The PCA9555 is a 24-pin CMOS device that provides 16 bits of General Purpose parallelInput/Output (GPIO) expansion for I2C-bus/SMBus applications and was developed toenhance the NXP Semiconductors family of I2C-bus I/O expanders. The improvementsinclude higher drive capability, 5 V I/O tolerance, lower supply current, individual I/Oconfiguration, and smaller packaging. I/O expanders provide a simple solution whenadditional I/O is needed for ACPI power switches, sensors, push buttons, LEDs, fans, etc.The PCA9555 consists of two 8-bit Configuration (Input or Output selection); Input, Outputand Polarity Inversion (active HIGH or active LOW operation) registers. The systemmaster can enable the I/Os as either inputs or outputs by writing to the I/O configurationbits. The data for each Input or Output is kept in the corresponding Input or Outputregister. The polarity of the read register can be inverted with the Polarity Inversionregister. All registers can be read by the system master. Although pin-to-pin and I2C-busaddress compatible with the PCF8575, software changes are required due to theenhancements, and are discussed in Application Note AN469.
上传时间： 2013-11-13
上传用户：fredguo
The PCA9557 is a silicon CMOS circuit which provides parallel input/output expansion for SMBus and I2C-bus applications. The PCA9557 consists of an 8-bit input port register, 8-bit output port register, and an I2C-bus/SMBus interface. It has low current consumption and a high-impedance open-drain output pin, IO0. The system master can enable the PCA9557’s I/O as either input or output by writing to the configuration register. The system master can also invert the PCA9557 inputs by writing to the active HIGH polarity inversion register. Finally, the system master can reset the PCA9557 in the event of a time-out by asserting a LOW in the reset input. The power-on reset puts the registers in their default state and initializes the I2C-bus/SMBus state machine. The RESET pin causes the same reset/initialization to occur without de-powering the part.
上传时间： 2014-01-18
上传用户：bs2005
The CAT9555 is a CMOS device that provides 16-bitparallel input/output port expansion for I²C and SMBuscompatible applications. These I/O expanders providea simple solution in applications where additional I/Osare needed: sensors, power switches, LEDs,pushbuttons, and fans.
上传时间： 2014-01-09
上传用户：1101055045
The CAT9534 is an 8-bit parallel input/output portexpander for I²C and SMBus compatible applications.These I/O expanders provide a simple solution inapplications where additional I/Os are needed: sensors,power switches, LEDs, pushbuttons, and fans.The CAT9534 consists of an input port register, anoutput port register, a configuration register, a polarityinversion register and an I²C/SMBus-compatible serialinterface.
上传时间： 2013-11-09
上传用户：liulinshan2010
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
Abstract: This application note explains the hardware of different types of 1-Wire® interfaces and software examples adapted to this hardware with a focus on serial ports. Depending on the types of iButtons required for a project and the type of computer to be used, the most economical interface is easily found. The hardware examples shown are basically two different types: 5V general interface and 12V RS-232 interface. Within the 5V group a common printed circuit board could be used for all circuits described. The variations can be achieved by different populations of components. The same principal is used for the 12V RS-232 interface. The population determines if it is a Read all or a Read/Write all type of interface. There are other possible circuit implementations to create a 1-Wire interface. The circuits described in this application note cover many different configurations. For a custom application, one of the described options can be adapted to meet individual needs.
标签： iButtons Reading Writing and
上传时间： 2013-10-29
上传用户：long14578
基于多点网络的水厂自动监控系统设计Design of MPI Based Automatic Monitoring and Control System in Water Works刘 美 俊(湖南工程学院，湘潭411101)摘要针对水厂工作水泵多、现场离控制站距离远的特点，提出了一种基于MPI多点网络的自动监控系统的设计方法，分析了系统的工作原理，介绍了系统中数据的采集与处理、主站与从站的通信原理以及系统软件的设计。由于这种系统的主、从站PLC之间采用MPI网络通信，具有运行可靠、性能价格比高的特点，所以适用于中小规模水厂的分布式监控场合。关键词多点网络主站从站监控系统Abstract Ina ccordancew ithth efe atuersof w aterw orks,i. e. ，manyp umpsin o perationa ndth ep umps， farfor mt hec ontrolst ation,th em ethodo fdesigninga na utomati(〕monitoringa ndc ontorlsy stemb asedo nM PIis p resented.Th eo perationalpr incipleo fth esy stemi san alyzed,th ed atac olection,data processing; communication between master station and slave station as wel as design and system software are discussed. Because MPI network communicationis used among master station, slave stations and PLC, the system is reliable and high cost-efective. It is， suitable for smal and mediumsized water works for distrbuted monitoring and control.Keywords MPI Masterst ation Slaves tation Monitoringa ndc ontorlsy stem 自来 水 厂 的自动控制系统一般分为两大部分，一对组态硬件要求较高，投资较大。相对而言，MPI网是水源地深水泵的工作控制，一是水厂区变频恒压供络速度可达187.5 M bps，通过一级中继器传输距离可水控制，两部分的实际距离通常都比较远。某厂水源达Ikm 。根据水厂的具体情况，确定以MPI方式组地有3台深井泵给水厂区的蓄水池供水。水厂区的成网络，主站PLC为S7-300系列的CPU3121FM，从任务是对水池的水进行消毒处理后，通过加压泵向管站为S7-200系列的CPU222。这样既满足了系统要路恒压供水。选用Siemens公司的S7系列可编程控求，又相对于Profibus网络节省了三分之一的成本，制器(PLC)和上位机组成实时数据采集和监控系统， 这种分布式监控系统具有较高的性能价格比。系统对深水泵进行远程控制，对供水泵采用变频器进行恒中PLC的物理层采用RS - 485接口，网络延伸选用压控制以保证整个水厂的电机设备安全、可靠地运带防雷保护的中继器，使系统的安全运行得到了保行。证。MPI网络的拓扑结构如图1所示。1 多点网络(NWI)监控系统的组成Sie me ns 公司S7系列PLC通常有MP」多点网络与Profibus现场总线网络两种组网方式。Profibus现场总线的应用目前较为普遍，通用性较好，它由Profibus一DP, Profibus一FMS, Profibus一PA组成。Profibus - DP型用于分散外设间的数据传输，传输速率为9.6kbps一12Mbps，主要用于现场控制器与分散1/0之间的通信，可满足交直流调速系统快速响应的时间要求，特别适合于加工自动化领域的应用;Profibus - FMS主要解决车间级通信问题，完成中等传输速度的循环或非循环数据交换任务，适用于纺织、楼宇自动化、可编程控制器、低压开关等;Profibus - PA型采用了OSI模型的物理层和数据链路层，适用于过程自动化的总线类型。
上传时间： 2013-10-09
上传用户：fac1003
pwm research and implementation on mcs-51
标签： implementatio research pwm and
上传时间： 2013-11-23
上传用户：a155166
The Linux Programming Interface - A Linux and UNIX System
标签： Programming Linux Interface Handbook
上传时间： 2013-11-10
上传用户：asdstation
The main objective of this book is to present all the relevant informationrequired for RF and micro-wave power amplifier design includingwell-known and novel theoretical approaches and practical design techniquesas well as to suggest optimum design approaches effectively combininganalytical calculations and computer-aided design. This bookcan also be very useful for lecturing to promote the analytical way ofthinking with practical verification by making a bridge between theoryand practice of RF and microwave engineering. As it often happens, anew result is the well-forgotten old one. Therefore, the demonstrationof not only new results based on new technologies or circuit schematicsis given, but some sufficiently old ideas or approaches are also introduced,that could be very useful in modern practice or could contributeto appearance of new ideas or schematic techniques.
标签： Amplifier Microwave Design Power
上传时间： 2013-12-22
上传用户：vodssv
