針對船舶氣象儀保障維修而設(shè)計的船舶氣象儀測試系統(tǒng)，包括信息處理終端、主儀器檢測模塊、傳感器檢測模塊，各個模塊都采用基于AVR單片機的嵌入式系統(tǒng)，模塊之間通過CAN總線進行通信。結(jié)果表明，船舶氣象儀測試系統(tǒng)能夠快速檢測船舶氣象儀故障，與單純依靠人工方式排查故障相比，故障檢測時間縮短了60%以上。
Abstract:
The test system of ship meteorological instrument was developed to satisfy the maintenance of ship meteorological instruments，which composed of information processing terminal， testing module of main instrument and testing module of sensors. Each of these modules included an embedded system based on microcontroller of AVR series and communicated with other module by CAN bus. The results show that the test system can judge the fault of ship meteorological instrument quickly and shorten the fault detection time as much as 60% compared with simple manual troubleshooting.
RT0S在MCS-51系列單片機中的應(yīng)用:在嵌入式應(yīng)用中使用實時操作系統(tǒng)(RTOS)，已成為單片機應(yīng)用領(lǐng)域的一個熱點．本文對RTOS內(nèi)核做了簡單的介紹．討論了在KEIL C V6．23編譯器中，移植實時系統(tǒng)u c／os-iI到51系列單片機的一些關(guān)鍵問題．
All inputs of the C16x family have Schmitt-Trigger input characteristics. These Schmitt-Triggers are intended to always provide proper internal low and high levels, even if anundefined voltage level (between TTL-VIL and TTL-VIH) is externally applied to the pin.The hysteresis of these inputs, however, is very small, and can not be properly used in anapplication to suppress signal noise, and to shape slow rising/falling input transitions.Thus, it must be taken care that rising/falling input signals pass the undefined area of theTTL-specification between VIL and VIH with a sufficient rise/fall time, as generally usualand specified for TTL components (e.g. 74LS series: gates 1V/us, clock inputs 20V/us).The effect of the implemented Schmitt-Trigger is that even if the input signal remains inthe undefined area, well defined low/high levels are generated internally. Note that allinput signals are evaluated at specific sample points (depending on the input and theperipheral function connected to it), at that signal transitions are detected if twoconsecutive samples show different levels. Thus, only the current level of an input signalat these sample points is relevant, that means, the necessary rise/fall times of the inputsignal is only dependant on the sample rate, that is the distance in time between twoconsecutive evaluation time points. If an input signal, for instance, is sampled throughsoftware every 10us, it is irrelevant, which input level would be seen between thesamples. Thus, it would be allowable for the signal to take 10us to pass through theundefined area. Due to the sample rate of 10us, it is assured that only one sample canoccur while the signal is within the undefined area, and no incorrect transition will bedetected. For inputs which are connected to a peripheral function, e.g. capture inputs, thesample rate is determined by the clock cycle of the peripheral unit. In the case of theCAPCOM unit this means a sample rate of 400ns @ 20MHz CPU clock. This requiresinput signals to pass through the undefined area within these 400ns in order to avoidmultiple capture events.
用單片機配置FPGA—PLD設(shè)計技巧
Configuration/Program Method for Altera Device
Configure the FLEX Device
You can use any Micro-Controller to configure the FLEX device–the main idea is clocking in ONE BITof configuration data per CLOCK–start from the BIT 0The total Configuration time–e.g. 10K10 need 15K byte configuration file•calculation equation–10K10* 1.5= 15Kbyte–configuration time for the file itself•15*1024*8*clock = 122,880Clock•assume the CLOCK is 4MHz•122,880*1/4Mhz=30.72msec
This application note shows how to achieve low-cost, efficient serial configuration for Spartan FPGA designs. The approachrecommended here takes advantage of unused resources in a design, thereby reducing the cost, part count, memory size,and board space associated with the serial configuration circuitry. As a result, neither processor nor PROM needs to be fullydedicated to performing Spartan configuration.In particular, information is provided on how the idle processing time of an on-board controller can be used to loadconfiguration data from an off-board source. As a result, it is possible to upgrade a Spartan design in the field by sending thebitstream over a network.
在車載自組網(wǎng)中，路由協(xié)議很大程度上決定了整個網(wǎng)絡(luò)的性能。如何有效的利用車流信息提高傳輸質(zhì)量是改善路由性能的一個關(guān)鍵問題。本文基于速度-密度線性模型，提出了一種實時車流密度的路由協(xié)議RVDR（Real-time Vehicle Density Routing）。該協(xié)議通過與鄰居節(jié)點交換的速度信息，對相關(guān)道路車流密度進行預測，并給出基于車流密度信息的路徑選擇方法。仿真結(jié)果表明，與現(xiàn)有協(xié)議相比，RVDR協(xié)議在實時性和高效性等性能方面得到改進。
