Intel 386

11-11
ASYNCHRONOUS SERIAL I/O UNIT
Figure 11-6. SIO n Data Reception Process Flow

A2525-02
Select the BCLKIN source and
the receiver input baud rate.
Select the data frame. (Word length,
number of stop bits, and type of
parity.) Enable interrupts and/or DMA.
Receiver shifts data into shift register
from the RXD
n pin.
Was 
a break condition
detected?
Was
a framing error
detected?
Was
a parity error
detected?
Receiver sets the
parity error flag.
Receiver sets
the break
interrupt flag.
Is
receive
buffer full flag
set?
Receiver transfers
data to receive
buffer and sets
overrun error flag.
Receiver transfers data to receive
buffer and sets receive buffer full
flag.
End
Receiver sets
the framing 
error flag.
No
No
No
Yes Yes Yes
Yes
No
Service error
interrupt
(if enabled)
Service error
interrupt
(if enabled)
Any
error flags
set?
No
Yes