Signal Descriptions
MOTOROLA
MC68322 USER’S MANUAL
2-9
2.9 PARALLEL PORT INTERFACE
The MC68322 has 17 pins dedicated to parallel port communications. These pins are
designed to interface to an IEEE 1284-compatible or compliant host and meet all electrical
driver/receiver requirements for Level 2 compliance. All inputs are TTL-compatible and
received with Schmitt triggers with over 200 mV of hysteresis. All outputs are symmetrical
and can sink and source 16 mA at 0.4 and 3.0 V, respectively. This provides a direct
connection (through series resistors) between the MC68322 and the parallel port connector,
thus no external buffering or latching logic is required.
The following signal descriptions are for compatibility mode operation only. Control signals
carry different meanings when other IEEE 1284 modes are used. When other modes are
discussed, the IEEE 1284 signal name is provided in parentheses following the MC68322
pin name. Applications that do not require a parallel port can use these pins as
general-purpose, individually controllable I/O pins.
PIN NAME
DESCRIPTION
PD7-PD0
Parallel Port Data Bus—This 8-bit, bidirectional, three-stateable bus is used to exchange data between an
external host computer and the MC68322.
SELECTIN
Parallel Port Select In—This input signal is used by the parallel port interface to request “on-line” status
information.
STROBE
Data Strobe—This input signal indicates when valid data is present on the parallel port data bus.
AUTOFD
Parallel Port Autofeed—This input signal indicates autofeed control.
INIT
Initialization Input—This input signal is used to initialize parallel port input control.
ACK
Parallel Port Acknowledge—This output signal indicates that a transfer on the parallel port data bus is
complete.
BUSY
Parallel Port Busy—This output signal indicates that the parallel port is busy.
SELECT
Parallel Port Selected—This output signal indicates that the device on the parallel port is “on-line” or “off-line”.
PERROR
Parallel Port Error—This output signal indicates that a problem exists with the paper in the printer. It could
mean that the printer has a paper jam or is out of paper.
FAULT
Parallel Port Fault—This output signal indicates that an error condition exists with the printer. It could mean that
the printer is out of toner or has been taken offline.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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