S1C62N33 TECHNICAL HARDWARE
EPSON
I-33
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Input Ports)
When using an input interrupt, if you rewrite the content
of the mask register, when the value of the input terminal
which becomes the interrupt input is in the active status,
the factor flag for input interrupt may be set. Therefore,
when using the input interrupt, the active status of the
input terminal implies
input terminal = low status, when the falling edge
interrupt is effected and
input terminal = high status, when the rising edge
interrupt is effected.
When an interrupt is triggered at the falling edge of an
input terminal, a factor flag is set with the timing of
shown in Figure 4.4.4. However, when clearing the con-
tent of the mask register with the input terminal kept in
the low status and then setting it, the factor flag of the
input interrupt is again set at the timing that has been
set. Consequently, when the input terminal is in the
active status (low status), do not rewrite the mask regis-
ter (clearing, then setting the mask register), so that a
factor flag will only set at the falling edge in this case.
When clearing, then setting the mask register, set the
mask register, when the input terminal is not in the
active status (high status).
When an interrupt is triggered at the rising edge of the
input terminal, a factor flag will be set at the timing of
shown in Figure 4.4.4. In this case, when the mask
registers cleared, then set, you should set the mask
register, when the input terminal is in the low status.
In addition, when the mask register = "1" and the content
of the differential register is rewritten in the input termi-
nal active status, an input interrupt factor flag may be
set. Thus, you should rewrite the content of the differen-
tial register in the mask register = "0" status.
(4) Read-out the interrupt factor flag (IK) only in the DI
status (interrupt flag = "0"). Read-out during EI status
will cause malfunction.
(5) Writing to the interrupt mask registers (EIK) can be done
only in the DI status (interrupt flag = "0").
Writing during EI status will cause malfunction.