USB Interface

detected. When an interrupt occurs, software must read the GPIOn pin to determine if the cable is connected or not. GPIOn is 1 if the cable is connected or 0 if the cable is disconnected. If a USB connect is detected, then software enables the UDC peripheral and drives a 1 onto the GPIOx pin to indicate to the host PC a fast USB device is connected. If a USB disconnect is detected, then software must configure the GPIOx pin as an input, configure the GPIOn pin to detect a wakeup event, and then put the part into sleep mode.

Also, at any time, you may use software to put the part into sleep mode. Before entering sleep mode, configure the GPIOx pin as an input to cause the UDC+ line to float. This looks like a disconnect to the host PC. The device can then be put into sleep mode. When the device becomes active, software must drive a 1 onto the GPIOx pin to indicate to the host PC a fast USB device has been connected.

4.1.2Operation if GPIOn and GPIOx are the Same Pin

Out of reset, GPIOn is configured as an input and configured to cause an interrupt whenever a rising or falling edge is detected. When an interrupt occurs, software must read the GPIOn pin to determine if the cable is connected or not. This pin is 1 if the cable is connected or 0 if the cable is disconnected. If the USB cable is connected, then software must enable the UDC peripheral before the host sends the first USB command. If the USB cable is not connected, then software must configure the GPIOn pin to detect a wakeup event, and then put the part into sleep mode.

4.2Bus Powered Device

The applications processor cannot support a bus powered device model. When the host sends a suspend, the device is required to consume less than 500 uA (Section 7.2.3 of the USB spec version 1.1). The applications processor cannot limit its current consumption to 500 uA unless it enters sleep mode. If it enters sleep mode, all USB registers are reset and it does not respond to its host- assigned address.

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PXA250 and PXA210 Applications Processors Design Guide

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Intel PXA250 and PXA210 manual Bus Powered Device, Operation if GPIOn and GPIOx are the Same Pin

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.