Mask Option - Epson E0C6001 Technical Manual

E0C6001 TECHNICAL HARDWARE

Mask option

I-22
Consequently, when the input terminal is in the active
status (high status), do not rewrite the mask register (clear-
ing, then setting the mask register), so that a factor flag will
only set at the rising 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 (low status).
The contents that can be selected with the input port mask
option are as follows:
(1) An internal pull-down resistance can be selected for each
of the four bits of the input ports (K00–K03). Having
selected "pull-down resistance disabled", take care that
the input does not float. Select "pull-down resistance
enabled" for input ports that are not being used.
(2) The input interrupt circuit contains a noise rejection
circuit to prevent interrupts form occurring through
noise. The mask option enables selection of the noise
rejection circuit for each separate pin series. When "use"
is selected, a maximum delay of 0.5 ms (fosc = 32 kHz)
occurs from the time an interrupt condition is established
until the interrupt factor flag (IK) is set to 1.