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@@ -2,11 +2,11 @@ Kernel driver pcf8591
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=====================
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Supported chips:
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- * Philips PCF8591
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+ * Philips/NXP PCF8591
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Prefix: 'pcf8591'
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Addresses scanned: I2C 0x48 - 0x4f
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- Datasheet: Publicly available at the Philips Semiconductor website
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- http://www.semiconductors.philips.com/pip/PCF8591P.html
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+ Datasheet: Publicly available at the NXP website
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+ http://www.nxp.com/pip/PCF8591_6.html
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Authors:
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Aurelien Jarno <aurelien@aurel32.net>
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@@ -16,9 +16,10 @@ Authors:
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Description
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-----------
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+
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The PCF8591 is an 8-bit A/D and D/A converter (4 analog inputs and one
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-analog output) for the I2C bus produced by Philips Semiconductors. It
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-is designed to provide a byte I2C interface to up to 4 separate devices.
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+analog output) for the I2C bus produced by Philips Semiconductors (now NXP).
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+It is designed to provide a byte I2C interface to up to 4 separate devices.
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The PCF8591 has 4 analog inputs programmable as single-ended or
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differential inputs :
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@@ -58,8 +59,8 @@ Accessing PCF8591 via /sys interface
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-------------------------------------
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! Be careful !
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-The PCF8591 is plainly impossible to detect ! Stupid chip.
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-So every chip with address in the interval [48..4f] is
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+The PCF8591 is plainly impossible to detect! Stupid chip.
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+So every chip with address in the interval [0x48..0x4f] is
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detected as PCF8591. If you have other chips in this address
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range, the workaround is to load this module after the one
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for your others chips.
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@@ -67,19 +68,20 @@ for your others chips.
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On detection (i.e. insmod, modprobe et al.), directories are being
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created for each detected PCF8591:
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-/sys/bus/devices/<0>-<1>/
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+/sys/bus/i2c/devices/<0>-<1>/
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where <0> is the bus the chip was detected on (e. g. i2c-0)
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and <1> the chip address ([48..4f])
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Inside these directories, there are such files:
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-in0, in1, in2, in3, out0_enable, out0_output, name
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+in0_input, in1_input, in2_input, in3_input, out0_enable, out0_output, name
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Name contains chip name.
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-The in0, in1, in2 and in3 files are RO. Reading gives the value of the
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-corresponding channel. Depending on the current analog inputs configuration,
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-files in2 and/or in3 do not exist. Values range are from 0 to 255 for single
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-ended inputs and -128 to +127 for differential inputs (8-bit ADC).
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+The in0_input, in1_input, in2_input and in3_input files are RO. Reading gives
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+the value of the corresponding channel. Depending on the current analog inputs
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+configuration, files in2_input and in3_input may not exist. Values range
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+from 0 to 255 for single ended inputs and -128 to +127 for differential inputs
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+(8-bit ADC).
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The out0_enable file is RW. Reading gives "1" for analog output enabled and
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"0" for analog output disabled. Writing accepts "0" and "1" accordingly.
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