nRF52840 Preview DK v0.9.x

32.768 kHz crystal

The nRF52840 SoC can use an optional 32.768 kHz crystal (X2) for higher accuracy and lower average power consumption.

On the nRF52840 Preview DK board, P0.00 and P0.01 are by default used for the 32.768 kHz crystal and are not available as GPIO on the connectors.
Important: 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, 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 figure below for reference.
Figure 1. Configuring P0.00 and P0.01

Figure 2. 32.768 kHz crystal and SB1–SB4 schematic