SA-1110/Applications Processor Migration

You must choose memory clocks, LCD clock rates, audio clocks and interfaces, which GPIOs are actually connected to hardware, and many more. There are no easy solutions here, the device space of the PXA250 applications processor is very diverse and a number of selections must be made in software to select your particular hardware functionality.

All software that controls registers will need to be updated. If a switch is connected to a GPIO, then the software that reads the switch register will differ between the PXA250 applications processor and SA-1110. This applies to software that controls Configuration registers in Coprocessor space and also to a number of the memory-mapped registers. Many functions such as memory timing configuration are done through these registers. For example the registers to access USB have a different name, address and function. Any code that directly accesses the USB hardware registers will need to be rewritten.

A.2.5 DMA

The SA-1110 contains a 6-channel DMA controller that pipes data between the serial channels and memory. The PXA250 applications processor provides a far more substantial 16-channel chained DMA controller that can be configured to do much more than the SA-1110, including memory-to- memory block moves.

Clearly there are changes in software required to take advantage of this new asset. However this also implies changes necessary to maintain similar functionality to the SA-1110. To configure a DMA channel you no longer set it to a specific serial port, instead you map it to the specific source or destination address of the serial port FIFO. You must configure other parameters for address incrementing and memory width that differ between the PXA250 applications processor and SA- 1110.

Any device driver using the SA-1110 DMA controller, or application that takes direct advantage of DMA, will need to be modified. The impact of this varies as some Operating Systems and many device drivers have ignored the SA-1110 DMA in favor of programmed I/O.

Some have argued to remove the required interrupt management code as they only move small blocks. Operating systems have excluded DMA to guarantee they can manage the real-time behavior of different threads. Other software providers saw the serial ports as so slow that DMA performance was unnecessarily complex.

The performance benefit of the PXA250 DMA controller is one of the most significant improvements over the SA-1110, particularly in the area of memory-to-memory moves. Changing code on the PXA250 applications processor to utilize the new DMA functionality will significantly enhance applications.

A.3 Using New PXA250 Features

This appendix doesn’t attempt to discuss all the differences between the PXA250 applications processor and the SA-1110 or it would become quite substantial. There are numerous significant advantages that the PXA250 applications processor has to offer, all of which potentially require changes in hardware, firmware or software development tools. This section lists just a few of the chief additional benefits of the PXA250 applications processor. However, refer to the product specifications for further details. This list is not comprehensive.

PXA250 and PXA210 Applications Processors Design Guide

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Intel PXA250 and PXA210 manual Using New PXA250 Features, 5 DMA
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PXA250 and PXA210 specifications

The Intel PXA250 and PXA210 processors, part of the Intel XScale architecture, were introduced in the early 2000s, targeting mobile and embedded applications. They are known for their low power consumption, high performance, and advanced multimedia capabilities, making them suitable for a wide range of devices, including PDAs, smartphones, and other portable computing devices.

The PXA250, which operates at clock speeds ranging from 400 MHz to 624 MHz, features a superscalar architecture that allows it to issue multiple instructions per clock cycle. This enhances the overall performance for demanding applications while maintaining low power usage. It supports a variety of peripheral interfaces, including USB, Ethernet, and various memory types, which contributes to its versatility in different product designs.

One of the key technologies in the PXA250 is the integrated Intel Smart Repeat Technology, which optimizes data processing, thereby reducing the amount of power consumed during operation. This feature is particularly important for battery-powered devices, as it extends the overall battery life, allowing for longer usage times in mobile environments. Additionally, the PXA250 includes a dedicated graphics acceleration unit, which enables enhanced graphics and multimedia performance suited to modern applications at the time.

In contrast, the PXA210 is a more entry-level processor, aimed at cost-sensitive applications. Operating at lower clock speeds, typically around 200 MHz to 400 MHz, it forgoes some of the advanced performance features of the PXA250 while still offering a good balance of performance and power efficiency. The PXA210 is less complex, making it suitable for simpler devices that do not require the extensive capabilities of the PXA250.

Both processors utilize the Intel XScale architecture, which is based on the ARM instruction set. They are built on a 0.13-micron process technology, enabling higher density and lower power consumption compared to their predecessors. With integrated memory controllers and bus interfaces, they facilitate efficient data handling and connectivity options.

In summary, both the Intel PXA250 and PXA210 processors played a crucial role in the evolution of mobile computing by providing powerful processing capabilities with energy efficiency. Their features and technologies enabled device manufacturers to create innovative products that catered to the growing demand for portable devices during that era.
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