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Process for converting frequency of central processing unit

A central processing unit and frequency technology, applied in the direction of data processing power supply, etc., can solve problems such as abnormal display of LCD screens

Inactive Publication Date: 2005-07-20
HTC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

During the frequency change of the internal bus PXBus, the Phase Lock Loop (PLL) inside the PXA250 is disabled, so the PXA250 does not output the pixel clock (pixel clock) to the LCD screen, causing the LCD screen to display incorrectly. normal

Method used

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  • Process for converting frequency of central processing unit
  • Process for converting frequency of central processing unit
  • Process for converting frequency of central processing unit

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Embodiment Construction

[0020] During the process of changing the frequency of the central processing unit of the Xscale series, the phase lock frequency loop (Phase LockLoop, PLL) is disabled (disabled), thus causing the display glitch of the LCD screen. According to the actual measurement results, when the frequency of the internal bus PXBus of the PXA250 processor of the Xscale series changes, the PLL will pause for about 335μs. The frame buffer in the PXA250 processor is 128 bytes (byte). Under normal circumstances, the pixel clock (pixel clock) is 4.54MHz, and the length of time the frame buffer can display is (128 / 2)*( 1 / 4.54MHz) = 14.1μs. Since 14.1μs is shorter than the PLL pause time of 335μs, the data in the picture buffer is used up after 14.1μs, and new data cannot be provided to the LCD screen, thus causing the LCD screen to display abnormally.

[0021] The spirit of the present invention is to reduce the pixel clock to below 191KHz before switching the processor frequency, so that the ...

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Abstract

The invention discloses a method for changing the frequency of the central processing unit, used for changing the operating frequency of a central processing unit from a first frequency to a second frequency, the electronic installation includes a display screen and a central processing unit, wherein the display screen displays the image in accordance with a pixel clock outputted by the central processing unit. And the method comprises, lowering the pixel clock frequency, transforming the frequency for the central processing unit, and resuming the pixel clock frequency.

Description

technical field [0001] The invention relates to a method for changing the frequency of a central processing unit, in particular to a method for changing the frequency of the central processing unit of XScale series of Intel Corporation. Background technique [0002] The central processing unit of Intel's Xscale architecture (microarchitecture), such as the PXA250 or PXA210 processor, has the advantages of power saving, small size, and high integration, and is suitable for embedded systems (Embedded System) or portable systems. An example is a Personal Digital Assistant (PDA). Taking the PXA250 processor as an example, its operation modes include Turbo mode, Run mode and Idle mode. In spray mode, the PXA250 processor operates at a maximum frequency of 400MHz; in run mode, the PXA250 processor operates at a minimum frequency of 100MHz. Taking PDA as an example, when the user does not operate for a period of time, the PDA can enter the idle mode to save power consumption, and...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06F1/32
Inventor 许世明许自勇李吉丰徐世川官宗緥陈逸洲
Owner HTC CORP