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- Kernel driver pca9539
- =====================
- NOTE: this driver is deprecated and will be dropped soon, use
- drivers/gpio/pca9539.c instead.
- Supported chips:
- * Philips PCA9539
- Prefix: 'pca9539'
- Addresses scanned: 0x74 - 0x77
- Datasheet:
- http://www.semiconductors.philips.com/acrobat/datasheets/PCA9539_2.pdf
- Author: Ben Gardner <bgardner@wabtec.com>
- Description
- -----------
- The Philips PCA9539 is a 16 bit low power I/O device.
- All 16 lines can be individually configured as an input or output.
- The input sense can also be inverted.
- The 16 lines are split between two bytes.
- Sysfs entries
- -------------
- Each is a byte that maps to the 8 I/O bits.
- A '0' suffix is for bits 0-7, while '1' is for bits 8-15.
- input[01] - read the current value
- output[01] - sets the output value
- direction[01] - direction of each bit: 1=input, 0=output
- invert[01] - toggle the input bit sense
- input reads the actual state of the line and is always available.
- The direction defaults to input for all channels.
- General Remarks
- ---------------
- Note that each output, direction, and invert entry controls 8 lines.
- You should use the read, modify, write sequence.
- For example. to set output bit 0 of 1.
- val=$(cat output0)
- val=$(( $val | 1 ))
- echo $val > output0
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