--- name: "iic" section: "4" platform: "openbsd" package: "man" version: "8.0-current-20261101" release: "OpenBSD 8.0-current (2026-11-01)" platforms: ["linux", "freebsd", "openbsd"] url: "https://new.carta.tech/iic" --- # iic(4) Inter IC (I2C) bus ## NAME **iic** – Inter IC (I2C) bus ## SYNOPSIS **iic\* at kiic? # macppc** **iic\* at piic? # macppc** **iic\* at smu? # macppc** **iic\* at alipm? # alpha i386 sparc64** **iic\* at amdiic? # amd64 i386** **iic\* at amdpm? # i386** **iic\* at glxpcib? # i386** **iic\* at gscsio? # i386** **iic\* at ichiic? # amd64 i386** **iic\* at iicmux? # arm64** **iic\* at nviic? # amd64 i386** **iic\* at pcamux? # arm64** **iic\* at pcfiic? # sparc64** **iic\* at piixpm? # amd64 i386** **iic\* at viapm? # amd64 i386** **iic\* at gpioiic? # i386** **iic\* at gdiumiic? # loongson** **iic\* at tsciic? # alpha** **iic\* at amliic? # arm64** **iic\* at apliic? # arm64** **iic\* at bcmbsc? # arm64 armv7** **iic\* at dwiic? # amd64 arm64** **iic\* at octiic? # octeon** **iic\* at imxiic? # arm64 armv7** **iic\* at mviic? # arm64** **iic\* at rkiic? # arm64 armv7** **iic\* at qciic? # arm64** **iic\* at sxitwi? # arm64 armv7** **iic\* at mpfiic? # riscv64** **iic\* at ociic? # riscv64** **iic\* at smtiic? # riscv64** ## DESCRIPTION I2C is a two-wire bus developed by Philips used for connecting integrated circuits. It is commonly used for connecting devices such as EEPROMs, temperature sensors, fan controllers, real-time clocks, tuners, and other types of integrated circuits. The **iic** driver provides a uniform programming interface layer between I2C master controllers and various I2C slave devices. Each I2C master controller attaches an **iic** framework; several slave devices can then be attached to the **iic** bus. All I2C slave devices are uniquely identified by the address on the bus. The master accesses a particular slave device using its address. Devices are found on the bus using a sophisticated scanning routine which attempts to identify commonly available devices. On other machines (such as sparc64 and macppc) where the machine ROM supplies a list of I2C devices, that list is used instead. System Management Bus (SMBus) protocol is also supported by emulating it with the I2C commands. ## SUPPORTED MASTERS - [alipm(4)](/alipm/4.md) Acer Labs M7101 SMBus controller - [amdiic(4)](/amdiic/4.md) AMD-8111 SMBus controller - [amdpm(4)](/amdpm/4.md) AMD-756/766/768/8111 Power Management and SMBus controller - [amliic(4)](/amliic/4.md) Amlogic I2C controller - [apliic(4)](/apliic/4.md) Apple I2C controller - [bcmbsc(4)](/bcmbsc/4.md) Broadcom Serial Control controller - [dwiic(4)](/dwiic/4.md) Synopsys DesignWare I2C controller - [glxpcib(4)](/glxpcib/4.md) AMD CS5536 PCI-ISA bridge with timecounter, watchdog timer, and GPIO - [gpioiic(4)](/gpioiic/4.md) GPIO I2C controller - [gscsio(4)](/gscsio/4.md) National Semiconductor Geode SC1100 I2C controller - [ichiic(4)](/ichiic/4.md) Intel ICH SMBus controller - [imxiic(4)](/imxiic/4.md) Freescale i.MX I2C controller - [kiic(4)](/kiic/4.md) Apple Kauai I2C controller - [mpfiic(4)](/mpfiic/4.md) Microchip PolarFire SoC MSS I2C controller - [mviic(4)](/mviic/4.md) Marvell Armada 3700 onboard I2C controller - [nviic(4)](/nviic/4.md) NVIDIA nForce2/3/4 SMBus controller - [ociic(4)](/ociic/4.md) OpenCores I2C controller - [octiic(4)](/octiic/4.md) OCTEON two-wire serial interface - [pcfiic(4)](/pcfiic/4.md) Philips PCF8584 I2C controller - [piic(4)](/piic/4.md) Apple via-pmu I2C controller - [piixpm(4)](/piixpm/4.md) Intel PIIX SMBus controller - [rkiic(4)](/rkiic/4.md) Rockchip I2C controller - [qciic(4)](/qciic/4.md) Qualcomm Snapdragon GENI I2C controller - [rkpmic(4)](/rkpmic/4.md) Rockchip RK8xx Power Management IC - [smtiic(4)](/smtiic/4.md) SpacemiT I2C controller - [smu(4)](/smu/4.md) Apple System Management Unit - [sxitwi(4)](/sxitwi/4.md) Allwinner Two Wire Interface controller - [tsciic(4)](/tsciic/4.md) DECchip 21272 and 21274 Core Logic chipset I2C controller - [viapm(4)](/viapm/4.md) VIA SMBus controller ## SUPPORTED SLAVES - [abcrtc(4)](/abcrtc/4.md) Abracon AB1805 real-time clock - [adc(4)](/adc/4.md) Analog Devices AD7416/AD7417/7418 temperature sensor - [adl(4)](/adl/4.md) Andigilog aSC7621 temperature, voltage, and fan sensor - [admcts(4)](/admcts/4.md) Analog Devices ADM1026 temperature and voltage sensor - [admlc(4)](/admlc/4.md) Analog Devices ADM1024 temperature and voltage sensor - [admtemp(4)](/admtemp/4.md) Analog Devices ADM1021 temperature sensor - [admtm(4)](/admtm/4.md) Analog Devices ADM1025 temperature and voltage sensor - [admtmp(4)](/admtmp/4.md) Analog Devices ADM1030 temperature sensor - [admtt(4)](/admtt/4.md) Analog Devices ADM1031 temperature sensor - [adt(4)](/adt/4.md) Analog Devices ADT7460 temperature, voltage, and fan sensor - [adtfsm(4)](/adtfsm/4.md) Analog Devices ADT7462 temperature, voltage, and fan sensor - [andl(4)](/andl/4.md) Andigilog aSC7611 temperature, voltage, and fan sensor - [asbtm(4)](/asbtm/4.md) Asus ASB 100 temperature sensor - [asms(4)](/asms/4.md) Apple sudden motion sensor - [axppmic(4)](/axppmic/4.md) X-Powers AXP Power Management IC - [bdpmic(4)](/bdpmic/4.md) ROHM BD718x7 Power Management IC - [bgw(4)](/bgw/4.md) Bosch motion sensor - [ccpmic(4)](/ccpmic/4.md) Intel Crystal Cove Power Management IC - [cwfg(4)](/cwfg/4.md) CellWise CW201x fuel gauge - [dapmic(4)](/dapmic/4.md) Dialog DA9063 Power Management IC - [dsxrtc(4)](/dsxrtc/4.md) Maxim DS3231/DS3232 real-time clock - [ecadc(4)](/ecadc/4.md) environmental monitoring subsystem temperature sensor - [escodec(4)](/escodec/4.md) Everest Semiconductor ES8316 audio codec - [fanpwr(4)](/fanpwr/4.md) Fairchild FAN53555 voltage regulator - [fcu(4)](/fcu/4.md) Apple Fan Control Unit sensor device - [fintek(4)](/fintek/4.md) Fintek F75375 temperature sensor - [fusbtc(4)](/fusbtc/4.md) Fairchild FUSB302 USB Type-C Port controller - [glenv(4)](/glenv/4.md) Genesys Logic GL518SM temperature, voltage, and fan sensor - [iatp(4)](/iatp/4.md) Atmel maXTouch touchpad and touchscreen - [ietp(4)](/ietp/4.md) Elantech touchpad - [ihidev(4)](/ihidev/4.md) HID over I2C support - [ipmi(4)](/ipmi/4.md) Intelligent Platform Management Interface driver - [islrtc(4)](/islrtc/4.md) Intersil ISL1208/1218 real-time clock - [lisa(4)](/lisa/4.md) STMicroelectronics LIS331DL MEMS motion sensor - [lm(4)](/lm/4.md) National Semiconductor LM78/79/81 temperature, voltage, and fan sensor - [lmenv(4)](/lmenv/4.md) National Semiconductor LM87 temperature, voltage, and fan sensor - [lmn(4)](/lmn/4.md) National Semiconductor LM93 temperature, voltage, and fan sensor - [lmtemp(4)](/lmtemp/4.md) National Semiconductor LM75/LM76/LM77 temperature sensor - [maxds(4)](/maxds/4.md) Maxim DS1624/DS1631/DS1721 temperature sensor - [maxrtc(4)](/maxrtc/4.md) Maxim DS1307/DS1339 real-time clock - [maxtmp(4)](/maxtmp/4.md) Maxim MAX6642/MAX6690 temperature sensor - [mcprtc(4)](/mcprtc/4.md) Microchip MCP79400 real-time clock - [mfokrtc(4)](/mfokrtc/4.md) M41T8x real-time clock - [nvt(4)](/nvt/4.md) Nuvoton W83795G/ADG temperature, voltage, and fan sensor - [pcagpio(4)](/pcagpio/4.md) Philips PCA955\[4567\] GPIO controller - [pcaled(4)](/pcaled/4.md) Philips PCA9532/9552 GPIO LED dimmer - [pcamux(4)](/pcamux/4.md) Philips PCA954\[678\] I2C switch/mux - [pcfadc(4)](/pcfadc/4.md) Philips PCF8591 temperature sensor - [pcfrtc(4)](/pcfrtc/4.md) NXP PCF8523 real-time clock - [pcxrtc(4)](/pcxrtc/4.md) NXP PCF8563 real-time clock - [pcyrtc(4)](/pcyrtc/4.md) NXP PCF85063A/TP real-time clock - [pijuice(4)](/pijuice/4.md) PiJuice HAT UPS - [ricohrtc(4)](/ricohrtc/4.md) Ricoh RS5C372 real-time clock - [rkpmic(4)](/rkpmic/4.md) Rockchip RK8xx Power Management IC - [sdtemp(4)](/sdtemp/4.md) SO-DIMM (JC-42.4) temperature sensor - [sncodec(4)](/sncodec/4.md) Texas Instruments TAS2764 digital amplifier - [spdmem(4)](/spdmem/4.md) Serial Presence Detect memory - [ssdfb(4)](/ssdfb/4.md) Solomon Systech SSD1306/SSD1309 OLED display module - stsec(4) ST7 embedded controller - [sypwr(4)](/sypwr/4.md) Silergy SY8106A voltage regulator - [tascodec(4)](/tascodec/4.md) Texas Instruments TAS2770 digital amplifier - [tcpci(4)](/tcpci/4.md) USB Type-C Port Controller Interface - [tda(4)](/tda/4.md) Philips TDA8444 fan controller - [thmc(4)](/thmc/4.md) TI THMC50, Analog ADM1022/1028 temperature sensor - [tipd(4)](/tipd/4.md) TI USB Type-C power delivery controller - [tipmic(4)](/tipmic/4.md) Intel Dollar Cove TI Power Management IC - [titmp(4)](/titmp/4.md) TI TMP451 temperature sensor - [tsl(4)](/tsl/4.md) TAOS TSL2560/61 light sensor - [wbenv(4)](/wbenv/4.md) Winbond W83L784R/W83L785R/W83L785TS-L temperature, voltage, and fan sensor - [wbng(4)](/wbng/4.md) Winbond W83793G temperature, voltage, and fan sensor ## SEE ALSO [iicmux(4)](/iicmux/4.md), [intro(4)](/intro/4.md), iic(9) ## HISTORY The I2C framework first appeared in NetBSD 2.0. OpenBSD support was added in OpenBSD 3.6. I2C bus scanning was added in OpenBSD 3.9. ## AUTHORS The I2C framework was written by Steve C. Woodford and Jason R. Thorpe for NetBSD and then ported to OpenBSD by Alexander Yurchenko ⟨*grange@openbsd.org*⟩.