Digi NS9210, Hardware Reference Manual

Page: 73 / 80

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R e s e t a n d e d g e s e n s i t i v e i n p u t t i m i n g r e q u i r e m e n t s
The critical timing requirement is the rise and fall time of the input. If the rise time
is too slow for the reset input, the hardware strapping options may be registered
incorrectly. If the rise time of a positive-edge-triggered external interrupt is too
slow, then an interrupt may be detected on both the rising and falling edge of the
input signal.
A maximum rise and fall time must be met to ensure that reset and edge sensitive
inputs are handled correctly. With Digi processors, the maximum is 500 nanoseconds
as shown:
On the NS9210 Processor Module JumpStart there was a measurement of 220ns rise
time and 10ns fall time.
negative edge input
t
F
max = 500nsec
V
IN
= 2.0V to 0.8V
t
F
reset_n or positive edge input
t
R
max = 500nsec
V
IN
= 0.8V to 2.0V
t
R