The W91284PIC is a an integrated solution that can be used to provide an IEEE Std. 1284-1994 interface for any parallel port peripheral. Specifically, the W91284PIC can be used with appropriate firmware to provide a fully compliant IEEE 1284 peripheral interface. This interface provides fast, bi-directional data transfer and control information when connected to a 1284 host parallel port. This IC is suitable for providing the peripheral interface for a wide variety of devices such as printers, scanners, multifunction and any other parallel port peripheral.
W91284PIC Block Diagram
of the W91284PIC implement the physical level
hardware state machines and registers that interact with the host side
of the interface and provide data transfer between the parallel port and
the client side peripheral bus.
Port Sharing - Daisy Chaining
In addition to these IEEE 1284-1994 modes the W91284PIC provides support for a pass-through port that allows a printer or other peripheral to share the same host PC parallel port. This is provided via the IEEE P1284.3 port sharing standard. This is also known as Daisy Chaining. Figure 2 shows and example of 4 daisy chain devices connected together sharing a single parallel port. At the end of the chain is a 'legacy' printer device.
The W91284PIC implements the IEEE 1284 peripheral interface state machine in hardware. The state machine handles all of the 1284 signaling on the parallel port interface and acts as a data "bridge" to the client interface. The microcontroller firmware is not involved with the 1284 signaling.
There are a number of parameter registers that the firmware can set that will control the basic operation of the interface. These parameters include:
provides an IEEE 1284 Level II electrical interface, needing no external
transceivers to interface to the cable. For peripherals requiring added
protection there is support for external 74ACT1284 transceivers. As shown
in figure 1, the W91284PIC interfaces to the 1284 parallel port on one
side, and the client's peripheral interface on the other. From the client
side, the W91284PIC looks like a 'generic' microcontroller interface.
The basic operation of the interface is controlled via settings in the
W91284PIC control registers. Once enabled, the W91284PIC provides all
of the handshaking and data transfer to and from the parallel port. This
data is transferred across client interface via DMA or PIO to the W91284PIC's
transmit and receive FIFOs. It is not necessary for the client processor
to have any knowledge of, or implement any of the IEEE 1284 parallel port
protocols. This is all managed via the W91284PIC state machines.
Is the 1284PIC Macrocell still available?
Q. Do you
have a development board?
© 1998-2004 Warp Nine Engineering