
W83977ATF
PRELIMINARY
Publication Release Date:April 1998
-
54
-
Revision 0.52
Bit 1:
ETBREI - Enable TBR (Transmitter Buffer Register) Empty Interrupt
A write to 1 will enable the transmitter buffer register empty interrupt.
ERBRI - Enable RBR (Receiver Buffer Register) Interrupt
A write to 1 will enable receiver buffer register interrupt.
Bit 0:
4.2.3 Set0.Reg2 - Interrupt Status Register/IR FIFO Control Register (ISR/UFR)
Interrupt Status Register (Read Only)
Mode
Legacy IR
Advanced
IR
Reset Value
B7
B6
B5
0
B4
0
B3
IID2
HS_I
B2
IID1
USR_I/
FEND_I
0
B1
IID0
B0
IP
FIFO Enable FIFO Enable
TMR_I
FSF_I
TXTH_I DMA_I
TXEMP_I RXTH_I
0
0
1
0
0
1
0
Legacy IR:
This register reflects the Legacy IR interrupt status, which is encoded by different interrupt sources
into 3 bits.
Bit 7, 6: These two bits are set to a logical 1 when UFR bit 0 = 1.
Bit 5, 4: These two bits are always logical 0.
Bit 3: When not in FIFO mode, this bit is always 0. In FIFO mode, both bit 3 and 2 are set to logical
1 when a time-out interrupt is pending.
Bit 2, 1: These bits identify the priority level of the pending interrupt, as shown in the table below.
Bit 0: This bit is a logical 1 if there is no interrupt pending. If one of the interrupt sources has
occurred, this bit will be set to logical 0.
TABLE: INTERRUPT CONTROL FUNCTION
ISR
INTERRUPT SET AND FUNCTION
Bit
3
Bit
2
Bit
1
Bit
0
Interrupt
priority
Interrupt Type
Interrupt Source
Clear Interrupt
0
0
0
1
0
1
1
0
-
-
No Interrupt pending
1. OER = 1 2. PBER =1
3. NSER = 1 4. SBD = 1
1. RBR data ready
2. FIFO interrupt active level
reached
Data present in RX FIFO for 4
characters period of time since last
access of RX FIFO.
TBR empty
-
First
IR Receive Status
Read USR
0
1
0
0
Second
RBR Data Ready
1. Read RBR
2. Read RBR until FIFO
data under active level
Read RBR
1
1
0
0
Second
FIFO Data Time-out
0
0
1
0
Third
TBR Empty
1. Write data into TBR
2. Read ISR (if priority is
third)
** Bit 3 of ISR is enabled when bit 0 of UFR is a logical 1.
Advanced IR: