451 interrupt identification register decode, Table 451, “interrupt identification, Uarts—intel – Intel CONTROLLERS 413808 User Manual
Page 673: Non prioritized interrupts, Intel
Intel
®
413808 and 413812 I/O Controllers in TPER Mode
October 2007
Developer’s Manual
Order Number: 317805-001US
673
UARTs—Intel
®
413808 and 413812
Table 451. Interrupt Identification Register Decode
Interrupt ID bits
Interrupt SET/RESET Function
3 2 1 0 Priority
Type
Source
RESET Control
IP#
0
0
0
1
-
None
No Interrupt is pending.
-
IID[11]
0
1
1
0
Highest
Receiver Line
Status
Overrun Error, Parity Error,
Framing Error, Break
Interrupt.
Reading the Line Status
Register.
IID[10]
0
1
0
0
Second
Highest
Received Data
Available.
Non-FIFO mode: Receive
Buffer is full.
Non-FIFO mode: Reading the
Receiver Buffer Register.
FIFO mode: Trigger level
was reached.
FIFO mode: Reading bytes until
Receiver FIFO drops below
trigger level or setting
RESETRF bit in FCR register.
TOD
1
1
0
0
Second
Highest
Character
Timeout
indication.
FIFO Mode only: At least 1
character is in receiver FIFO
and there was no activity for
a time period.
Reading the Receiver FIFO or
setting RESETRF bit in FCR
register.
IID[01]
0
0
1
0
Third
Highest
Transmit FIFO
Data Request
Non-FIFO mode: Transmit
Holding Register Empty
Reading the IIR Register (when
the source of the interrupt) or
writing into the Transmit
Holding Register.
FIFO mode: Transmit FIFO
has half or less than half
data.
Reading the IIR Register (when
the source of the interrupt) or
writing to the Transmitter FIFO.
IID[00]
0
0
0
0
Fourth
Highest
Modem Status
Clear to Send, Data Set
Ready, Ring Indicator,
Received Line Signal Detect
Reading the Modem Status
Register.
Non Prioritized Interrupts
ABL
4
None
Autobaud Lock
Indication
Autobaud circuitry has
locked onto the baud rate.
Reading the IIR Register