SAM4L Datasheet, PDF (110/1185 Pages) ATMEL Corporation – ATSAM ARM-based Flash MCU

10.7.1 Main Clock Control
Name:
MCCTRL
Access Type:
Read/Write
Offset:
0x000
Reset Value:
0x00000000
ATSAM4L4/L2
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
• MCSEL: Main Clock Select
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)⁽¹⁾
5
4/8/12 MHz RC oscillator (RCFAST)
6
1 MHz RC oscillator (RC1M)
7
Reserved
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.
Note that this register is protected by a lock. To write to this register the UNLOCK register has to be written first. Refer to
Section 10.7.7 ”PM Unlock Register” on page 117 for details.
42023C–SAM–02/2013
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