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Chapter 2
Digital I/O
Figure 2-16 illustrates the difference between line and bus filtering.
Figure 2-16.
Line and Bus Filtering
Connecting Digital I/O Signals
The DIO signals, P0.<0..31> and P1.<0..7> are referenced to D GND. Each line can be
individually programmed as an input or output. Figure 2-17 shows P1.<0..3> configured for
digital input and P1.<4..7> configured for digital output. Digital input applications include
receiving TTL signals and sensing external device states, such as the state of the switch shown
in the figure. Digital output applications include sending TTL signals and driving external
devices, such as the LED shown in the figure.
2A With line filtering, filtered input A would ignore the glitch on digital input P0.B and transition after two filter
clocks.
3A Filtered input A goes high when sampled high for two consecutive filter clocks and transitions on the next
filter edge because digital input P0.B glitches.
Digit
a
l Inp
u
t P0.A
Digit
a
l Inp
u
t P0.B
Filter Clock
Filtered Inp
u
t A
Filtered Inp
u
t B
1A
2A
3
A
