Intel 386

13-13
SYNCHRONOUS SERIAL I/O UNIT
The SSIO Unit can be operated either by using a polling method or through interrupts.
• Figure 13-12 shows a basic flowchart for using the polling method to receive data through
the SSIO.
• Figure 13-13 shows a basic flowchart for the Interrupt Service Routine necessary when
using interrupts to receive data through the SSIO. If interrupts are used, follow the below
sequence for initialization:
1. Initialize the SSIO.
2. Initialize the interrupts - ICU initialization, Interrupt Service Routine, etc.
3. Unmask the interrupts on the ICU.
Figure 13-12. Receive Data by Polling
A3396-01
ROE=0
?
Yes
Error
Routine
Initialize SSIO
RHBF=1
?
Read Data
(SSIORBUF)
No
No
Yes