W90221X Winbond Electronics Corp America, W90221X Datasheet - Page 161

• Manufacturer Part Number: W90221X
• Description: Pa-risc Embedded Controller
• Manufacturer: Winbond Electronics Corp America

Bit 3 DMA mode select
bit-3 is always 0.
Bit 4-6 Interrupt Identification bits
COM port
Bit 7 No Interrupt (NOI) pended
W90221X version 0.6
The DMA function is not implemented in this version. Reading IIR, the
The IID[0:2] along with NOI indicate current interrupt request from
Table 6.7-3 : Interrupt Control Functions
- - - 1
IIR[4:7]
0 1 1 0
0 1 0 0
1 1 0 0
0 0 1 0
0 0 0 0
Highest
Second
Second
Priority
Fourth
Third
--
Receiver
Line Status
(Irpt_RLS)
Received
Data
Available
(Irpt_RDA)
Receiver
FIFO Time-
out
(Irpt_TOUT)
Transmitter
Hoding
Register
Empty
(Irpt_THRE)
MODEM
Status
(Irpt_MOS)
Interrupt
None
Type
Overrun Error or
Parity Error or
Framing Error or
Break Interrupt
Receiver FIFO
thres-hold level
is reached
Receiver FIFO is
non-empty and
no activities are
occured in
receiver FIFO
during the TOR
defined time
duration
Transmitter
Holding Register
Empty
CTS, DSR, DCD
bits chang state
or RI bit
changes from
high to low
Interrupt Source
None
Reading the
LSR
Receiver FIFO
drops below the
threshold level
Reading the
RBR
Reading the IIR
(if source of
interrupt is
Irpt_THRE) or
writing into the
THR
Reading the
MSR
Interrupt Reset
control
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