Paul Evans

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:

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 <leonerd@leonerd.org.uk>