sc16c752 NXP Semiconductors, sc16c752 Datasheet - Page 25

• Manufacturer Part Number: sc16c752
• Description: Dual Uart With 64-byte Fifo
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 11635
Product data
7.7 Modem status register (MSR)
7.8 Interrupt enable register (IER)
This 8-bit register provides information about the current state of the control lines
from the mode, data set, or peripheral device to the processor. It also indicates when
a control input from the modem changes state.
register bit settings per channel.
Table 15:
[1]
The interrupt enable register (IER) enables each of the six types of interrupt, receiver
error, RHR interrupt, THR interrupt, Xoff received, or CTS/RTS change of state from
LOW to HIGH. The INT output signal is activated in response to interrupt generation.
Table 16
Table 16:
Bit
7
6
5
4
3
2
1
0
Bit
7
6
5
The primary inputs RI, CD, CTS, DSR are all Active-LOW, but their registered equivalents in the MSR
and MCR (in loop-back) registers are Active-HIGH.
Symbol
IER[7]
IER[6]
IER[5]
Symbol
MSR[7]
MSR[6]
MSR[5]
MSR[4]
MSR[3]
MSR[2]
MSR[1]
MSR[0]
shows interrupt enable register bit settings.
Modem Status Register bits description
Interrupt Enable Register bits description
[1]
[1]
[1]
Description
CTS interrupt enable.
RTS interrupt enable.
Xoff interrupt.
Rev. 04 — 20 June 2003
Description
CD (Active-HIGH, logical 1). This bit is the complement of the CD input
during normal mode. During internal loop-back mode, it is equivalent to
MCR[3].
RI (Active-HIGH, logical 1). This bit is the complement of the RI input
during normal mode. During internal loop-back mode, it is equivalent to
MCR[2].
DSR (Active-HIGH, logical 1). This bit is the complement of the DSR
input during normal mode. During internal loop-back mode, it is
equivalent MCR[0].
CTS (Active-HIGH, logical 1). This bit is the complement of the CTS
input during normal mode. During internal loop-back mode, it is
equivalent to MCR[1].
changed state. Cleared on a read.
state from LOW to HIGH. Cleared on a read.
changed state. Cleared on a read.
changed state. Cleared on a read.
Logic 0 = Disable the CTS interrupt (normal default condition).
Logic 1 = Enable the CTS interrupt.
Logic 0 = Disable the RTS interrupt (normal default condition).
Logic 1 = Enable the RTS interrupt.
Logic 0 = Disable the Xoff interrupt (normal default condition).
Logic 1 = Enable the Xoff interrupt.
CD. Indicates that CD input (or MCR[3] in loop-back mode) has
RI. Indicates that RI input (or MCR[2] in loop-back mode) has changed
DSR. Indicates that DSR input (or MCR[0] in loop-back mode) has
CTS. Indicates that CTS input (or MCR[1] in loop-back mode) has
Table 15
Dual UART with 64-byte FIFO
© Koninklijke Philips Electronics N.V. 2003. All rights reserved.
shows modem status
SC16C752
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