5.2.2
Mechanical Switch
The PIC18F16Q40 Curiosity Nano board has one mechanical switch. This is a generic user-configurable switch.
When the switch is pressed, it will drive the I/O line to ground (GND).
Tip:
There is no externally connected pull-up resistor on the switch. To use the switch, make sure that an
internal pull-up resistor is enabled on pin RC0.
Table 5-2. Mechanical Switch
PIC18F16Q40 Pin
Description
Shared Functionality
RC0
User switch (SW0)
5.2.3
Crystal
The PIC18F16Q40 Curiosity Nano Board has a 32.768 kHz crystal footprint made for standard 3.2 mm by 1.5 mm
surface mount crystals with two terminals.
The crystal footprint is not connected to the PIC18F16Q40 by default, as the GPIOs are routed out to the edge
connector. To use the crystal, some hardware modifications are required.
• 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, marked RA4 and
RA5.
• Connect the crystal by soldering on a solder blob on each of the circular solder points next to the crystal on the
top side of the board, J210 and J211.
The crystal has a cut-strap next (J209) to it, which can be used to measure the oscillator safety factor. This is done by
cutting the strap and adding a 0402 SMD resistor across the strap. More information about oscillator allowance and
safety factor can be found in the
application note from Microchip.
The cut straps and solder points can be seen in
Table 5-3. Crystal Connections
PIC18F16Q40 Pin
Function
Shared Functionality
RA4
SOSCO (Crystal output)
RA5
SOSCI (Crystal input)
Figure 5-4. Crystal Connection and Cut Straps
Top side
Bo
�
om side
J208
J207
J211
J210
32.768 kHz
Crystal footprint
J209
PIC18F16Q40 Curiosity Nano
Hardware User Guide
©
2020 Microchip Technology Inc.
User Guide
DS50003047A-page 27
