Atmel Xplained Pro Evaluation Kit ATSAM4E-XPRO ATSAM4E-XPRO Data Sheet

575

SAM4E [DATASHEET]

Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14

 shows the main clock block diagram.

The main clock has two sources:



4/8/12 MHz fast RC oscillator which starts very quickly and is used at startup.



3 to 20 MHz crystal or ceramic resonator-based oscillator which can be bypassed.

XIN

XOUT

MOSCXTEN

MOSCXTST

MOSCXTS

Main Clock

Frequency

Counter

MAINF

SLCK

Slow Clock

3-20 MHz

Crystal

or

Ceramic Resonator

Oscillator

3-20 MHz

Oscillator

Counter

MOSCRCEN

Fast RC

Oscillator

MOSCRCS

MOSCRCF

MOSCRCEN

MOSCXTEN

MOSCSEL

MOSCSEL

MOSCSELS

1

0

MAINCK
Main Clock

MAINCK

Main Clock

Ref.

RCMEAS

CKGR_MCFR

CKGR_MOR

CKGR_MOR

CKGR_MOR

PMC_SR

PMC_SR

CKGR_MOR

CKGR_MOR

CKGR_MOR

CKGR_MOR

CKGR_MOR

CKGR_MCFR

PMC_SR

CKGR_MCFR

MAINFRDY