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nRF51822 Development Kit User Guide v1.4
5.1.7
32.768 kHz crystal
The nRF51822 can use an optional 32.768 kHz crystal (X2) for higher accuracy and lower average power
consumption. On the nRF51822 DK module, P0.26 and P0.27 are disconnected from the Motherboard and
connected to the two jumpers on the nRF51822 DK module at the position 32 kHz on connector
P4
(Pin 1
and Pin 3 for XL1 and Pin 2 and Pin 4 for XL2). This is the default position of the jumpers when shipped.
Note:
The 32.768 kHz crystal has to be selected for the
Bluetooth
examples to work.
If the jumpers are placed in the position I/O on connector
P4
(Pin 3 and Pin 5 for XL1 and Pin 4 and Pin 6 for
XL2), P0.26 and P0.27 connects to the Motherboard and can be used for normal I/O.
Figure 15
32.768 kHz crystal circuit schematic and PCB
1
2
3
4
5
6
P4
Pin Header 2x3 SMD
C14
12pF
C13
12pF
P0.26
P0.27
R8
0R
R7
0R
AIN0
AIN1
XL1
XL2
X2
32.768kHz