Crystals

The ATmega324PB Xplained Pro kit contains one mounted 16MHz crystal and a footprint for a 32.768kHz crystal that can be used as clock sources for the ATmega324PB. The crystals have cut-straps next to them that can be used to measure the oscillator safety factor. This is done by cutting the strap and adding a resistor across the strap. Information about oscillator allowance and safety factor can be found in application note AVR4100, information about clock calibration and compensation can be found in application note AT03155.

The footprint for the 32KHz crystal is based on the Micro Crystal Switzerland MS1V-T1K series.

Info: Note that PC6 and PC7 are shared signals. To disconnect PC6 and PC7 from all functionality except XTAL remove R211 and R212.

Table 1. External 32.768kHz Crystal Footprint
ATmega324PB pin	Function	Shared functionality
PC6	TOSC1	USER BUTTON/EXT3.9/EDBG GPIO3 via R211
PC7	TOSC2	USER LED/EXT3.4 via R212

Table 2. External 16MHz Crystal
ATmega324PB pin	Function	Shared functionality
PE0	XTAL2	-
PE1	XTAL1	-