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PXA300 Processor and PXA310 Processor
Vol. I: System and Timer Configuration Developers Manual
Doc. No. MV-TBD-00 Rev. A
CONFIDENTIAL
Copyright © 12/13/06 Marvell
Page 50
Document Classification: Proprietary Information
December 13, 2006
Not approved by Document Control. For review only.
When the external system de-asserts nRESET, the processor de-asserts nRESET_OUT after a specified time, and
the processor then attempts to boot from physical address location 0x0000_0000, which always points to the
internal boot ROM. Code in the boot ROM is always, without exception, the first code that is executed.
Various internal-configuration values are used to steer the flow of operation of the boot ROM, allowing the
processor to boot from the data flash, the USB client, or a UART. Refer to the boot ROM specification for
detailed information.
In addition to being mapped at address 0x0000_0000, the boot ROM is also mapped at address 0x5C00_0000.
Once the boot operation has started, the software performs a jump operation to the 0x5C00_0000 address range
and continues to execute. Mapping to address 0x0000_0000 in the boot ROM is then disabled, allowing other
memory devices to be visible at address 0x0000_0000. Mapping to address 0x0000_0000 in the boot ROM is
re-enabled by any reset operation.
2.15
Memory Map and Register Overview
This section provides an overview of the PXA300 processor or PXA310 processor physical address map for
memory and memory-mapped registers. It also summarizes the registers within the independent coprocessors in
the processor core. Refer to individual unit chapters of the peripherals volume for the mapping of individual
registers.
All internal control and configuration registers are mapped in physical memory space on 32-bit address
boundaries. Use 32-bit word access loads and stores to access internal registers. Internal register space must be
mapped as non-cacheable. In general, many buffers and FIFOs can be accessed in byte, half-word, and word
sizes. Byte and half-word accesses to internal registers are not permitted and yield unpredictable results. Refer to
the individual peripheral chapters for specific information.
Register space where a register is not specifically mapped is defined as reserved space. Reading or writing
reserved space causes unpredictable results.
The PXA300 processor or PXA310 processor does not use all register bit locations. The unused bit locations are
marked reserved and are allocated for future use. Write reserved bit locations with 0b0. Ignore the values of these
bits during read operations, as they are unpredictable.
The physical memory map includes external memory, internal memory, and the memory-mapped internal
registers of the peripheral controllers. Services-unit registers are accessed indirectly through the peripheral
applications subsystem. Thus, the peripheral-register address map includes all services-unit registers for power
management, clock management, the PWR_I
2
C interface (which controls external supply regulators), and the
real-time clock. Software can use the memory management unit included in the core to map portions of this
physical address map to the virtual address map.
Note:
Accessing reserved portions of the memory map results in a data-abort exception. Accessing
reserved portions of a particular peripheral address space does not cause a data-abort exception,
but the data returned is undefined.
shows the address bit regions used for decoding memory blocks, applications subsystem units, and
applications subsystem sub-units from the physical address.