12
12-6
Serial I/O
12.2 Serial I/O Related Registers
32180 Group User's Manual (Rev.1.0)
12.2.1 SIO Interrupt Related Registers
The SIO interrupt related registers are used to control the interrupt request signals output from SIO to the
Interrupt Controller (ICU), as well as select the source of each interrupt request.
(1) Interrupt request status bit
This status bit is used to determine whether an interrupt is requested. When an interrupt request occurs, this
bit is set in hardware (cannot be set in software). The status bit is cleared by writing "0". Writing "1" has no
effect; the bit retains the status it had before the write. Because this bit is unaffected by the interrupt request
enable bit, it can also be used to inspect the operating status of peripheral functions.
In interrupt handling, make sure that within the grouped interrupt request status, only the status bit for the
interrupt request that has been serviced is cleared. If the status bit for any interrupt request that has not been
serviced is cleared, the pending interrupt request is cleared simultaneously with its status bit.
(2) Interrupt request enable bit
This bit is used to disable unnecessary interrupt requests within the grouped interrupt request. Set this bit to
"1" to enable interrupt requests or "0" to disable interrupt requests.
Figure 12.2.1 Interrupt Request Status and Enable Registers
To the Interrupt Controller
Interrupt request from
each peripheral function
Interrupt request status
Data bus
Set
•
Group interrupt
Interrupt request enable
clear
F/F
F/F
Data=0
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