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.
上傳時間： 2013-10-23
上傳用戶：copu
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.
上傳時間： 2013-11-19
上傳用戶：qiaoyue
TKS仿真器B系列快速入門
上傳時間： 2013-10-31
上傳用戶：aix008
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).
上傳時間： 2013-10-10
上傳用戶：geshaowei
電子發燒友網：本資料是關于單片機及接口技術這門課程的期末考試試卷及答案的詳解。 8.當需要從MCS-51單片機程序存儲器取數據時，采用的指令為( )。 a)MOV A, @R1 b)MOVC A, @A + DPTR c)MOVX A, @ R0 d)MOVX A, @ DPTR 二、填空題(每空1分，共30分) 1.一個完整的微機系統由 和 兩大部分組成。 2.8051 的引腳RST是____(IN腳還是OUT腳)，當其端出現____電平時,8051進入復位狀態。8051一直維持這個值，直到RST腳收到____電平，8051才脫離復位狀態，進入程序運行狀態，從ROM H單元開始取指令并翻譯和執行。 3.半導體存儲器分成兩大類 和 ，其中 具有易失性，常用于存儲 。
上傳時間： 2015-01-03
上傳用戶：wfl_yy
一個簡單好用的B+樹算法實現
上傳時間： 2015-01-04
上傳用戶：縹緲
一個用Basic實現的B-Tree算法
上傳時間： 2013-12-30
上傳用戶：ccclll
一個用Java applet實現的B-Tree算法
上傳時間： 2013-12-25
上傳用戶：qiao8960
用C++實現的B-Tree算法
上傳時間： 2014-01-20
上傳用戶：jiahao131
用Borland C寫的B-Tree算法
上傳時間： 2014-12-05
上傳用戶：xzt
