2 edge detection on pin p20 – NEC PD78214 User Manual
Page 325
296
µ
PD78214 Sub-Series
11.2 EDGE DETECTION ON PIN P20
An edge on pin P20 is detected after noise elimination by means of analog delay. A pulse width of at least 10
µs
is required to detect the edge.
Fig. 11-3 Edge Detection on Pin P20
Caution Because noise elimination by analog delay is performed by pin P20, an edge is detected up to 10
µs after it is actually input. This
pin differs from pins P21 to P26 in that the delay depends on the characteristics of the device.
10 s
(Max.)
µ
10 s
(Max.)
µ
10 s (Min.)
µ
Rejected as noise
because pulse is
too narrow
Falling edge is detected
because pulse is sufficiently wide.
Rising edge is detected
because pulse is sufficiently wide.
Rejected as noise
because pulse is
too narrow
P20 input
P20 after noise rejection
Rising edge
detection signal
Falling edge
detection signal