1-Wire软件资源指南和驱动程序说明

性能优异的1-Wire网络驱动器摘要：本文介绍了一种基于微控制器的1-Wire®主机接口，适用于小规模、中等规模以及大规模的1-Wire网络。

采用精细的阻抗匹配和"智能" (软件控制)强上拉、摆率控制等方法保证网络的可靠工作。

本文给出了软件流程图，有助于用户利用任何适当的微控制器产生正确的复位脉冲、在线检测、写“1”、写“0”以及读时隙的1-Wire时序。

示波器测试曲线说明了驱动器的时间特性以及远距离通信时传输线的影响。

简介1-Wire网络的可靠性在很大程度上取决于主机与1-Wire从机器件之间所采用的通信驱动电路的性能。

本文介绍了一种1-Wire主机端接口，采用精细的阻抗匹配和"智能" (软件控制)强上拉等方法，保证网络在轻载到重载范围内均能可靠工作，且通信距离可达500m。

关于创建可靠的1-Wire网络指南，请参见应用笔记148。

电路描述网络驱动器(图1)由下拉部分(Q1，R1，C1，R5)和上拉部分(Q2，R2，C2，R6)组成。

晶体管Q3与周围的元件(C4、R7)组成强上拉电路，可为诸如EEPROM、温度传感器等器件提供额外电源。

本文没有讨论"强上拉"的功能。

任何时候，三个晶体管中最多只有一个处于导通状态；当1-Wire不进行通信("空闲"状态)时，这三个晶体管都不导通。

图1. 驱动器原理图R4、R1和R3的串联电路提供标准的1-Wire到V CC上拉。

在这种电路情况下，总的上拉电阻近似为1kΩ。

当1-Wire线空闲时，则线上呈现此阻抗。

由于R4与Q1的漏极相连，因此Q1导通时电流会流过该电阻，但不会影响1-Wire总线的低电平电压。

1-Wire总线电压升至5V的速度是由R4+R1+R3的电阻值和1-Wire网络的负载决定的。

不建议减小R4阻值，否则会导致1-Wire总线的低电平电压升高，而这不是我们所期望的。

单总线它实现了在一条数据线上进行双向数据传输使系统布线更方便图８．６．２　程序８５１５ｄｅｆ．ｄａｔ定义度定义汉字的显示字符　Ｄｅｆｌｃｄｃｈａｒ　２　，　３１　，　４　，　３１　，　４　，　１２　，　１０　，　１８　，　１７ 天Ｐｏｒｔｃ．０接ＤＳ１８２０的数据线　Ｃｏｎｆｉｇ　Ｌｃｄｐｉｎ＝Ｐｉｎ，Ｄｂ４＝Ｐｏｒｔａ．４，Ｄｂ５＝Ｐｏｒｔａ．５，Ｄｂ６＝Ｐｏｒｔａ．６，Ｄｂ７＝Ｐｏｒｔａ．７，Ｅ＝Ｐｏｒｔａ．０，Ｒｓ＝Ｐｏｒｔａ．１　Ｃｏｎｆｉｇ　Ｌｃｄ　＝　１６　＊　２ 清ＬＣＤ显示第一行显示提示字符串　Ｌｏｃａｔｅ　２　，　１　：　Ｌｃｄ　Ｃｈｒ（１）　；　Ｃｈｒ（２） ２列显示汉字　Ｌｏｃａｔｅ　２　，　８　：　Ｌｃｄ　Ｃｈｒ（０）　；　＂Ｃ＂ Ｄｏ　 １ｗｗｒｉｔｅ　＆ＨＣＣ　：　１ｗｗｒｉｔｅ　＆Ｈ４４ 启动温度转换　 Ｗａｉｔｍｓ　２５５　 Ｗａｉｔｍｓ　２５５ ＤＳ１８２０初始化　 １ｗｗｒｉｔｅ　＆ＨＣＣ 跳过ＲＯＭ操作　 １ｗｗｒｉｔｅ　＆ＨＢＥ 读温度值　 Ｄａｔａ１（１）　＝　１ｗｒｅａｄ（９） 共９个字节　 １ｗｒｅｓｅｔ 无ＤＳ１８２０显示　 Ｅｌｓｅ　 Ｃｒｃ　＝　０　 Ｆｏｒ　Ｉ　＝　１　Ｔｏ　９ ＣＲＣ校验正确ＣＲＣ校验正确负温度显示号　 Ｅｌｓｅ　 Ｌｏｃａｔｅ　２　，　３　：　Ｌｃｄ　＂　＂ 以下显示温度ＣＲＣ校验错＊＊＊．＊ＣＲＣ计算用的表格　Ｄａｔａ　０　，　９４　，　１８８　，　２２６　，　９７　，　６３　，　２２１　，　１３１　，　１９４　，　１５６　Ｄａｔａ　１２６　，　３２　，　１６３　，　２５３　，　３１　，　６５　，　１５７　，　１９５　，　３３　，　１２７　Ｄａｔａ　２５２　，　１６２　，　６４　，　３０　，　９５　，　１　，　２２７　，　１８９　，　６２　，　９６　Ｄａｔａ　１３０　，　２２０　，　３５　，　１２５　，　１５９　，　１９３　，　６６　，　２８　，　２５４　，　１６０　是各种总线中使用信号线较少多主机时钟同步和仲裁等功能很强的总线许多接口芯片如ＬＣＤ驱动Ａ／Ｄ，Ｄ／Ａ都采用Ｉ２Ｃ接口而且大多数的ＩＣ卡的接口都采用Ｉ２Ｃ总线用ＡＶＲ系统构成简易ＩＣ卡读写器Ｉ２Ｃ串行总线使用两根信号线另一根是时钟线ＳＣＬ各设备的时钟线ＳＣＬ接到总线的ＳＣＬ关于Ｉ２Ｃ的详细内容请参考有关的书籍和资料因此需要用两根　Ｉ／Ｏ线来模拟实现Ｉ２Ｃ总线的功能实现Ｉ２Ｃ总线启始读ＢＡＳＣＯＭ－ＡＶＲ提供了专用的　Ｉ２Ｃ语句实验中采用的ＩＣ卡为ＡＴＭＥＬ公司的ＡＴ２４Ｃ０１Ａ／２／４／８／１６该类ＩＣ卡上的芯片就是采用Ｉ２Ｃ总线接口的串行ＣＭＯＳ　ＥＥＰＲＯＭＡＶＲ系列的单片微控制器内部还提供了一定容量的ＥＥＰＲＯＭ设定值或密码口令字等它不仅可使系统设计节省硬件（ＥＥＰＲＯＭ芯片）和连线提高了系统的可靠性和保密性使用了ＡＶＲ片内的ＥＥＰＲＯＭ来保存密码判别ＩＣ卡的非法性写用户使用ＰＣ的键盘输入８位自定密码将密码写入用户的ＩＣ卡中（也可同时写入ＡＶＲ的ＥＥＰＲＯＭ中作为系统密码）并同系统密码核对ＩＣ卡读写器采用ＬＣＤ液晶显示器　原理图Ｅｘｐ９．ｂａｓ　￥ｒｅｇｆｉｌｅ　＝　＂８５１５ｄｅｆ．ｄａｔ＂　￥ｃｒｙｓｔａｌ　＝　４００００００　￥ｂａｕｄ　＝　９６００　Ｄｉｍ　Ｉ　Ａｓ　Ｂｙｔｅ　，　Ｔｅｍｐ　Ａｓ　Ｂｙｔｅ　定义ＬＣＤ显示屏接口　Ｃｏｎｆｉｇ　Ｓｃｌ　＝　Ｐｏｒｔｄ．７ 定义Ｐｏｒｔｄ．６为Ｉ２Ｃ总线的Ｄｄａ　Ｃｏｎｓｔ　Ａｄｒｅｓｗ　＝　＆ＨＡ０ 定义ＩＣ卡的读地址指令字　Ｃｏｎｆｉｇ　Ｐｉｎｃ．０　＝　Ｉｎｐｕｔ　，　Ｐｉｎｃ．１　＝　Ｉｎｐｕｔ　，　Ｐｉｎｃ．２　＝　Ｉｎｐｕｔ　Ｐｏｒｔｃ．０　＝　１　：　Ｐｏｒｔｃ．１　＝　１　：　Ｐｏｒｔｃ．２　＝　１ 清ＬＣＤ显示　Ｄｏ　 Ｃｌｓ　 Ｌｏｃａｔｅ　１　，　１　：　Ｌｃｄ　＂Ｄｅｍｏ　ｆｏｒ　ＩＣ＿Ｃａｒｄ＂ 检测有无ＩＣ卡插入　 Ｌｏｃａｔｅ　２　，　１　：　Ｌｃｄ　＂Ｎｏ　ＩＣ＿Ｃａｒｄ ＂　有ＩＣ卡插入　 Ｉｆ　Ｐｉｎｃ．０　＝　０　Ｔｈｅｎ Ｃｌｓ　 Ｌｏｃａｔｅ　１　，　１　：　Ｌｃｄ　＂Ｅｎｔｅｒ　Ｐａｓｓｗｏｒｄ：　＂　要求输入密码字 Ｉ　＝　１　 Ｌｏｃａｔｅ　２　，　１　 Ｄｏ　 Ｔｅｍｐ　＝　Ｉｎｋｅｙ（） 的密码字符长度为８个　 Ｌｃｄ　Ｃｈｒ（ｔｅｍｐ） 将８个密码字写入ＩＣ卡中　 Ｉ２ｃｓｔａｒｔ 如果系统设置为修改系统密码时 Ｗｒｉｔｅｅｅｐｒｏｍ　Ｄａｔａ１（ｉ）　，　Ｉ 写入地址为１－８　 Ｅｎｄ　Ｉｆ　 Ｆｏｒ　Ｉ　＝　１　Ｔｏ　８ 判别写入密码同用户输入的密码 Ｉｆ　Ｄａｔａ１（ｉ）　＜＞　Ｄａｔａ２（ｉ）　Ｔｈｅｎ 相同不同等待用户抽出ＩＣ卡　 Ｅｌｓｅ 读ＩＣ卡上的密码字８个 Ｌｃｄ　Ｃｈｒ（ｄａｔａ１（ｉ）） 读系统密码字８个　 Ｎｅｘｔ　 Ｃａｒｄ＿ｏｋ　＝　０　 Ｆｏｒ　Ｉ　＝　１　Ｔｏ　８ 比较　 Ｃａｒｄ＿ｏｋ　＝　１　 Ｅｘｉｔ　Ｆｏｒ　 Ｅｎｄ　Ｉｆ　 Ｎｅｘｔ　 Ｌｏｃａｔｅ　２　，　１　 Ｉｆ　Ｃａｒｄ＿ｏｋ　＝　１　Ｔｈｅｎ　 Ｌｃｄ　＂Ｐａｓｓｗｏｒｄ　ｎｏｔ　ｏｋ！＂ 密码相符　 Ｅｎｄ　Ｉｆ　 Ｄｏ　 Ｌｏｏｐ　Ｕｎｔｉｌ　Ｐｉｎｃ．２　＝　１ 返回循环　Ｅｎｄ　。

Maxim > App Notes > 1-Wire® DEVICES MICROCONTROLLERSJul 08, 2008 Keywords: 1-Wire, OneWire, iButton, API, application program interface, software, examples, TMEX, java, OWAPI, publicdomain, PD, windows COM, OWCOM, , .NET, dotnetAPPLICATION NOTE 1551-Wire® Software Resource Guide Device DescriptionAbstract: There are over 30 different 1-Wire devices, including iButton® devices, that Maxim currently produces. Navigating the available APIs, software examples, and other resources to communicate with this array of devices or finding the correct resource for a single device type can be a daunting task. This document provides an overview of the available resources and a selection guide. The current 1-Wire devices are also presented in a convenient table, providing device descriptions and family code lookup.Available APIs include TMEX (an API for Microsoft Windows®), 1-Wire Public Domain Kit (a cross-platform API), the 1-Wire API for Java™ (OWAPI) and its variant 1-Wire API for .NET (), and 1-Wire API for .NET Compact (. Compact). All of the APIs described in this document are free to use without restriction and, in most cases, include the complete source code.IntroductionThere are over 30 different 1-Wire devices, including iButton devices, that Maxim currently produces. Navigating the available application program interfaces (APIs), software examples, and other resources to communicate with this array of devices, or finding the correct resource for a single device type, can be a daunting task. This guide provides an overview of available resources and a selection guide. The APIs described in this document are free to use without restriction and, in most cases, include the complete source code.1-Wire OverviewThe 1-Wire bus is a simple signaling scheme that performs two-way communications between a single master and peripheral devices over a single connection. A powerful feature that all 1-Wire bus devices share is that each and every device, in a chip or an iButton, has a factory-programmed registration number that will never be repeated in any other device. In effect, every device is unique. This allows any single device to be individually selected from among the many that can be connected to the same bus wire. Because one, two, or even dozens of 1-Wire devices can share a single wire for communications, a binary searching algorithm is used to find each device in turn. Once each device registration number is known, any device can be uniquely selected for communication using that registration number to address it.The first part of any communication involves the bus master issuing a reset, which synchronizes the entire bus. A slave device is then selected for subsequent communications. This can be done by selecting all slaves, selecting a specific slave (using the registration number of the device), or by discovering the next slave on the bus using a binary search algorithm. These commands are referred to collectively as network function or read-only-memory (ROM) commands. Once a specific device has been selected, all other devices drop out and ignore subsequent communications until the next reset is issued.Once a device is isolated for bus communication, the master can issue device-specific commands to it, send data to it, or read data from it. Because each device type performs different functions and serves a different purpose, each type has a unique protocol once it has been selected. Even though each device type may have different protocols and features, they all have the same selection process and follow the command flow seen in Figure 1.Figure 1. Typical 1-Wire communication flow.An integral part of the unique registration number in each slave is an 8-bit family code. This code is specific to the device model. Because each device model performs different functions, this code is used to select the protocol that will be used to control or interrogate it. See Table 1 for a mapping of family codes for Maxim 1-Wire parts.Information Business Unit's (BU's) software libraries.¹These devices are no longer recommended for new designs.API FundamentalsThe different APIs for communicating with 1-Wire devices have common features that reflect the fundamental communication issues arising from the protocol. Figure 2 outlines the common groupings of the functions for the different APIs. Sincemost 1-Wire devices have memory, the memory I/O functions are treated as a common API group although the functions donot apply to all devices. All other nonmemory specialty functions are lumped into the device-specific device grouping.The typical sequence to use these functions is outlined in Figure 3. The SESSION functions wrap around the communication calls to the device, which typically involve using a NETWORK function followed by a memory or DEVICE-specific operation.Figure 3. API usage flow.The nature of iButton communication is inherently 'touch.' This means that contact with the device is not always reliable. The iButton might be inserted into the reader and have intermittent contact during the read. Consequently a consistent methodology of error recovery must be rigorously followed. This usually entails doing retries when a spurious error is detected and utilizing CRC checks in data communication. The file I/O functions in the APIs use a standard file structure detailed inthe 1-Wire File Structure section of application note 114, "1-Wire File Structure." This structure uses a CRC16 on every page of data to quickly verify the validity of the data being read. Most of the 1-Wire API functions have little or no automatic retries. The retries are under application control. See the application note 159, "Ultra-Reliable 1-Wire Communications," for methodology of error recovery and risk assessment in doing 1-Wire communication.API SelectionThere are principally five different APIs that are considered in this document. The APIs operate on different platforms, use different languages, and have different capabilities. Table 2 displays these five APIs with a brief description, and Table 3 maps the operating system with the available APIs divided by language.Table 2. API Descriptions1-Wire Public Domain PD A completely open-source public domain API written in C and designed to be portable across multiple PC operating systems, handheld operating systems, and microcontroller platforms. For PC platforms, it supports all 1-Wire adapters (masters) through native driver libraries on Microsoft Windows and specific 1-Wire adapters (DS9097U serial and DS9490 USB adapters) on other PC operating systems using cross-platform libraries.1-Wire API for Java OWAPI Completely open-source, high-level Java API that supports almost ALL 1-Wire devices. In addition to native 1-Wire master support, it also supports theDS9097U serial adapter and DS9490 USB adapter through cross-platform libraries.1-Wire API for .NET OWAPI code base compiled with J# for the Microsoft .NET Framework.1-Wire API for .NET Compact pact Compact .NET Framework for Windows CE machines or platforms that do not have the Microsoft Visual J#® Redistributable Package. It currently consists of just the low-level 1-Wire link and Network layer ported to C#.TMEX API TMEX Supports all 1-Wire master adapters on Windows platforms (32 and 64 bit). Provides link and file I/O functions, but no device functions. Drivers are closed source. This API is called by other APIs to obtain access to all ofthe 1-Wire adapter types.Table 3. API Operating System and Language CoverageWindows Vista®TMEX //pact PD OWAPI Windows Vista x64TMEX //pact PD OWAPI*TINI® is an embedded platform with a Java-based OS made by Maxim.¹No longer supported. Legacy driver downloads still available from the Maxim web site.The support of the individual device families also varies from API to API. Table 4 lists all of the currently available 1-Wire devices with flags indicating the available support in each API. The key for the Table 4 flags is located at the bottom. Note that the device cells without shading are considered fully supported by the API. A light-shaded cell indicates partial support, and dark-shaded cell indicates minimal support.owAttribute - Changes the attributes of a file.owChangeDirectory - Changes the current directory.owCloseFile - Closes a file.owCreateDir - Creates a directory.owCreateFile - Creates a file for writing.owCreateProgramJob - Creates a write buffer for logging EPROM programming pending jobs.owDeleteFile - Deletes a file.owDoProgramJob - Write the pending EPROM programming jobs.owFirstFile - Finds the first file in the current directory.owFormat - Formats the 1-Wire File Structure file system.owGetCurrentDir - Gets the current directory.owNextFile - Finds the next file in the current directory.owOpenFile - Opens a file for reading.owReadFile - Reads an opened file.owReadFile - Reads data from a file.owRemoveDir - Removes a directory.owReNameFile - Changes the name of a file.owWriteFile - Writes to a file that has been created.DoAtoDConversion - Does an A/D conversion on DS2450.ReadSwitch12 - Reads the state of the DS2406 switch.readCounter - Reads the counter value associated with a specific memory page on a DS2423 1-Wire chip....(too numerous to list all device-specific functions)Figure 4. PD API functions.Example 1 shows a PD code fragment that follows the API usage flow outlined in Figure 3. For simplicity, each device on the 1-Wire network is discovered during each pass through the work loop. A more sophisticated application could potentially find just one device type or perhaps select a device found in a previous search.int rslt, portnum=0, doing_work=1;char portString[50]; // set to platform appropriate port string// work loopwhile (doing_work){// acquire the 1-Wire Net (SESSION)if (owAcquire(portnum, portString)){// find all devices (NETWORK)rslt = owFirst(portnum, TRUE, FALSE);while (rslt){// do SOMETHING with device found (TRANSPORT/FILE/DEVICE)// . . .// find the next device (NETWORK)rslt = owNext(portnum, TRUE, FALSE);}// release the 1-Wire Net (SESSION)owRelease(portnum);}else{// Could not acquire 1-Wire network// . . .}// do other application work// . . .}Example 1. PD CODE example.Figures 5a and 5b list the C-language modules that make up each of the two sets of 1-Wire PD libraries. Also displayed are the 'TODO' functions that must be provided to port the library to a new platform. Several example platform link files that implement the 'TODO' functions are provided in the kit.owsesu.cowllu.c ds2480ut.c ds2480.hownetu.c crcutil.c (required to compile)mbappreg.c mbappreg.h mbee.c mbee.h mbee77.c mbee77.hmbeewp.c mbeewp.h mbeprom.c mbeprom.h mbnv.c mbnv.hmbnvcrc.c mbnvcrc.h mbscr.c mbscr.h mbscrcrc.c mbscrcrc.hmbscree.c mbscree.h mbscrex.c mbscrex.h mbscrx77.c mbscrx77.hmbsha.c mbsha.h mbshaee.c mbshaee.h owtrnu.c pw77.cpw77.h rawmem.c rawmem.howcache.c owfile.c owfile.h owpgrw.c owprgm.cad26.c ad26.h atod20.c atod26.c atod26.h cnt1d.chumutil.c humutil.h jib96.c jib96.h jib96o.c ps02.cps02.h sha18.c sha33.c shadbtvm.c shadebit.c shaib.cshaib.h swt05.c swt12.c swt12.h swt1c.c swt1c.hswt1f.c swt29.c swt29.h swt3a.c swt3a.h temp10.cthermo21.c hermo21.h time04.c time04.h weather.c weather.hioutil.c owerr.c findtype.c ownet.h screenio.c sprintf.ccrcutil.cProvided a SERIAL interface module that implements the following functions:BreakCOM* - Sends a 'BREAK' on the serial port for at least 2ms.CloseCOM - Closes the previously opened serial port. (optional for some platforms)FlushCOM* - Allows any pending write operations to complete and clear input buffer.msDelay* - Delays at least the specified number of milliseconds.msGettick - Returns an increment millisecond counter. (optional for some examples)OpenCOM - Opens the specified serial port for communication. (optional for some platforms)ReadCOM* - Reads a specified number of bytes from the serial port.SetCOMBaud - Changes the serial BAUD rate to the rate specified. (optional if needs overdrive)WriteCOM* - Writes a specified number of bytes to the serial port.* Minimum functions required for basic operation.Figure 5a. PD 'USERIAL' implementation.(see TODO)(see TODO)ownet.c crcutil.c (required to compile)Same as USERIAL implementation except 'owtrnu.c' is replaced by 'owtran.c'.Same as USERIAL implementation.Same as USERIAL implementation.Same as USERIAL implementation.Provided a LINK and SESSION interface module that implements the following functions:owAcquire - Acquires the 1-Wire net.owRelease - Releases the previously acquired 1-Wire net.owHasOverDrive - Indicates whether the adapter has overdrive capability.owHasPowerDelivery - Indicates whether the adapter can deliver power.owHasProgramPulse - Indicates whether or not EPROM programming voltage is available.owLevel - Sets the 1-Wire net line level to Normal (5V weak pullup), Power Delivery (5V strong pullup), or Program Level (12V EPROM programming level).owProgramPulse - Sends timed programming pulse for EPROM 1-Wire device writing.owReadBitPower - Reads 1 bit and then optionally supplies power.owReadByte - Receives 8 bits from the 1-Wire net by sending all 1's (0xFF).owSpeed - Sets the speed of the 1-Wire net to Normal (16kb) or Overdrive (142kb).owTouchBit* - Sends and receives 1 bit from the 1-Wire net.owTouchByte - Sends and receives 8 bits from the 1-Wire net.owTouchReset* - Resets all devices on the 1-Wire net and return result.owWriteByte - Sends 8 bits to the 1-Wire net and verifies the echo received matches.owWriteBytePower - Sends 8 bits of communication to the 1-Wire net and then supplies power.* Minimum functions required for basic operation.Figure 5b. PD 'GENERAL' implementation.InstallationThe 1-Wire PD API is a set of C modules, so there is no formal installation. As provided in the example builds, the required modules are compiled directly into the applications. This does not preclude developers from combining the modules into a loadable library such as a Windows DLL.Keep in mind that some builds require native 1-Wire adapter drivers or equivalent. As most OS platforms have built-in serial port drivers, the userial builds of the 1-Wire PD API do not need any other driver. However, for USB and parallel port 1-Wire adapter support, native or cross-platform drivers will need to be installed. References to the appropriate driver downloads are available in the documentation of the actual 1-Wire PD Kit builds available online.1-Wire API for Java (OWAPI) OverviewThe 1-Wire API for Java was designed from the ground up to be a very robust, highly object-oriented foundation forbuilding 1-Wire applications in Java. It extends the ability of programmers to develop portable, cross-platform software and shortens the time to market for their 1-Wire integrated products.The API consists of many Java classes and interfaces. One special group of Java classes in the 1-Wire API is the container (class OneWireContainer). Support for particular 1-Wire devices, including iButtons, is provided through containers. The API has over 30 different container types, representing most 1-Wire devices. Each container encapsulates and implements the functionality of an individual device.A container interacts with a 1-Wire device through a 1-Wire adapter class that represents a physical 1-Wire adapter (class DSPortAdapter). The instance of the adapter is produced from the provider class (class OneWireAccessProvider). The actualimplementations of the 1-Wire adapters vary from platform to platform, but they all have the same interface. Some platforms use native drivers, but most at least support the DS9097U-XXX serial adapters using RXTX (a cross-platform serial COM port API). This API is available from RXTX's web site.The 1-Wire API for Java Software Development Kit is available on the iButton web site. Like the 1-Wire PD Kit, the complete Java source to OWAPI is provided under a public-domain-style license.Figure 6 shows the typical object creation sequence for this API. The 'provider' creates an instance (or enumeration) of an'adapter,' which in turn can create instances of device 'containers.' Communication to the device is then performed almost exclusively through the container.Figure 6. OWAPI object creation.Figure 7 shows the common features of a container. A device that contains memory will create a memory bank instance for each memory bank. The memory is divided up into banks depending on the feature set of the bank. For example, one bank could be volatile while another is nonvolatile. Or, a bank could be general-purpose memory or it could be memory-mapped to change the functionality of the device.Figure 7. OWAPI ONEWIRECONTAINER features.Figure 8 shows the methods provided by the base OWAPI classes. The class or package is displayed in bold. Note that, because each container has high level methods to manipulate each device type, the LINK level methods in the adapter are not usually called directly.com.dalsemi.onewire.adapter.DSPortAdapterbeginExclusive - Acquires exclusive use of the 1-Wire net.endExclusive - Releases the exclusive lock on the 1-Wire net.com.dalsemi.onewire.adapter.DSPortAdaptercanBreak - Checks if a 1-Wire 'break' (long low) operation is supported by the adapter.canDeliverPower - Checks if 'strong-pullup' power delivery is supported by the adapter.canDeliverSmartPower - Checks if 'smart' power delivery is supported by the adapter. 'Smart' power delivery is the ability to sense when power consumption has reduced and automatically stop the power delivery.canFlex - Checks if flexible long-line communication timing is supported by the adapter.canHyperdrive - Checks if hyperdrive communication speed is supported by the adapter.canOverdrive - Checks if overdrive communication speed is supported by the adapter.canProgram - Checks if 12V EPROM programming voltage is supported by the adapter.dataBlock - Sends and receives a block of data to the 1-Wire net.getBit - Reads a single bit from the 1-Wire net.getBlock - Reads a block from the 1-Wire net by sending all (0xFF)s.getByte - Reads a byte from the 1-Wire net by sending all 1's (0xFF).getSpeed - Reads the current 1-Wire communication speed.putBit - Writes a bit to the 1-Wire net.putByte - Writes a byte to the 1-Wire net and verifies the echo is correct.reset - Resets all of the 1-Wire net devices.setPowerDuration - Sets the power delivery duration.setPowerNormal - Turns off the power delivery.setProgramPulseDuration - Sets the program pulse duration.setSpeed - Sets the 1-Wire communication speed.startBreak - Starts a break (low) on the 1-Wire net.startPowerDelivery - Starts the power delivery.startProgramPulse - Starts the program pulse.com.dalsemi.onewire.adapter.DSPortAdapterexcludeFamily - Excludes a family group from the search.findFirstDevice - Finds the first device on the 1-Wire net without auto container creation.findNextDevice - Finds the next device on the 1-Wire net without auto container creation.getAllDeviceContainers - Searches and finds all devices on the 1-Wire net with containers.getDeviceContainer - Gets a device container for the 'current' device found.getFirstDeviceContainer - Finds the first device and create a container for it.getNextDeviceContainer - Finds the next device and create a container for it.setNoResetSearch - Sets the 1-Wire net search to not issue a 1-Wire reset.setSearchAllDevices - Sets the 1-Wire net search to include all devices (remove alarm-only). setSearchOnlyAlarmingDevices - Sets the 1-Wire net search to only include alarming devices.targetAllFamilies - Sets the 1-Wire net search to include all devices (remove exclusions).targetFamily - Targets a particular family group in the 1-Wire net search.(also in com.dalsemi.onewire.container.*)isAlarming - Checks to see if the device is in an alarm state.isPresent - Checks to see if the device is present on the 1-Wire net.select - Selects the 1-Wire net device to ready it for a device-specific operation command.com.dalsemi.onewire.container.MemoryBankgetBankDescription - Returns a text description of the memory bank.getSize - Gets the size of the memory bank in bytes.getStartPhysicalAddress - Gets the starting physical address of the memory bank.isGeneralPurposeMemory - Checks if the memory bank is general purpose (not memory mapped).isNonVolatile - Checks if the memory bank is nonvolatile.isReadOnly - Checks if the memory bank is read-only.isReadWrite - Checks if the memory bank is read and write capable.isWriteOnce - Checks if the memory bank is write once, such as EPROM.needsPowerDelivery - Checks if this memory bank requires power delivery to write.needsProgramPulse - Checks if this memory bank requires program pulse to write.read - Reads the memory bank without interpretation (no packet structure).setWriteVerification - Sets the API to do an extra verification after writes.write - Writes the memory bank raw (no packet structure).com.dalsemi.onewire.container.PagedMemoryBankgetExtraInfoDescription - Gets a description of extra information associated with this bank.getExtraInfoLength - Gets the length in bytes of the extra information in each page.Example 2 shows a OWAPI code fragment that follows the API usage flow outlined in Figure 3. Like the PD code example in Example 1, each device on the 1-Wire network is discovered during each pass through the work loop, while a moresophisticated application could find just one device type or a previously found device.languages, such as C#, J#, and . For 1-Wire .NET examples, please refer to the appropriate software development kitWindows Platforms Supported by TMEXThe following Microsoft Windows platforms are supported by TMEX: Windows 2008, Windows 2003, Windows Vista, and Windows XP SP2. This includes both x86 (32-bit) and x64 (64-bit) operating system versions. Please note that if drivers for earlier Windows operating system versions are required, legacy versions of TMEX are available, though not actively supported, from Maxim's web site. Please download version 4.00 or below of the 1-Wire Drivers (which install the TMEX API libraries). 1-Wire Drivers installation packages can be found here: iButton: 1-Wire Drivers for Windows.Figure 9. TMEX API drivers and other API connectivity.Figure 10 lists functions provided by the TMEX API. Note that this API does not provide any nonmemory-device-specific functions.More information on the 1-Wire Drivers and OneWireViewer demo can be found on the iButton web site under "Software Resources."Other ToolsWhile the APIs discussed in this document represent a large part of the available resources for communication with 1-Wire devices, it is by no means the only resource. This section outlines some other available resources.Software Authorization APISoftware authorization is simply the locking of a software application to require the presence of a hardware token. The token in this case is an iButton connected to the user's workstation. The application polls for the presence and validity of the iButton before running. It can also continuously query while the application executes. In practice, any of the APIs outlined in this document can be used for this type of application; however, there are specific concerns that must be considered. External drivers present a weakness to the security by allowing a user to replace the driver and thereby defeat the lock. The software authorization API, built upon the 1-Wire PD Kit, has been developed specifically for this type of application and includes linkable modules instead of external drivers.The design of the Software Authorization API is centered on the simplest use cases possible, to make integration into the software programmer's existing code easy. There are three main services provided by the API:q Initializing a 1-Wire deviceq Authenticating the deviceq Clearing a device (so it is no longer a valid part of the system)Information on the 1-Wire Software Authorization Kit can be found on the iButton web site.Software Example Search EngineMaxim continually develops 1-Wire example software applications demonstrating the APIs described in this document. Examples that do not appear in the SDKs can be found by utilizing our online Software Example Search Engine. Many of these examples (with source code) are added to the search engine first (as a separate download) before being added to its respective SDK. The search engine can search for software examples by:q1-Wire device (Thermochron, SHA iButton, etc.)q Platform (Win32, Linux, TINI, etc.)q API (TMEX, 1-Wire Public Domain, 1-Wire .NET, etc.)q Programming language (C, Java, C#, Visual Basic, Delphi, etc.)Included in the search results are a description of the program and its appropriate download link.1-Wire Software Development Interest GroupIt is recommended that 1-Wire developers join the web-based 1-Wire Software Developer's Forum. The purpose of this group is to explore, discuss, and answer questions about developing applications, tools, and uses for the 1-Wire/iButton family of products. Maxim applications engineers monitor this forum to provide answers to questions posed by the group. Announcements about updates to the APIs and kit downloads are also posted to this group.Third PartyA large volume of third-party software is available for 1-Wire devices. Some are applications produced by Maxim authorized solutions developers (ASDs) for purchase with their solution. A complete list of ASDs and a solution locator are provided on the iButton site, as well as open-source projects on public forums like .DS1990R:QuickView-- Full (PDF) Data Sheet-- Free Samples DS1991:QuickView-- Full (PDF) Data SheetDS1992:QuickView-- Full (PDF) Data Sheet-- Free Samples DS1993:QuickView-- Full (PDF) Data Sheet-- Free Samples DS1994:QuickView-- Full (PDF) Data SheetDS1995:QuickView-- Full (PDF) Data SheetDS1996:QuickView-- Full (PDF) Data SheetDS2401:QuickView-- Full (PDF) Data Sheet-- Free Samples DS2404:QuickView-- Full (PDF) Data SheetDS2405:QuickView-- Full (PDF) Data Sheet-- Free Samples DS2406:QuickView-- Full (PDF) Data Sheet-- Free Samples DS2407:QuickView-- Full (PDF) Data SheetDS2408:QuickView-- Full (PDF) Data Sheet-- Free Samples DS2409:QuickView-- Full (PDF) Data SheetDS2411:QuickView-- Full (PDF) Data Sheet-- Free Samples DS2413:QuickView-- Full (PDF) Data Sheet-- Free Samples DS2415:QuickView-- Full (PDF) Data SheetDS2417:QuickView-- Full (PDF) Data Sheet-- Free Samples DS2422:QuickView-- Full (PDF) Data SheetDS2423:QuickView-- Full (PDF) Data SheetDS2430A:QuickView-- Full (PDF) Data SheetDS2431:QuickView-- Full (PDF) Data Sheet-- Free Samples DS2432:QuickView-- Abridged Data SheetDS2433:QuickView-- Full (PDF) Data Sheet-- Free Samples DS2450:QuickView-- Full (PDF) Data Sheet-- Free Samples DS2502:QuickView-- Full (PDF) Data Sheet-- Free Samples DS2505:QuickView-- Full (PDF) Data Sheet-- Free Samples DS2506:QuickView-- Full (PDF) Data Sheet-- Free Samples DS2890:QuickView-- Full (PDF) Data SheetDS28E04-100:QuickView-- Full (PDF) Data Sheet-- Free Samples AN155, AN 155, APP155, Appnote155, Appnote 155 Copyright © by Maxim Integrated ProductsAdditional legal notices: /legal。

摘要：在没有专用总线主机(如DS2480B、DS2482)的情况下，微处理器可以轻松地产生1-Wire 时序信号。

本应用笔记给出了一个采用…C‟语言编写、支持标准速率的1-Wire主机通信基本子程序实例。

1-Wire总线的四个基本操作是：复位、写“1”、写“0”和读数据位。

字节操作可以通过反复调用位操作实现，本文提供了通过各种传输线与1-Wire器件进行可靠通信的时间参数。

引言在没有专用总线主机的情况下，微处理器可以轻松地产生1-Wire时序信号。

本应用笔记给出了一个采用C语言编写、支持标准速率的1-Wire主机通信基本子程序实例。

此外，本文也讨论了高速通信模式。

要使该实例中的代码正常运行，系统必须满足以下几点要求：1. 微处理器的通信端口必须是双向的，其输出为漏极开路，且线上具有弱上拉。

这也是所有1-Wire总线的基本要求。

关于简单的1-Wire主机微处理器电路实例，请参见应用笔记4206："为嵌入式应用选择合适的1-Wire主机"中的1类部分。

2. 微处理器必须能产生标准速度1-Wire通信所需的精确1µs延时和高速通信所需要的0.25µs延时。

3. 通信过程不能被中断。

1-Wire总线有四种基本操作：复位、写1位、写0位和读位操作。

在数据资料中，将完成一位传输的时间称为一个时隙。

于是字节传输可以通过多次调用位操作来实现，下面的表1是各个操作的简要说明以及实现这些操作所必须的步骤列表。

图1为其时序波形图。

表2给出了通常线路条件下1-Wire主机与1-Wire器件通信的推荐时间。

如果与1-Wire主机相连的器件比较特殊或者线路条件比较特殊，则可以采用最值。

请参考可下载的工作表中的系统和器件参数，确定最小值和最大值。

表1. 1-Wire操作图1. 1-Wire时序图表2. 1-Wire主机时序计算这些值的工作表可供下载。

代码实例下面代码实例都依赖于两个通用的'C'函数outp和inp，从IO端口读写字节数据。

摘要：DS2480B是带有UART主机接口的1-Wire®主机(驱动器)。

该驱动器专门为电源传输进行优化，并支持嵌入式应用中的高速模式。

DS2480B的特性之一在于其具有伸缩速率模式，允许设计者以标准速度配置1-Wire时序。

本应用笔记阐述了如何确定最佳时序配置以及如何用Windows®软件将设置参数写入芯片。

文章还将DS2480B与上拉电阻的驱动强度进行比较，详细描述见应用笔记3829。

附录一描述了如何确定最佳的配置参数。

附录二则给出了估算DS2480B可以驱动的从器件数目的算法，这取决于主机电气特性以及网络电缆的容性负载。

附录三讨论了网络过载的条件。

引言DS2480B是带UART主机接口的1-Wire主机(驱动器)。

该器件针对电源传输进行优化并支持嵌入式应用的高速模式，可以将主机从生成严格定时的1-Wire波形这一任务中解脱出来。

DS2480 B采用有源电路，缩短了时隙结束时的恢复时间。

图1给出了1-Wire驱动器部分的简化电路图。

图1. DS2480B 1-Wire驱动器的简化电路当1-Wire总线处于空闲状态时，DS2480B驱动器通过一个受控电流源提供上拉。

该电流源可被关闭(下拉期间)，可提供弱上拉电流(下拉及空闲时IWEAKPU)，或者提供一个有源上拉(上升沿时IACTPU)。

下拉电路(Q1)的压摆率可以通过软件调整。

Q2表示需要大电流的1-Wire从器件功能(如EEPROM编程或温度转换)所采用的供电电路。

Q2的功能在本应用笔记中未讨论。

为支持有效的布线配置，需要一个外部线路终端电阻RT (~100Ω)以尽量减小传输线路的影响，如反射、下冲和过冲。

然而，加入RT后会导致有源上拉在1-Wire总线完全充电之前过早关闭。

这是因为DS2480B检测的是其1-Wire引脚的电压，而非1-Wire网络从器件一侧的电压。

当1-Wire引脚电压到达内部门限值(典型值IACTPU ×RT ＝15mA × 100Ω = 1.5V)时，从器件一侧的电压将低于1-Wire引脚电压，差值为RT上的压降。

1-Wire总线协议应用作为一种单主机多从机的总线系统，在一条1-Wire总线上可挂接的从器件数量几乎不受限制。

为了不引起逻辑上的冲突，所有从器件的1-Wire总线接口都是漏极开路的，因此在使用时必须对总线外加上拉电阻（一般取5kΩ左右）。

主机对1-Wire总线的基本操作分为复位、读和写三种，其中所有的读写操作均为低位在前高位在后。

复位、读和写是1-Wire总线通信的基础，下面通过具体程序详细介绍这3种操作的时序要求。

（程序中DQ代表1-Wire总线，定义为P1.0，uchar定义为unsigned char）1 1-Wire总线的复位复位是1-Wire总线通信中最为重要的一种操作，在每次总线通信之前主机必须首先发送复位信号。

如程序1.1所示，产生复位信号时主机首先将总线拉低480～960μs然后释放，由于上拉电阻的存在，此时总线变为高电平。

1-Wire 总线器件在接收到有效跳变的15～60μs内会将总线拉低60～240μs，在此期间主机可以通过对DQ采样来判断是否有从器件挂接在当前总线上。

函数Reset（）的返回值为0表示有器件挂接在总线上，返回值为1表示没有器件挂接在总线上。

程序1.1 总线复位uchar Reset(void){uchar tdq;DQ=0; //主机拉低总线delay480μs(); //等待480μsDQ=1; //主机释放总线delay60μs(); //等待60μstdq=DQ; //主机对总线采样delay480μs(); //等待复位结束return tdq; //返回采样值}2 1-Wire总线的写操作由于只有一条I/O线，主机1-Wire总线的写操作只能逐位进行，连续写8次即可写入总线一个字节。

如程序1.2所示，当MCS-51单片机的时钟频率为12MHz时，程序中的语句_nop_();可以产生1μs的延时，调用此函数时需包含头文件“intrins.h”。

注：可能对该芯片已经进行了若干完善，参数指标已经和已出版的勘误表有所出入。

通过各种销售渠道克获悉各种芯片所做的修订。

芯片勘误表请点击：/errata 。

概述DS2482-800是 I 2C*线至1-Wire ®的桥接器件,可直接与标准(100kHz 最大值)或快速(400kHz 最大值) 的I 2C 主机连接，完成I 2C 主机和任意下游1-Wire 从器件之间的双向协议转换。

相对于任何1-Wire 从器件来说， DS2482-800是一个1-Wire 主机。

经过工厂校准的内部定时器将系统主处理器从产生严格定时的1-Wire 波形中解脱出来，且同时支持标准和高速的1-Wire 通信速率。

为了优化1-Wire 波形的产生，DS2482-800在1-Wire 的上升沿和下降沿进行了摆率控制，且该器件具有一个可编程的特性，以屏蔽某些1-Wire 从器件产生的快速应答脉冲沿。

可编程的强上拉特性支持通过1-Wire 向1-Wire 从器件供电，诸如EEPROM 和传感器。

DS2482-800将这些特性整合在一起，并提供8个独立的1-Wire I/O 通道。

I 2C 从器件地址分配是由3个二进制地址输入控制的，以解决系统中其它I 2C 从器件的可能出现的地址冲突问题。

应用无线基站中心局交换机 PBX机架服务器特性I 2C 主机接口，支持100kHz 和400kHz 的I 2C 通信 速率带有可选的有源或无源1-Wire 上拉的1-Wire 主机 I/O提供复位/在线应答、8位、1位和3位1-Wire I/O 时序独立工作的8个1-Wire I/O 通道 标准和高速的1-Wire 通信速率 1-Wire 边沿控制摆率可选的1-Wire 从器件应答脉冲下降沿屏蔽，以控 制1-Wire 总线上的快速边沿为EEPROM 、温度传感器和其它具有瞬时大电流 模式的1-Wire 从器件提供低阻抗1-Wire 强上拉。

应用笔记1551-Wire软件资源指南和驱动程序说明绪论包括iButton®在内，Dallas Semiconductor目前生产的1-Wire®器件已有30多种。

如何选择已有的应用程序接口(API)、软件范例及其它资源与这一类器件进行通信，或为某个器件选择正确的资源是一件非常令人头疼的事。

本应用笔记提供了该类资源的概述和选择指南。

本文中所描述的所有API都是免费的，而且大多数情况下还包括完整的源代码。

1-Wire 概述Dallas Semiconductor 的1-Wire总线是一种简单的信号交换架构，通过一条线路在主机与外围器件之间进行双向通信。

所有的1-Wire总线都具有一个共同的特征：无论是芯片内还是iButton内，每个器件都有一个互不重复的、工厂光刻的序列号，因此，每个器件都是唯一的。

这样就允许从众多连到同一总线的器件中独立选择任何一个器件。

当1个、2个甚至多个1-Wire器件能共用一条线路进行通信，可以采用二进制位检索法依次查找每一个器件。

一旦器件的序列号已知，通过寻址该序列号，就可以唯一地选出该器件进行通信。

所有通信的第一步都需要总线控制器发出一个‘复位’信号以使总线同步，然后选择一个受控器件进行随后的通信，这可以通过选择所有的受控器件或者选择一个特定的受控器件(利用该器件的序列号进行选择)或者通过对半检索法找到总线上的下一个受控器件来实现。

上文所提到的这些指令都是‘网络’指令或者只读存储器 (ROM)指令。

一旦一个特定的器件被选中，那么在下次复位信号发出之前，所有其它器件都被挂起而忽略随后的通信。

一旦一个器件被用于总线通信，主机就能向它发出特定的器件指令，对它进行数据读写。

这是因为每类器件具有不同的功能和不同的用途，而且一旦器件被选定，就有了唯一的协议。

虽然每类器件具有不同的协议和特征，但其工作过程却是相同的并且遵循如图1所示的工作流程。

图1. 典型的1-Wire通信流程每个受控器件的序列号的整数部分是一个8位的家族代码。