4.2.7 Crystals

The SAM4E Xplained Pro kit contains two crystals that can be used as clock sources for the SAM4E device. Each crystal has a cut-strap next to it that can be used to measure the oscillator safety factor. This is done by cutting the strap and adding a resistor across the strap. More information about oscillator allowance and safety factor can be found in the Atmel application note AVR4100: Selecting and testing 32kHz crystal oscillators for Atmel AVR microcontrollers.

Table 4-12. External 32.768kHz Crystal
Pin on SAM4EFunction
PA7XIN32
PA8XOUT32
Table 4-13. External 12MHz Crystal
Pin on SAM4EFunction
PB9XIN
PB8XOUT
Important: Load capacitor calculation, selection and verification was done wrong in the design of the SAM4E Xplained Pro evaluation kit, see the errata section for more information.