2-2 Intel® PXA255 Processor Developer’s Manual
System Architecture
2.2 Intel® XScale™ Microarchitecture Implementation Options

The processor incorporates the Intel® XScale™ microarchitecture which is described in a separate

document. This core contains implementation options which an Application Specific Standar d

Product (ASSP) may elect to implement or omit. This section describes those options.

Most of these options are specified within the coprocessor register space. The processor does not

implement any coprocessor registers beyond those defined in the Intel® XScale™

microarchitecture. The coprocessor registers which are ASSP specific, as stated in the Intel®

XScale™ Microarchitecture for the Intel® PXA255 Processor User’s Manual, order number

278793, are defined in the following sections.

2.2.1 Coprocessor 7 Register 4 - PSFS Bit

Bit 5 of this register is defined a s t he P ower So urc e Fa ult S t atu s bit or PSF S bit . This b it is s et when

either nVDD_FAULT or nBATT_FAULT pins are asserted and the Imprecise Data Abort Enable

(IDAE) bit in the Power Manager Control Register (PMCR) is set.

This is a read-onl y register. Ignore reads fro m reserved bits.

Figure 2-1. Block Diagram

IntelÆ XScaleô
Microarchitecture
Color or
Grayscale
LCD
Controller
RTC
OS Timer
PWM(2)
Int.
Controller
Clocks &
Power Man.
I2S
AC97
UARTs
NSSP
Slow IrDA
SSP
USB
Client
General Purpose I/O
ASIC
Socket 0
Socket 1
3.6864
MHz
Osc
32.768
KHz
Osc
DMA Controller
and Bridge
XCVR
SDRAM/
SMROM
4 banks
ROM/
Flash/
SRAM
4 banks
I2C
Fast IrDA
MMC
Peripheral Bus
System Bus
Memory
Controller
Variable
Latency I/O
Control
PCMCIA
& CF
Control
Dynamic
Memory
Control
Static
Memory
Control