
This is a read-only register. Ignore reads from reserved bits.
Table 6-39. BOOT_SEL Definitions
BOOT_SEL
Boot From...
2
1
0
0
0
0
Asynchronous 32-bit ROM
0
0
1
Asynchronous 16-bit ROM
0
1
0
reserved
0
1
1
reserved
1
0
0
1- 32-bit Synchronous Mask ROM (64 Mbit)
2- 16-bit Synchronous Mask ROMs = 32 bits (32 Mbit each)
1
0
1
1- 16-bit Synchronous Mask ROM (64 Mbit)
1
1
0
2- 16-bit Synchronous Mask ROMs = 32 bits (64 Mbit each)
1
1
1
1- 16-bit Synchronous Mask ROM (32 Mbit)
Summary of Contents for PXA255
Page 1: ...Intel PXA255 Processor Developer s Manual January 2004 Order Number 278693 002 ...
Page 24: ...xxiv Intel PXA255 Processor Developer s Manual Contents ...
Page 30: ...1 6 Intel PXA255 Processor Developer s Manual Introduction ...
Page 310: ...7 46 Intel PXA255 Processor Developer s Manual LCD Controller ...
Page 330: ...8 20 Intel PXA255 Processor Developer s Manual Synchronous Serial Port Controller ...
Page 358: ...9 28 Intel PXA255 Processor Developer s Manual I2 C Bus Interface Unit ...
Page 488: ...13 36 Intel PXA255 Processor Developer s Manual AC 97 Controller Unit ...
Page 572: ...16 30 Intel PXA255 Processor Developer s Manual Network SSP Serial Port ...
Page 599: ...Intel PXA255 Processor Developer s Manual 17 27 Hardware UART ...
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