PIN #
BUFFER
TYPE
NAME
SYMBOL
DESCRIPTION
TQFP
QFP
82,84
84,86
nRing
nRI1
I
Active low Ring Indicator inputs for the serial port.
Handshake signal which notifies the UART that the
telephone ring signal is detected by the modem. The
CPU can monitor the status of nRI signal by reading
bit 6 of Modem Status Register (MSR). A nRI signal
state change from low to high after the last MSR read
will set MSR bit 2 to a 1. If bit 3 of Interrupt Enable
Register is set, the interrupt is generated when nRI
(Note1)
Indicator
nRI2
changes state.
Note:
Bit 6 of MSR is the
complement of nRI.
PARALLEL PORT INTERFACE (NOTE 2)
nPrinter
nSLCTIN
This active low output selects the printer. This is the
complement of bit 3 of the Printer Control Register.
Refer to Parallel Port description for use of this pin in
ECP and EPP mode.
71
72
74
73
74
76
(OD14/OP1
Select Input
4)/OD12
(Note2)
nInitiate
Output
(Note2)
nINIT
(OD14/OP1 This output is bit 2 of the printer control register. This
4)/OD12
is used to initiate the printer when low.
Refer to Parallel Port description for use of this pin in
ECP and EPP mode.
nAutofeed
Output
nAUTOFD
This output goes low to cause the printer to
automatically feed one line after each line is printed.
The nAUTOFD output is the complement of bit 1 of
the Printer Control Register.
(OD14/OP1
4)/OD12
(Note2)
Refer to Parallel Port description for use of this pin in
ECP and EPP mode.
nStrobe
Output
(Note2)
nSTROBE
BUSY
An active low pulse on this output is used to strobe
the printer data into the printer. The nSTROBE
output is the complement of bit 0 of the Printer Control
Register.
75
59
77
61
(OD14/OP1
4)/OD12
Refer to Parallel Port description for use of this pin in
ECP and EPP mode.
This is a status output from the printer, a high
indicating that the printer is not ready to receive new
data. Bit 7 of the Printer Status Register is the
complement of the BUSY input. Refer to Parallel Port
description for use of this pin in ECP and EPP mode.
Busy
I/OD12
nACK
PE
A low active output from the printer indicating that it
has received the data and is ready to accept new
data. Bit 6 of the Printer Status Register reads the
nACK input. Refer to Parallel Port description for use
of this pin in ECP and EPP mode.
60
58
62
60
nAcknowl-
edge
I/OD12
I/OD12
Another status output from the printer, a high
indicating that the printer is out of paper. Bit 5 of the
Printer Status Register reads the PE input. Refer to
Parallel Port description for use of this pin in ECP and
EPP mode.
Paper End
SMSC DS – SP37E760
Page 10
Rev. 04/13/2001
SMSC [ SMSC CORPORATION ]
