Intel PXA270, Optimization Manual

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1-6 Intel® PXA27x Processor Family Optimization Guide
Introduction
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The system bus can operate at different frequency ratios with respect to the Intel XScale® core
(up to 208 MHz). The frequency control of the system bus is pivotal to striking a balance
between the desired performance and power consumption.
1.2.5.2 Peripheral Bus
The peripheral bus is a single master bus. The bus master arbitrates between the Intel XScale® core
and the DMA controller with a pre-defined priority scheme between them. The peripheral bus is
used by the low-bandwidth peripherals; the peripheral bus runs at 26 MHz.
1.2.5.3 Peripherals in the Processor
The PXA27x processor has a rich set of peripherals. The list of peripherals and key features are
described in the subsections below.
1.2.5.3.1 LCD Display Controller
The LCD controller supports single- or dual-panel LCD displays. Color panels without internal
frame buffers up to 262144 colors (18 bits) are supported. Color panels with internal frame buffers
up to 16777216 colors (24 bits) are supported. Monochrome panels up to 256 gray-scale levels
(8 bits) are supported.
1.2.5.3.2 DMA Controller
The PXA27x processor has a high performance DMA controller supporting memory-to-memory
transfers, peripheral-to-memory and memory-to-peripheral device transfers. It has support for
32 channels and up to 63-peripheral devices. The controller can perform descriptor chaining. DMA
supports descriptor-fetch, no-descriptor-fetch and descriptor-chaining.
1.2.5.3.3 Other Peripherals
The PXA27x processor offers this peripheral support:
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USB Client Controller with 23 programmable endpoints (compliant with USB Revision 1.1).
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USB Host controller (USB Rev. 1.1 compatible), which supports both low-speed and full-
speed USB devices through a built-in DMA controller.
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Intel® Quick Capture Interface which provides a connection between the processor and a
camera image sensor.
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Infrared Communication Port (ICP) which supports 4 Mbps data rate compliant with Infrared
Data Association (IrDA) standard.
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I
2
C Serial Bus Port, which is compliant with I
2
C standard (also supports arbitration between
multiple-masters).
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AC97 CODEC Interface (compliant with AC97 2.0) supporting multiple independent channels
(different channels are used for stereo PCM In, stereo PCM Out, MODEM Out, MODEM-In
and mono Mic-in).
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I
2
S Audio CODEC Interface.
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Three flexible synchronous serial ports.
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Multimedia Card Controller supports the MMC, SD and SDIO protocols.
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The PXA27x processor supports three UARTs compatible with 16550 and 16750 standard.