SIC63616-(Rev. 1.0) NO. P50
3240-0412
The interrupt select registers (SIP00–SIP03, SIP10–SIP13) and interrupt polarity select registers (PCP00–
PCP03, PCP10–PCP13) are individually provided for the I/O ports P10–P13 and P40–P43.
The interrupt select registers (SIPxx) select the ports to be used for generating interrupts or canceling SLEEP
mode. Writing "1" to an interrupt select register incorporates that port into the interrupt generation condi-
tions. Changing the port where the interrupt select register has been set to "0" does not affect the generation
of the interrupt.
The input interrupt timing can be selected using the interrupt polarity select registers (PCPxx) so that an
interrupt will be generated at the rising edge or falling edge of the input.
By setting these two conditions, an interrupt request signal and a SLEEP cancellation signal are generated
at the rising or falling edge (selected by PCPxx) of the signal input to the port (selected by SIPxx).
When an interrupt factor occurs, the interrupt factor flag (IK00–IK03, IK10–IK13) is set to "1". At the same
time, an interrupt request is generated to the CPU if the corresponding interrupt mask register (EIK00–
EIK03, EIK10–EIK13) is set to "1".
When the interrupt mask register (EIKxx) is set to "0", the interrupt request is masked and no interrupt is
generated to the CPU. However, SLEEP mode can be cancelled regardless of the interrupt mask register set-
ting.
The key input interrupt circuit has a noise rejector to avoid unnecessary interrupt generation due to noise
or chattering. This noise rejector allows selection of a noise-reject frequency from among three types shown
in Table 4.5.7.1. Use the NRSP01 and NRSP00 registers for P10–P13 ports or NRSP11 and NRSP10 registers
for P40–P43 ports to select a noise-reject frequency. If a pulse shorter than the selected width is input to the
port, an interrupt is not generated. When high speed response is required, turns the noise rejecter off (by-
passed).
Table 4.5.7.1 Setting up noise rejector
NRSP01
NRSP11
1
1
0
0
Noise reject frequency
f
OSC1
/ 256 (128 Hz)
f
OSC1
/ 64 (512 Hz)
f
OSC1
/ 16 (2 kHz)
OFF
(bypassed)
NRSP00
NRSP10
1
0
1
0
Reject pulse width
7.8 msec
2.0 msec
0.5 msec
–
Notes: • Be sure to turn the noise rejector off before executing the SLP instruction.
• Reactivating from SLEEP status can only be done by generation of a key input interrupt factor.
Therefore when using the SLEEP function, it is necessary to set the interrupt select register (SIPxx
= "1") of the port to be used for releasing SLEEP status before executing the SLP instruction.
Furthermore, enable the key input interrupt using the corresponding interrupt mask register (EIKxx
= "1") before executing the SLP instruction to run key input interrupt handler routine after SLEEP
status is released.