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I²C (Inter-Integrated Circuit), pronounced ''I-squared-C'', is a multi-master, multi-slave, single-ended, serial computer bus invented by Philips Semiconductor (now NXP Semiconductors). It is typically used for attaching lower-speed peripheral ICs to processors and microcontrollers. Alternatively I²C is spelled ''I2C'' (pronounced ''I-two-C'') or ''IIC'' (pronounced ''I-I-C''). Since October 10, 2006, no licensing fees are required to implement the I²C protocol. However, fees are still required to obtain I²C slave addresses allocated by NXP.〔(I²C Licensing Information )〕 Several competitors, such as Siemens AG (later Infineon Technologies AG, now Intel mobile communications), NEC, Texas Instruments, STMicroelectronics (formerly SGS-Thomson), Motorola (later Freescale), and Intersil, have introduced compatible I²C products to the market since the mid-1990s. SMBus, defined by Intel in 1995, is a subset of I²C that defines the protocols more strictly. One purpose of SMBus is to promote robustness and interoperability. Accordingly, modern I²C systems incorporate policies and rules from SMBus, sometimes supporting both I²C and SMBus, requiring only minimal reconfiguration. ==Revisions== * In 1982, the original 100-kHz I²C system was created as a simple internal bus system for building control electronics with various Philips chips. * In 1992, Version 1 added 400-kHz ''Fast-mode (Fm)'' and a 10-bit addressing mode to increase capacity to 1008 nodes. This was the first standardized version. * In 1998, Version 2 added 3.4-MHz ''High-speed mode (Hs)'' with power-saving requirements for electric voltage and current. * In 2000, Version 2.1 introduced a minor cleanup of version 2. * In 2007, Version 3 added 1-MHz ''Fast-mode plus (Fm+)'', and a device ID mechanism. * In 2012, Version 4 added 5-MHz ''Ultra Fast-mode (UFm)'' for new USDA and USCL lines using push-pull logic without pull-up resistors, and added assigned manufacturer ID table. * In 2012, Version 5 corrected mistakes. * In 2014, Version 6 corrected two graphs. This is the most recent standard.〔(Official I2C Specification Version 6 )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「I²C」の詳細全文を読む スポンサード リンク
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