NAME
Device::Chip::Authoring - guidance on writing a Device::Chip class
DESCRIPTION
This file documents the Device::Chip interface from the perspective of an author of a Device::Chip driver class; explaining how to actually write a driver instance.
It is suggested that a driver for a particular hardware chip or module provides a concrete class named within the Device::Chip heirarchy, adding the basic name of the chip or module as a suffix; for example the driver for a Maxim MAX7219 LED driver would be called:
package Device::Chip::MAX7219;The Device::Class package provides a base class that such a specific implementation class could use as a superclass, but it is not required to. The important detail is that it provides the interface described by the main Device::Class documentation. The documentation in this file mostly concerns itself with the abilities and utilities provided by the base class implementation.
METADATA METHODS
The following class-level methods provide information about the chip and how to drive it. They will be invoked by methods in the base classes to perform the common boilerplate configuration steps required to set up the adapter to communicate with the chip.
PROTOCOL
$pname = Device::Chip->PROTOCOLThis method is invoked by "mount" in Device::Chip to enquire which protocol the chip wishes to use, as the first stage of configuring the adapter. This method should return a protocol name suitable for "make_protocol" in Device::Chip::Adapter.
PNAME_options
%options = $chip->PNAME_options( %params )Optional methods of this general form (where PNAME is the protocol name being used) will be called by "mount" in Device::Chip once the protocol instance is available. If such a method exists, the values it returns will be used to invoke the protocol's configure method. It is passed a copy of the parameters that were given to the mount method.
BASE CLASS METHODS
The following methods are provided by the Device::Chip base class itself as a convenience to chip driver authors.
adapter
$adapter = $chip->adapterReturns the current adapter that the chip is mounted on. This will be some instance implementing the companion interface, Device::Chip::Adapter.
protocol
$protocol = $chip->protocolReturns the adapter protocol module that the chip driver code will use to actually communicate with the chip.