Atmel Evaluation Kit AT91SAM9X25-EK AT91SAM9X25-EK Data Sheet
Product codes
AT91SAM9X25-EK
172
SAM9X25 [DATASHEET]
11054E–ATARM–10-Mar-2014
21.5 Main Clock
Figure 21-3. Main Clock Block Diagram
The Main Clock has two sources:
12 MHz Fast RC Oscillator which starts very quickly and is used at startup
12 to 16 MHz Crystal Oscillator, which can be bypassed
XIN
XOUT
MOSCXTEN
MOSCXTCNT
MOSCXTS
Main Clock
Frequency
Counter
MAINF
MAINRDY
SLCK
Slow Clock
3-20 MHz
Crystal
Oscillator
3-20 MHz Crystal
Oscillator
Counter
MOSCRCEN
12 MHz
Fast RC
Oscillator
MOSCRCS
MOSCRCF
MOSCRCEN
MOSCXTEN
MOSCSEL
MOSCSEL
MOSCSELS
1
0
MAINCK
Main Clock