
MFC2000 Multifunctional Peripheral Controller 2000
Hardware Description
17-6
Conexant
100723A
Parallel Port Interface Register
The Parallel Port Interface Register is a read/write register that contains eleven bits to control the parallel port
interface signals. Four read-only bits are used to read the logic level of host input pins, two read-only bits are
used to read the logic level on the BUSY and ACKn printer output pins, and five read/write bits control the logic
levels on the printer output pins. When hardware handshaking is enabled(mode 1,2,3) BUSY and ACKn are
controlled by the PPI state machine. When hardware handshaking is disabled (mode 0) and the PPI state
machine is idle BUSY and ACKn may be controlled by the software using the FBSY and FACK bits.
Note:
NFLT,SEL,PERR and FBSY are arranged as register bits 0, 1, 2, and 3, respectively, to
correspond to their use as parallel data lines during nibble mode reverse data transfers.
Address
Bit 15
(Not Used)
Bit 14
FRDA
Bit 13
SPER
(R)
Bit 12
SSEL
(R)
Bit 11
SNFL
(R)
Bit 10
NINI
(R)
Bit 9
Bit 8
Default
Rst. Value
x0000000b
Read Value
07h
Parallel Port
Interface Reg.
(PIOIF)
$01FF8203
NAFD
(R)
NSTR
(R)
Address
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Default
Rst. Value
08h
Read Value
08h
Parallel Port
Interface Reg.
(PIOIF)
$01FF8202
NSIN
(R)
NACK
(R)
BUSY
(R)
FACK
FBSY
PERR
SEL
NFLT
NFLT
FAULTn
This bit controls the logic level driven on FAULTn output pin. Setting
NFLT drives a high level and clearing SEL drives a low level.
This controls the logic level driven on the SLCTOUT output pin.
Setting SEL drives a high level and clearing SEL drives a low level.
This bit controls the logic level driven on the PE output pin. Setting
PERR drives a high level and clearing PERR drives a low level.
This bit force a high level to be driven on the BUSY output pin.
Normally this is done when hardware handshaking is disabled(mode
0), and the PPI state machine is idle. The FBSY bit is OR’ed with the
BUSY output from the PPI state machine before driving the BUSY
output pin. IF FBSY is set, then the BUSY output pin is forced high,
and the BUSY bit is read high. This bit is set on reset.
This bit forces a low level to be driven on the ACKn output pin.
Normally this is done when hardware handshaking is disabled (mode
0), and the PPI state machine is idle. The FACK bit is NOR’ed with the
ACKn output from the PPI state machine before driving the ACKn
output pin. If FACK is set, then the ACKn output pin is forced low, and
the NACK bit is to be read low.
This status bit indicates the level driven on the BUSY output pin. This
bit is the FBSY bit OR’ed with BUSY output from the PPI state
machine. Since FBSY is set on reset, this bit will appear set on reset.
This is a read-only status bit.
SEL
SLCTOUT
PERR
Paper Error
FBSY
Force Busy
FACK
Force Ack
BUSY