System Architecture

Figure 2-1. Block Diagram

RTC

OS Timer

PWM(2)

 

Int.

 

 

Controller

 

 

Clocks &

 

 

Power Man.

Bus

 

I2S

PurposeI/O

Peripheral

AC97

 

I2C

 

General

UARTs

 

 

 

 

NSSP

 

 

Slow IrDA

 

Fast IrDA

SSP

USB

Client

MMC

DMA Controller and Bridge

Color or

Grayscale

LCD

Controller

System Bus

Intelfi XScale

Microarchitecture

3.6864 32.768

MHz KHz

Osc Osc

Memory

Controller

Variable

 

Latency I/O

ASIC

Control

 

PCMCIA

XCVR

Socket 0

& CF

Socket 1

Control

 

 

Dynamic

 

 

 

 

SDRAM/

 

 

SMROM

Memory

 

 

 

 

 

 

 

 

 

 

4 banks

Control

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Static

 

 

 

 

ROM/

 

Flash/

Memory

 

 

 

 

 

 

 

SRAM

Control

 

 

 

 

 

4 banks

 

 

 

 

 

 

 

 

 

 

 

2.2Intel 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 Standard 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.

2.2.1Coprocessor 7 Register 4 - PSFS Bit

Bit 5 of this register is defined as the Power Source Fault Status bit or PSFS bit. This bit is set 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-only register. Ignore reads from reserved bits.

2-2

Intel® PXA255 Processor Developer’s Manual

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Intel PXA255 manual Intel XScale Microarchitecture Implementation Options, Coprocessor 7 Register 4 Psfs Bit