NM9805CV ETC [List of Unclassifed Manufacturers], NM9805CV Datasheet - Page 11

• Manufacturer Part Number: NM9805CV
• Description: PCI + 1284 Printer Port
• Manufacturer: ETC [List of Unclassifed Manufacturers]

Config-B Register
Configuration B register. This register allows software
to control the selecting of interrupts. A read-write imple-
mentation implies a “software-configurable” device.
Reading this register returns the configured interrupt
and interrupt pin state. If a value is not set to 000 (the
jumper-default) then it is assumed that the value in the
register is correct and software will use the default in-
terrupt.
Config-B Bit-7:
Not used, set to “0”.
Config-B Bit-6:
0 = Configured printer interrupt pin is low.
1 = Configured printer interrupt pin is high.
Config-B Bit 7-0:
Interrupt pin select register.
Extended Control Register (ECR)
This register controls the mode selection and DMA op-
eration.
Mode changes
After hardware reset, PS/2 mode is selected as default
mode. It is required to select mode 000 or 001 between
any other mode configuration.
Rev. 1.1
Bit-7
0
0
0
0
1
1
1
1
Bit-6
0
0
1
1
0
0
1
1
Bit-5
0
1
0
1
0
1
0
1
PPF (FIFO mode)
Config A/B enable
Operating Mode
FIFO test
Not used
PS/2
SPP
ECP
EPP
Mode “000”
SPP/Centronics/Compatible Mode
Forward direction only. The direction bit is forced to “0”
and PD7-PD0 are set to output direction. The Nm9805
is under software control. This mode defines the proto-
col used by most PCs to transfer data to a printer. It is
commonly called the Centronics mode and is the method
utilized with the standard parallel port. Data is placed
on the PD7-PD0 ports, the printer status is checked via
DSR register. If no error condition is flagged and printer
is not busy, software toggles the nSTROBE pin to latch
the PD7-PD0 data into printer. This operating cycle con-
tinues when printer/peripheral issues data acknowledge
signal (pulses the ACK and nBUSY pin).
Nibble Mode
The nibble mode is the most common way to get re-
verse channel data from a printer or peripheral. This
mode is usually combined with the Centronics mode or
a proprietary forward channel mode to create a bi-di-
rectional channel. In this mode printer status bits are
used as nibble bits.
Bits order for nibble mode
Mode “001”
PS/2, Byte Mode
The byte mode protocol is used to transfer bi-directional
data via PD7-PD0 ports without FIFO utilization. The
direction of the port is controlled with DIR bit in DCR
register. PS/2-byte use SPP protocol for data transfer.
DCR Bit-5:
0 = PD7-PD0 pins are out put mode.
1 = PD7-PD0 pins are input mode.
PINS
nBUSY
PE
SLCT
nFAULT
nBUSY
PE
SLCT
nFAULT
PCI + 1284 Printer Port
DATA Bits
Bit-7
Bit-6
Bit-5
Bit-4
Bit-3
Bit-2
Bit-1
Bit-0
Nm9805
Page 11