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.
上传时间： 2013-10-23
上传用户：copu
Award BIOS(Basic Input/Output System)(电脑启动时所必需)的源码
上传时间： 2014-01-04
上传用户：ecooo
Displaying Multiple Views in IE
标签： Displaying Multiple Views IE
上传时间： 2013-12-07
上传用户：努力努力再努力
很过瘾的虚拟肯德基买卖模拟机,上学期JAVA课的PROJECT,可以设定出售和生产的比例,体现后台的multiple thread
标签： multiple PROJECT thread JAVA
上传时间： 2015-03-20
上传用户：小草123
A very small 250-line library (written entirely in MATLAB) that allows multiple MATLAB programs to talk to each other, so that hundreds of processors can work together.
标签： MATLAB entirely multiple programs
上传时间： 2015-04-03
上传用户：nanshan
This module can be used to interface to the MMC card in MMC or * SPI modes. It supports a multiple card environment. The reset and * identification processes assume multiple cards on the bus. * In MMC mode, the card number is used as the RCA operand in the * commands.
标签： MMC interface multiple supports
上传时间： 2014-01-07
上传用户：qilin
Multiple Outputs 神经网络算发演示2
上传时间： 2015-05-16
上传用户：xg262122
讲述了Java Input/Output库的主要包和类。有关Channel类和ByteBuffer类特别适用于对文件操作中的某些特殊要求。
标签： ByteBuffer Channel Output Input
上传时间： 2013-12-14
上传用户：GHF
The Valgrind distribution has multiple tools. The most popular is the memory checking tool (called Memcheck) which can detect many common memory errors such as: * touching memory you shouldn t (eg. overrunning heap block boundaries) * using values before they have been initialized * incorrect freeing of memory, such as double-freeing heap blocks * memory leaks.
标签： distribution The Valgrind checking
上传时间： 2014-01-14
上传用户：xc216
realize overlapped-add method ％[y]=overlpadd(x,h,Nfft) ％y:output sequence ％x:input sequence ％h:filter impulse response sequence ％Nfft:points of each DFT operation ％重叠相加法实现分段卷积
标签： sequence overlapped-add overlpadd realize
上传时间： 2015-07-22
上传用户：as275944189
