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涎 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涎 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 <leonerd@leonerd.org.uk>