diff --git a/doc/chips/mic74 b/doc/chips/mic74 new file mode 100644 index 00000000..d6c26a12 --- /dev/null +++ b/doc/chips/mic74 @@ -0,0 +1,57 @@ +Kernel driver `mic74.o' +========================= + +Status: Beta + +Supported chips: + * Micrel MIC74 + Prefix: `mic74' + Addresses scanned: I2C 0x20 - 0x27 (inclusive) + Datasheet: Publicly available at the Micrel website + http://www.micrel.com/ + +Authors: zebo25 + mds (cleanups and this doc) + +Module Parameters +----------------- + + +Description +----------- +The MIC74 is an 8-bit I/O expander for the I2C bus. +Semiconductors. It is designed to provide a byte I2C interface to up to 8 +separate devices. + +This device consists of a quasi-bidirectionnal port. Each of the eight I/Os +can be independently used as an input or output. + +The driver does not initialize the ports, they will be at their +power-up defaults, or however the BIOS programmed them. + +For more information see the datasheet. + + +Accessing MIC74 via /proc interface +------------------------------------- + +! Be careful ! +The chip is plainly impossible to detect ! Stupid chip. +So every chip with adress in the interval [20..27] could be +detected as an MIC74 or a PCF8574. Don't load both drivers. +If you have other chips in this address +range, the workaround is to load this module after the one +for your others chips. + +On detection, directories are created for each detected chip: + + /proc/sys/dev/sensors/mic74-<0>-<1>/ + where <0> is the bus the chip was detected on (e. g. i2c-0) + and <1> the chip address [20..27]: + ./mic74-i2c-0-27/ + +Inside these directories, there are seven files each, +one for each of the seven registers in the device. + +At this point you really need the datasheet. +It should be self-explanatory which file is for which register.