本文以一個PDA項目為依托,在項目中,主要是開發(fā)該設備的軟件。其工作包括：上層應用程序的開發(fā)、引導程序的編寫、Linux操作系統(tǒng)的移植和各種外設驅(qū)動程序的編寫以及文件系統(tǒng)的改進。 本文首先分析了Linux操作系統(tǒng)的虛擬文件系統(tǒng)、高速緩沖區(qū)、MTD以及驅(qū)動程序模塊。接著,本文分析了JFFS2文件系統(tǒng)的不足,以及在大容量閃存設備中掛載速度過慢的原因。然后,本文結(jié)合JFFS2文件系統(tǒng)在開發(fā)過程中所出現(xiàn)的各種問題,以及在大容量閃存芯片上進行掛載時的性能要求,對JFFS2文件系統(tǒng)作了一些實際的改進。文中的創(chuàng)新性貢獻包括以下幾個方面： (1)在掃描一個擦除塊之前,首先把擦除塊中的所有內(nèi)容讀進內(nèi)存。然后,在內(nèi)存中進行所有的判斷操作以及拷貝,這樣就可以減少I/O操作。另外,由于所有的拷貝操作都在內(nèi)存中進行,所以掛載速度就可以有所提升。 (2)通過加入“空閑區(qū)域管理節(jié)點”對閃存中的空閑區(qū)域進行管理。這樣,在掃描的過程中,一旦發(fā)現(xiàn)該節(jié)點就可以跳過它所描述的空閑區(qū)域,從而加快掛載的速度。 (3)在掃描的階段中對有效數(shù)據(jù)實體進行硬鏈接數(shù)的計算,因此,臨時目錄節(jié)點就不需要創(chuàng)建了,這樣也免除了臨時目錄的刪除步驟,所以對掛載速度也有明顯的提高。 最后,基于以上的研究與改進,結(jié)合本項目的實際要求,對大容量閃存設備的JFFS2文件系統(tǒng)的掛載過程進行了改進的實踐。
上傳時間： 2013-07-26
上傳用戶：damozhi
Ti LaunchPad_Temp_GUI for your reference Select COM port that LaunchPad is connected to * receive serial communication from LaunchPad for * instantaneous temperature readings.
上傳時間： 2013-04-24
上傳用戶：ljt101007
雷達信號處理是雷達系統(tǒng)的重要組成部分。在數(shù)字信號處理技術飛速發(fā)展的今天，雷達信號處理中也普遍使用數(shù)字信號處理技術。而現(xiàn)場可編程門陣列(FPGA)在數(shù)字信號處理中的廣泛應用，使得FPGA在雷達信號處理中也占據(jù)了重要地位。 針對雷達信號處理的設計與實現(xiàn)，本文在以下兩個方面展開研究： 一方面以線性調(diào)頻信號(LFM)為例，分別對幾種基本的雷達信號處理，如正交相干檢波、脈沖壓縮、動目標顯示(MTI)/動目標檢測(MTD)和恒虛警(CFAR)詳細地闡述了其原理，在此基礎上給出了其經(jīng)常采用的實現(xiàn)方法，并在MATLAB環(huán)境中對各個環(huán)節(jié)進行了參數(shù)化仿真，詳盡地給出了各環(huán)節(jié)的仿真波形圖。針對仿真結(jié)果，直觀形象地說明了不同實現(xiàn)方法的優(yōu)劣。 另一方面結(jié)合MATLAB仿真結(jié)果，給出利用FPGA實現(xiàn)雷達信號處理的方案。在Xilinx ISE6.3i軟件集成環(huán)境下，通過對Xilinx提供的IP核的調(diào)用，并與VHDL語言相結(jié)合，完成雷達信號處理的FPGA實現(xiàn)。
標簽： FPGA 雷達信號 處理系統(tǒng)
上傳時間： 2013-04-24
上傳用戶：ylwleon
We would like to welcome you as a user of the Allegro CX, a rugged, handheld fi eld PC for data collection. Developed with the input of data collection professionals worldwide, the Allegro CX is adaptable and versatile for use in a wide variety of data collection environments. The Allegro CX continues to utilize our ergonomic, lightweight design that is standard in our line of Allegro Field PCs. This design makes your Allegro easy to use for extended periods while moving to and from data collection sites in the fi eld.
上傳時間： 2014-12-23
上傳用戶：gaojiao1999
Abstract: Transimpedance amplifiers (TIAs) are widely used to translate the current output of sensors like photodiode-to-voltagesignals, since several circuits and instruments can only accept voltage input. An operational amplifier with a feedback resistor fromoutput to the inverting input is the most straightforward implementation of such a TIA. However, even this simple TIA circuit requirescareful trade-offs among noise gain, offset voltage, bandwidth, and stability. Clearly stability in a TIA is essential for good, reliableperformance. This application note explains the empirical calculations for assessing stability and then shows how to fine-tune theselection of the feedback phase-compensation capacitor.
標簽： Transimpedance Stabilize Amplifier Your
上傳時間： 2013-11-13
上傳用戶：daoyue
Abstract: Using a wafer-level package (WLP) can reduce the overall size and cost of your solution.However when using a WLP IC, the printed circuit board (PCB) layout can become more complex and, ifnot carefully planned, result in an unreliable design. This article presents some PCB designconsiderations and general recommendations for choosing a 0.4mm- or 0.5mm-pitch WLP for yourapplication.
標簽： Considerations Guidelines and Design
上傳時間： 2013-10-14
上傳用戶：ysystc699
Abstract: How smart is your LED lighting system? While LED lighting holds the promise of reducingenergy consumption and maintenance costs, smart LED lighting designs improve system performance in
上傳時間： 2013-11-15
上傳用戶：13162218709
Removing output capacitors saves money and boardspace. Linear Technology’s OPTI-LOOPTM architectureallows you to use the output capacitors of your choice andcompensate the control loop for optimum transientresponse and loop stability. Figure 1 shows the dramaticimprovement possible with the OPTI-LOOP architecture.With the improvement shown in Figure 1, less capacitance
標簽： OPTI-LOOP 架構(gòu) 輸出電容 瞬態(tài)響應
上傳時間： 2013-12-15
上傳用戶：fanboynet
This white paper raises some fundamental issues the design engineer should address before deciding upon a communication approach for a wireless network. As no universal wireless network solution exists, it should be custom tailored to suit the application demands. Defining your application communication characteristics is the key to ensure optimal communication reliability and resistance to interfering noise sources.
標簽： 無線通信網(wǎng)絡 基本概念
上傳時間： 2013-11-23
上傳用戶：zhichenglu
Safety GuidelinesThis manual contains notices which you should observe to ensure your own personal safety, as well as toprotect the product and connected equipment. These notices are highlighted in the manual by a warningtriangle and are marked as follows according to the level of danger:
標簽： Programmable 300 and
上傳時間： 2013-12-12
上傳用戶：fandeshun
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