
I-102
EPSON
S1C62N33 TECHNICAL HARDWARE
CHAPTER 5: SUMMARY OF NOTES
(2) When "noise rejector circuit enable" is selected with the
mask option, a maximum delay of 1 ms occurs from the
interrupt factor flag (IK) is set to "1" (until the interrupt is
actually generated). Hence, pay attention to the timing
when reading out (resetting) the interrupt factor flag. For
example, immediately after performing a key scan with
the key matrix, the flag will not be reset because the
delay in the interrupt factor flag read-out means the flag
is set after read-out. (The key scan changes the input
status and the interrupt factor flag is set, necessitating
read-out to reset the flag.)
(3) Input interrupt programing related precautions
When the content of the mask register is rewritten, while the port K
input is in the active status. The input interrupt factor flags are set
at and , being the interrupt due to the falling edge and the
interrupt due to the rising edge.
Port K input
Factor flag set Not set
Factor flag set
Differential register
Mask register
Active status
Rising edge interrupt
Falling edge interrupt
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 5.2.1. 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.
Fig. 5.2.1
Input interrupt timing