SC16C754B NXP Semiconductors, SC16C754B Datasheet - Page 30

• Manufacturer Part Number: SC16C754B
• Description: 5 V - 3.3 V and 2.5 V quad UART - 5 Mbit/s (max.)
• Manufacturer: NXP Semiconductors

NXP Semiconductors
SC16C754B_4
Product data sheet
7.9 Interrupt Identification Register (IIR)
The IIR is a read-only 8-bit register which provides the source of the interrupt in a
prioritized manner.
Table 17.
The interrupt priority list is shown in
Table 18.
Bit
7:6
5
4
3:1
0
Priority
level
1
2
2
3
4
5
6
Symbol
IIR[7:6]
IIR[5]
IIR[4]
IIR[3:1]
IIR[0]
IIR[5]
0
0
0
0
0
0
1
Interrupt identification register bits description
Interrupt priority list
IIR[4]
0
0
0
0
0
1
0
Description
Mirror the contents of FCR[0].
RTS/CTS LOW-to-HIGH change of state.
1 = Xoff/special character has been detected.
3-bit encoded interrupt. See
Interrupt status.
5 V, 3.3 V and 2.5 V quad UART, 5 Mbit/s (max.) with 64-byte FIFOs
Table 17
logic 0 = an interrupt is pending
logic 1 = no interrupt is pending
Rev. 04 — 6 October 2008
IIR[3]
0
1
0
0
0
0
0
shows interrupt identification register bit settings.
1
1
1
0
0
0
0
IIR[2]
Table
18.
IIR[1]
1
0
0
1
0
0
0
Table
18.
IIR[0]
0
0
0
0
0
0
0
Source of the interrupt
Receiver line status error
Receiver time-out interrupt
RHR interrupt
THR interrupt
Modem interrupt
Received Xoff signal/
special character
CTS, RTS change of state from
active (LOW) to inactive (HIGH)
SC16C754B
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