虫虫首页| 资源下载| 资源专辑| 精品软件
登录| 注册

a<b>DM</b>in

  • Input Signal Rise and Fall Tim

    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.For input signals, which do not provide the required rise/fall times, external circuitry mustbe used to shape the signal transitions.In the attached diagram, the effect of the sample rate is shown. The numbers 1 to 5 in thediagram represent possible sample points. Waveform a) shows the result if the inputsignal transition time through the undefined TTL-level area is less than the time distancebetween the sample points (sampling at 1, 2, 3, and 4). Waveform b) can be the result ifthe sampling is performed more than once within the undefined area (sampling at 1, 2, 5,3, and 4).Sample points:1. Evaluation of the signal clearly results in a low level2. Either a low or a high level can be sampled here. If low is sampled, no transition willbe detected. If the sample results in a high level, a transition is detected, and anappropriate action (e.g. capture) might take place.3. Evaluation here clearly results in a high level. If the previous sample 2) had alreadydetected a high, there is no change. If the previous sample 2) showed a low, atransition from low to high is detected now.

    标签: Signal Input Fall Rise

    上传时间: 2013-10-23

    上传用户:copu

  • MPC7400l零件号码规范说明

    This document describes part number speciÞc changes to recommended operating conditions and revised electrical speciÞcations,as applicable, from those described in the generalMPC7400 Hardware SpeciÞcations.SpeciÞcations provided in this Part Number SpeciÞcation supersede those in theMPC7400 Hardware SpeciÞcationsdated 9/99(order #: MPC7400EC/D) for these part numbers only; speciÞcations not addressed herein are unchanged. This document isfrequently updated, refer to the website at http://www.mot.com/SPS/PowerPC/ for the latest version.Note that headings and table numbers in this data sheet are not consecutively numbered. They are intended to correspond to theheading or table affected in the general hardware speciÞcation.Part numbers addressed in this document are listed in Table A. For more detailed ordering information see Table B.

    标签: 7400l 7400 MPC 零件

    上传时间: 2013-11-19

    上传用户:qiaoyue

  • TKS仿真器B系列快速入门

    TKS仿真器B系列快速入门

    标签: TKS 仿真器 快速入门

    上传时间: 2013-10-31

    上传用户:aix008

  • RT9018,RT9018AB-05 datasheet pdf

    The RT9018A/B is a high performance positive voltage regulator designed for use in applications requining very low Input voltage and very low dropout voltage at up to 3A(peak).

    标签: 9018 datasheet RT

    上传时间: 2013-10-10

    上传用户:geshaowei

  • 单片机及接口技术考试试卷及答案详解

      电子发烧友网:本资料是关于单片机及接口技术这门课程的期末考试试卷及答案的详解。          8.当需要从MCS-51单片机程序存储器取数据时,采用的指令为( )。   a)MOV A, @R1 b)MOVC A, @A + DPTR   c)MOVX A, @ R0 d)MOVX A, @ DPTR   二、填空题(每空1分,共30分)   1.一个完整的微机系统由 和 两大部分组成。   2.8051 的引脚RST是____(IN脚还是OUT脚),当其端出现____电平时,8051进入复位状态。8051一直维持这个值,直到RST脚收到____电平,8051才脱离复位状态,进入程序运行状态,从ROM H单元开始取指令并翻译和执行。   3.半导体存储器分成两大类 和 ,其中 具有易失性,常用于存储 。

    标签: 单片机 接口技术 试卷

    上传时间: 2015-01-03

    上传用户:wfl_yy

  • 一个简单好用的B+树算法实现

    一个简单好用的B+树算法实现

    标签: 算法

    上传时间: 2015-01-04

    上传用户:缥缈

  • 一个用Basic实现的B-Tree算法

    一个用Basic实现的B-Tree算法

    标签: B-Tree Basic 算法

    上传时间: 2013-12-30

    上传用户:ccclll

  • 一个用Java applet实现的B-Tree算法

    一个用Java applet实现的B-Tree算法

    标签: B-Tree applet Java 算法

    上传时间: 2013-12-25

    上传用户:qiao8960

  • 用C++实现的B-Tree算法

    用C++实现的B-Tree算法

    标签: B-Tree 算法

    上传时间: 2014-01-20

    上传用户:jiahao131

  • 用Borland C写的B-Tree算法

    用Borland C写的B-Tree算法

    标签: Borland B-Tree 算法

    上传时间: 2014-12-05

    上传用户:xzt