Intel 386 - Manual (Page 295)

Intel386™ EX EMBEDDED MICROPROCESSOR USER’S MANUAL
11-8
Figure 11-4. SIO n Data Transmission Process Flow
A2527-02
Select the BCLKIN source and
the transmitter input baud rate.
Select the data frame. (Word length, number
of stop bits, and type of parity.) Enable interrupts
and/or DMA.
Is
transmit buffer
empty?
Write data to transmit buffer register.
(ISR or DMA cycle)
Transmitter shifts data frame onto
the TXD
n pin. Data is transmitted
least-significant bit first.
Transmitter transfers data to shift register
and sets transmit buffer empty flag, causing
an interrupt or DMA request.
End
Yes
No
Transmitter shifts out last stop bit
then sets the transmitter empty flag.
More
Data to
Transmit
?
No
Yes