NAME

NAME
`Device::Chip::MCP23x17' - chip driver for the MCP23x17 family

SYNOPSIS
use Device::Chip::MCP23S17;

use constant { HIGH => 0xFFFF, LOW => 0 };

my $chip = Device::Chip::MCP23S17->new;
$chip->mount( Device::Chip::Adapter::...->new )->get;

foreach my $bit ( 0 .. 15 ) {
$chip->write_gpio( HIGH, 1 << $bit )->get;
sleep 1;
$chip->write_gpio( LOW, 1 << $bit )->get;
}

DESCRIPTION
This Device::Chip subclass provides specific communication to the
Microchip MCP23x17 family of chips.

This module itself is an abstract base; to talk to a specific chip see
one of the following subclasses:

MCP23S17 over SPI - see Device::Chip::MCP23S17

Aside from the method of communication with the actual chip hardware,
these modules all provide the same higher-level API to the containing
application.

This module currently only supports a chip running in the `IOCON.BANK=0'
configuration.

MOUNT PARAMETERS
reset
The name of the GPIO line on the adapter that is connected to the
`RESET#' pin of the chip, if there is one. This will be used by the
reset method.

METHODS
The following methods documented with a trailing call to `->get' return
Future instances.

Each method that takes a `$mask' parameter uses it to select which IO
pins are affected. The mask is a 16-bit integer; selecting only those
pins for which bits are set. The lower 8 bits relate to the `GPA' pins,
the higher 8 to the `GPB' pins. Pins that are not selected by the mask
remain unaffected.

reset
$chip->reset->get;

Resets the cached register values back to their power-up defaults.

Additionally, if the `reset' mount parameter is defined, pulses the
`RESET#' pin of the chip.

write_gpio
$chip->write_gpio( $val, $mask )->get

Sets the pins named in the `$mask' to be outputs, and sets their values
from the bits in `$val'. Both values are 16-bit integers.

read_gpio
$val = $chip->read_gpio( $mask )->get

Sets the pins named in the `$mask' to be inputs, and reads the current
pin values of them. The mask and the return value are 16-bit integers.

tris_gpio
$chip->tris_gpio( $mask )

Sets the pins named in the `$mask' to be inputs ("tristate"). The mask
is a 16-bit integer.

set_input_polarity
$chip->set_input_polarity( $pol, $mask )

Sets the input polarity of the pins given by `$mask' to be the values
given in `$pol'. Pins associated with bits set in `$pol' will read with
an inverted sense. Both values are 16-bit integers.

set_input_pullup
$chip->set_input_pullup( $pullup, $mask )

Enables or disables the input pullup resistors on the pins given by
`$mask' as per the values given by `$pullup'. Both values are 16-bit
integers.

TODO
* Wrap the interrupt-related registers - `GPINTEN', `DEFVAL',
`INTCON', `INTF', `INTCAP'. Support the interrupt-related bits in
`IOCON' - `MIRROR', `ODR', `INTPOL'.

* Support the general configuration bits in the `IOCON' register -
`DISSLW', `HAEN'.

* Consider how easy/hard or indeed how useful it might be to support
`IOCON.BANK=1' configuration.

* Create a Device::Chip::Adapter instance to represent the GPIO pins
as a standard adapter.

AUTHOR
Paul Evans <[email protected]>