Atmel SAM4L Xplained Pro Starter Kit Atmel ATSAM4L-XSTK ATSAM4L-XSTK Data Sheet
Product codes
ATSAM4L-XSTK
116
42023E–SAM–07/2013
ATSAM4L8/L4/L2
10.7.1
Main Clock Control
Name: MCCTRL
Access Type:
Read/Write
Offset: 0x000
Reset Value:
0x00000000
• MCSEL: Main Clock Select
Note:
1. If the 80MHz RC oscillator is selected as main clock source, it must be divided by at least 2 before being used as clock
source for the CPU. This division is selected by writing to the CPUSEL and CPUDIV bits in the CPUSEL register, before
switching to RC80M as main clock source.
switching to RC80M as main clock source.
Note that this register is protected by a lock. To write to this register the UNLOCK register has to be written first. Refer to
for details.
31
30
29
28
27
26
25
24
-
-
-
-
-
-
-
-
23
22
21
20
19
18
17
16
-
-
-
-
-
-
-
-
15
14
13
12
11
10
9
8
-
-
-
-
-
-
-
-
7
6
5
4
3
2
1
0
-
-
-
-
-
MCSEL
Table 10-4.
Main clocks in ATSAM4L.
MCSEL[2:0]
Main clock source
0
System RC oscillator (RCSYS)
1
Oscillator0 (OSC0)
2
PLL
3
DFLL
4
80MHz RC oscillator (RC80M)
5
4/8/12 MHz RC oscillator (RCFAST)
6
1 MHz RC oscillator (RC1M)
7
Reserved