NAME
Device::Chip::PCF8574 - chip driver for a PCF8574 or PCA8574
DESCRIPTION
This Device::Chip subclass provides specific communication to a NXP or
Texas Instruments PCF8574 attached to a computer via an I�C adapter.
Due to hardware similarity this can also drive a PCA8574.
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 I�C address of the device. Can be specified in decimal, octal or
hex with leading 0 or 0x prefixes.
METHODS
The following methods documented in an await expression return Future
instances.
write
await $chip->write( $val );
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 = await $chip->read;
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 = await $adapter->make_protocol( 'GPIO' )
$protocol->list_gpios
await $protocol->write_gpios
await $protocol->read_gpios
await $protocol->tris_gpios
AUTHOR
Paul Evans <
[email protected]>
