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= Inter-Integrated Circuit (I2C) = 
The Inter-Integrated Circuit by Philips is a popular interconnect (typically on-board) used on embedded processors as well as modern computers consisting of 2-wires (other than ground, power, and optional interrupts):
 * SCL - clock
 * SDA - data

An I2C bus may be multi-master and support interrupts from the device to host controller.

Reference:
 * http://en.wikipedia.org/wiki/I%C2%B2C

== On-Board I2C Host Controllers ==
Various Gateworks boards support 3.3V TTL I2C to an off-board expansion connector:
||= Family =||= Board   =||= Device =||= I2C Buffer Enable =||= Connector =||
|| Venice   || GW740x    || I2C3 /dev/i2c-2  || - || J8 MIPI: J8.34 SCL, J8.36 SDA||
||          ||           || I2C4 /dev/i2c-3  || - || J14 DIO: J14.5 SCL, J14.6 SDA ||
||          || GW730x    || I2C3 /dev/i2c-2  || - || J9 (shared with MIPI J17) ||
||          || GW720x    || I2C3 /dev/i2c-2  || - || J5 (shared with MIPI J4) ||
||          || GW710x    || I2C3 /dev/i2c-3  || - || J25 ||
|| ||
|| Newport  || GW610x    || TWSI1 /dev/i2c-1 || - || J10 (dedicated SDA/GND/SCL) 3.3V TTL ||
||          || GW620x    || TWSI1 /dev/i2c-1 || - || J11 (dedicated SDA/GND/SCL) 3.3V TTL (build option for 5V TTL) ||
||          || GW630x    || TWSI1 /dev/i2c-1 || - || J14 (dedicated SDA/GND/SCL) 3.3V TTL (build option for 5V TTL) ||
||          || GW640x    || TWSI1 /dev/i2c-1 || - || J14 (dedicated SDA/GND/SCL) 3.3V TTL (build option for 5V TTL) ||
|| ||
|| Ventana  || GW54xx-B+ || I2C3 /dev/i2c-2  || gpio101  || J16 (shared with DIO0/DIO1) ^^^1^^^ ||
||          || GW53xx-B+ || I2C3 /dev/i2c-2  || gpio101  || J4 (shared with DIO0/DIO1) ^^^1^^^ ||
||          || GW52xx-C+ || I2C3 /dev/i2c-2  || - || J4 (shared with DIO0/DIO1) ^^^1^^^ ^^^2^^^ ||
||          || GW551x    || I2C3 /dev/i2c-2  || - || J3 (dedicated SDA/SCL/GND) ||
 1. Ventana off-board I2C shares pins with MX6_DIO0 / MX6_DIO1 which need to be configured as inputs to use I2C
 2. requires resistor loading option

Please consult the ​Hardware Manuals for pinouts

See also:
 * [wiki:ventana/DigitalIO#I2Csupport Ventana I2C]

== USB I2C Host Controllers ==
A I2C master can also be added via USB expansion. For example:
 * [http://trac.gateworks.com/wiki/expansion/gw16113 GW16113 firmware-flexible USB 2.0 FS expansion]
 * [http://www.commell.com.tw/product/Peripheral/PCI%20Express%20mini%20card/MPX-24794S.HTM Commell MPX-24794S USB 2.0 FS SPI/I2C/GPIO expansion]

== Linux Kernel API ==
See [wiki:linux/i2c]