Atmel ARM-Based Evaluation Kit AT91SAM9N12-EK AT91SAM9N12-EK Data Sheet
Product codes
AT91SAM9N12-EK
172
SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]
11063K–ATARM–05-Nov-13
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
3 to 20 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