NAME

    Device::Chip::PCF8574 - chip driver for a PCF8574

DESCRIPTION

    This Device::Chip subclass provides specific communication to a NXP or
    Texas Instruments PCF8574 attached to a computer via an IC adapter.

    The reader is presumed to be familiar with the general operation of
    this chip; the documentation here will not attempt to explain or define
    chip-specific concepts or features, only the use of this module to
    access them.

MOUNT PARAMETERS

 addr

    The IC address of the device. Can be specified in decimal, octal or
    hex with leading 0 or 0x prefixes.

METHODS

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

 write

       $chip->write( $val )->get

    Sets the value of the GPIO pins, as an 8-bit integer.

    Pins set low will sink current suitable for signalling or driving an
    LED. Pins set high will source current via a weak current-source to act
    as a pull-up for an active-low input signal, such as a button.

 read

       $val = $chip->read->get

    Reads the current logic levels on the GPIO pins, returned as an 8-bit
    integer. Pins of interest as inputs should have previously been set to
    high level using the "write" method.

 as_adapter

       $adapter = $chip->as_adapter

    Returns a new object implementing the Device::Chip::Adapter interface
    which allows access to the GPIO pins of the chip as if it was a GPIO
    protocol adapter. The returned instance supports the following methods:

       $protocol = $adapter->make_protocol( 'GPIO' )
    
       $protocol->list_gpios
       $protocol->write_gpios
       $protocol->read_gpios
       $protocol->tris_gpios

AUTHOR

    Paul Evans <leonerd@leonerd.org.uk>

