Specifications

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PC/II+p Board Technical Reference Manual 67

7.23.2 Serial COM2 Pinout

Table 35 Signals – J904 – Serial COM2 Interface

PIN NAME PIN# SIGNAL NAME SIGNAL DESCRIPTION

C2-CTS#

c15 Clear to Send This active low input is the handshake signal which notifies the

UART that the modem is ready to receive data. The CPU can

monitor the status of C2-CTS# signal by reading bit 4 of Modem

Status Register (MSR). A C2-CTS# signal state change from low

to high after the last MSR read will set MSR bit 0 to a 1. If bit 3 of

Interrupt Enable Register is set, the interrupt is generated when

C2-CTS# changes state. The C2-CTS# signal has no effect on

the transmitter. Note : Bit 4 of MSR is the complement of C2-

CTS#.

C2-DCD#

c14 Data Carrier

Detect

This active low input is a handshake signal which notifies the

UART that carrier signal is detected by the modem. The CPU

can monitor the status of the C2-DCD# signal by reading bit 7 of

Modem Status Register (MSR). A C2-DCD# signal state change

from low to high after the last MSR read will set MSR bit 3 to a 1.

If bit 3 of Interrupt Enable Register is set, the interrupt is

generated when the C2-DCD# input changes state. Note : bit 7

of MSR is the complement of C2-DCD#.

C2-DSR#

b14 Data Set Ready This active low input is the handshake signal which notifies the

UART that the modem is ready to establish the communication

link. The CPU can monitor the status of the C2-DSR# signal by

reading bit5 of Modem Status Register (MSR). A C2-DSR#

signal state change from low to high after the last MSR read will

set MSR bit 1 to a 1. If bit 3 of Interrupt Enable Register is set,

the interrupt is generated when C2-DSR# changes state. Note:

Bit 5 of MSR is the complement of C2-DSR#.

C2-DTR#

b15 Data Terminal

Ready

This active low output is the handshake output signal that

signifies to modem that the UART is ready to establish data

communication link. This signal can be programmed by writing to

bit 0 of Modem Control Register (MCR).

C2-RI#

a15 Ring Indicator This active low input is the handshake signal which notifies the

UART that the telephone ring signal is detected by the modem.

The CPU can monitor the status of the C2-RI# signal by reading

bit 6 of Modem Status Register (MSR). A C2-RI# 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 the C2-RI# input changes state. Note : bit 6 of

MSR is the complement of C2-RI#.

C2-RTS#

e15 Request to Send This Active low output is the handshake output signal that

notifies the modem that the UART is ready to transmit data. This

signal can be programmed by writing to bit 1 of Modem Control

signal to inactive mode (high).

C2-RXD

a14 Receive Data Receive data serial input line.

C2-TXD

d15 Transmit Data Transmit data serial output line.