BIT 1 AUTOFD - AUTOFEED
This bit is inverted and output onto the nAUTOFD output. A logic 1 causes the printer to generate a line
feed after each line is printed. A logic 0 means no autofeed.
BIT 2 nINIT - nINITIATE OUTPUT
This bit is output onto the nINIT output without inversion.
BIT 3 SLCTIN - PRINTER SELECT INPUT
This bit is inverted and output onto the nSLCTIN output. A logic 1 on this bit selects the printer; a logic 0
means the printer is not selected.
BIT 4 IRQE - INTERRUPT REQUEST ENABLE
The interrupt request enable bit when set to a high level may be used to enable interrupt requests from the
Parallel Port to the CPU. An interrupt request is generated on the IRQ port by a positive going nACK
input. When the IRQE bit is programmed low the IRQ is disabled.
BIT 5 PCD - PARALLEL CONTROL DIRECTION
Parallel Control Direction is not valid in printer mode. In printer mode, the direction is always out
regardless of the state of this bit. In bi-directional, EPP or ECP mode, a logic 0 means that the printer port
is in output mode (write); a logic 1 means that the printer port is in input mode (read).
Bits 6 and 7 during a read are a low level, and cannot be written.
EPP ADDRESS PORT
ADDRESS OFFSET = 03H
The EPP Address Port is located at an offset of '03H' from the base address. The address register is
cleared at initialization by RESET. During a WRITE operation, the contents of the internal data bus DB0-
DB7 are buffered (non inverting) and output onto the PD0 - PD7 ports. An LPC I/O write cycle causes an
EPP ADDRESS WRITE cycle to be performed, during which the data is latched for the duration of the
EPP write cycle. During a READ operation, PD0 - PD7 ports are read. An LPC I/O read cycle causes an
EPP ADDRESS READ cycle to be performed and the data output to the host CPU, the deassertion of
ADDRSTB latches the PData for the duration of the read cycle. This register is only available in EPP
mode.
EPP DATA PORT 0
ADDRESS OFFSET = 04H
The EPP Data Port 0 is located at an offset of '04H' from the base address. The data register is cleared at
initialization by RESET. During a WRITE operation, the contents of the internal data bus DB0-DB7 are
buffered (non inverting) and output onto the PD0 - PD7 ports. An LPC I/O write cycle causes an EPP
DATA WRITE cycle to be performed, during which the data is latched for the duration of the EPP write
cycle. During a READ operation, PD0 - PD7 ports are read. An LPC I/O read cycle causes an EPP READ
cycle to be performed and the data output to the host CPU, the deassertion of DATASTB latches the
PData for the duration of the read cycle. This register is only available in EPP mode.
EPP DATA PORT 1
ADDRESS OFFSET = 05H
The EPP Data Port 1 is located at an offset of '05H' from the base address. Refer to EPP DATA PORT 0
for a description of operation. This register is only available in EPP mode.
EPP DATA PORT 2
ADDRESS OFFSET = 06H
The EPP Data Port 2 is located at an offset of '06H' from the base address. Refer to EPP DATA PORT 0
for a description of operation. This register is only available in EPP mode.
SMSC LPC47B27x
- 77 -
Rev. 08-10-04
DATASHEET
SMSC [ SMSC CORPORATION ]
