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-Kernel driver pcf8591
-=====================
-
-Supported chips:
- * Philips/NXP PCF8591
- Prefix: 'pcf8591'
- Addresses scanned: none
- Datasheet: Publicly available at the NXP website
- http://www.nxp.com/pip/PCF8591_6.html
-
-Authors:
- Aurelien Jarno <aurelien@aurel32.net>
- valuable contributions by Jan M. Sendler <sendler@sendler.de>,
- Jean Delvare <khali@linux-fr.org>
-
-
-Description
------------
-
-The PCF8591 is an 8-bit A/D and D/A converter (4 analog inputs and one
-analog output) for the I2C bus produced by Philips Semiconductors (now NXP).
-It is designed to provide a byte I2C interface to up to 4 separate devices.
-
-The PCF8591 has 4 analog inputs programmable as single-ended or
-differential inputs :
-- mode 0 : four single ended inputs
- Pins AIN0 to AIN3 are single ended inputs for channels 0 to 3
-
-- mode 1 : three differential inputs
- Pins AIN3 is the common negative differential input
- Pins AIN0 to AIN2 are positive differential inputs for channels 0 to 2
-
-- mode 2 : single ended and differential mixed
- Pins AIN0 and AIN1 are single ended inputs for channels 0 and 1
- Pins AIN2 is the positive differential input for channel 3
- Pins AIN3 is the negative differential input for channel 3
-
-- mode 3 : two differential inputs
- Pins AIN0 is the positive differential input for channel 0
- Pins AIN1 is the negative differential input for channel 0
- Pins AIN2 is the positive differential input for channel 1
- Pins AIN3 is the negative differential input for channel 1
-
-See the datasheet for details.
-
-Module parameters
------------------
-
-* input_mode int
-
- Analog input mode:
- 0 = four single ended inputs
- 1 = three differential inputs
- 2 = single ended and differential mixed
- 3 = two differential inputs
-
-
-Accessing PCF8591 via /sys interface
--------------------------------------
-
-The PCF8591 is plainly impossible to detect! Thus the driver won't even
-try. You have to explicitly instantiate the device at the relevant
-address (in the interval [0x48..0x4f]) either through platform data, or
-using the sysfs interface. See Documentation/i2c/instantiating-devices
-for details.
-
-Directories are being created for each instantiated PCF8591:
-
-/sys/bus/i2c/devices/<0>-<1>/
-where <0> is the bus the chip is connected to (e. g. i2c-0)
-and <1> the chip address ([48..4f])
-
-Inside these directories, there are such files:
-in0_input, in1_input, in2_input, in3_input, out0_enable, out0_output, name
-
-Name contains chip name.
-
-The in0_input, in1_input, in2_input and in3_input files are RO. Reading gives
-the value of the corresponding channel. Depending on the current analog inputs
-configuration, files in2_input and in3_input may not exist. Values range
-from 0 to 255 for single ended inputs and -128 to +127 for differential inputs
-(8-bit ADC).
-
-The out0_enable file is RW. Reading gives "1" for analog output enabled and
-"0" for analog output disabled. Writing accepts "0" and "1" accordingly.
-
-The out0_output file is RW. Writing a number between 0 and 255 (8-bit DAC), send
-the value to the digital-to-analog converter. Note that a voltage will
-only appears on AOUT pin if aout0_enable equals 1. Reading returns the last
-value written.