Hardware description
Figure 15: I/O expander schematic
Note:
Software debouncing is not needed when using the I/O expander. Each button on the nRF52
DK is equipped with a debouncing filter.
4.6 32.768 kHz crystal
can use an optional 32.768 kHz crystal (
X2
) for higher accuracy and lower average
power consumption.
On the nRF52 DK,
P0.00
and
P0.01
are used for the 32.768 kHz crystal by default and are not available as
on the connectors.
Note:
When using ANT/ANT+, the 32.768 kHz crystal (
X2
) is required for correct operation.
If
P0.00
and
P0.01
are needed as normal I/Os, then the 32.768 kHz crystal can be disconnected and the
GPIO routed to the connectors. Cut the shorting track on
SB1
and
SB2
, and solder
SB3
and
SB4
. See the
following figure for reference.
Figure 16: Configuring
P0.00
and
P0.01
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