PC87307VUL National Semiconductor, PC87307VUL Datasheet - Page 20

• Manufacturer Part Number: PC87307VUL
• Description: PC87307/PC97307 Plug and Play Compatible and PC97 Compliant SuperI/O
• Manufacturer: National Semiconductor

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POR
RD
RDATA
RI2,1
RING
RTS2,1
SELCS
SIN2,1
SLCT
SLIN
Signal/Pin
Name
159
33
95
145, 135
69 or 160
146, 136
77
147, 137
114
118
Number
Pin
UART1, APC
Configuration
Parallel Port
Parallel Port
ISA-Bus
UART1,
UART1,
Module
UART2
UART2
APC
FDC
APC
Signal/Pin Connection and Description
Group 21
Group 17
Group 13
Group #
Group 1
Group 1
Group 7
Group 7
Group 4
Group 1
Group 2
I/O and
Output
Output
Input
Input
Input
Input
Input
Input
Input
I/O
Power Off Request – This signal becomes active when an APC
Switch Off event occurs, regardless of the fail-safe delay. Selection of
edge or level for POR is via the APCR1 register of the APC.
Selection of an output buffer is via GPIO22 output buffer control bits
(in the Port 2 Output Type and Port 2 Pull-up Control registers
described in Table 8-1 on page 170). See Section 4.3 on page 55.
This signal is multiplexed with GPIO22.
I/O Read – An active low RD input signal indicates that the
microprocessor has read data.
Read Data – This input signal holds raw serial data read from the
Floppy Disk Drive (FDD).
Ring Indicators (Modem) – When low, this signal indicates that a
telephone ring signal has been received by the modem.
The CPU can test the status of the RI modem status input signal by
reading bit 6 (RI) of the Modem Status Register (MSR) for the
appropriate serial channel. Bit 6 is the complement of the RI signal.
Bit 2 (TERI) of the MSR indicates whether the RI input signal has
changed from low to high since the previous reading of the MSR.
When the TERI bit of the MSR is set, an interrupt is generated if
modem status interrupts are enabled.
When enabled, a high to low transition on RI1 or RI2 activates the
ONCTL pin. The RI1 and RI2 pins each have an schmitt-trigger input
buffer.
Ring Indicator (APC) – Detection of an active low RING pulse or
pulse train activates the ONCTL signal. The APC’s APCR2 register
determines which pin the RING signal uses. The pins have a schmitt-
trigger input buffer.
RING is multiplexed on pin 69 with XDCS and on pin 160 with
GPIO23.
Request to Send – When low, these output signals indicate to the
modem or other data transfer device that the corresponding UART1
or UART2 is ready to exchange data.
The RTS signal can be set active low by programming bit 1 (RTS) of
the Modem Control Register (MCR) to a high level. A Master Reset
(MR) sets RTS to inactive high. Loopback operation holds it inactive.
RTS2 is multiplexed with CFG2. RTS1 is multiplexed with BADDR1.
Select CSOUT – During reset, this signal is sampled into bit 1 of the
SuperI/O Configuration 1 register (index 21h).
A 40 K
resistor for National Semiconductor testing) controls this pin during
reset. Do not pull this signal low during reset.
This signal is multiplexed with GPIO21, IRSL2 and XD6.
Serial Input – This input signal receives composite serial data from
the communications link (peripheral device, modem or other data
transfer device.)
Select – This input signal is set active high by the printer when the
printer is selected. This pin is internally connected to a nominal
25 K
Select Input – When this signal is active low it selects the printer.
This signal is in TRI-STATE after a 0 is loaded into the corresponding
control register bit.
An external 4.7 K
This signal is multiplexed with ASTRB.
pull-down resistor.
20
internal pull-up resistor (or a 10 K
pull-up resistor should be used.
Function
external pull-down