The PIC18F56Q24 Curiosity Nano Board has a 32.768 kHz crystal footprint for standard
3.2 mm by 1.5 mm surface mount crystals with two terminals. The crystal footprint is not
connected to the PIC18F56Q24 by default, as the GPIOs are routed to the edge
connector.Figure 4-1. 32.768 kHz Crystal Block
Diagram
Some hardware modifications are required to use a crystal with the PIC18F56Q24.
The two I/O lines routed to the edge
connector must be disconnected to reduce the chance of contention to the crystal and to
remove excessive capacitance on the lines
Disconnect the edge connector by cutting
the two cut straps on the bottom side of the board, J107 and J108. Marked RA6 and RA7 in
the silkscreen
Connect the crystal by soldering on a
solder blob on each circular solder point next to the crystal on the top side of the
board, J109 and J110
Add suitable capacitors to C104 and
C105
Figure 4-2. Crystal Cut Straps
The crystal has a cut strap (J111), which can be used to measure the oscillator safety factor
and is done by cutting the strap and adding a 0402 SMD resistor across the strap. The AN2648 application note from Microchip contains more
information about oscillator allowance and safety factors.
The online versions of the documents are provided as a courtesy. Verify all content and data in the device’s PDF documentation found on the device product page.
