506
11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
27.2.16.8
PMC Clock Generator Main Clock Frequency Register
Name:
CKGR_MCFR
Address:
0x400E0424
Access:
Read-Write
This register can only be written if the WPEN bit is cleared in
“PMC Write Protect Mode Register”
• MAINF: Main Clock Frequency
Gives the number of Main Clock cycles within 16 Slow Clock periods.
• MAINFRDY: Main Clock Ready
0 = MAINF value is not valid or the Main Oscillator is disabled or a measure has just been started by means of RCMEAS.
1 = The Main Oscillator has been enabled previously and MAINF value is available.
• RCMEAS: RC Oscillator Frequency Measure (write-only)
0 = No effect.
1 = Restart a measure of the main RC frequency, MAINF will carry the new frequency as soon as a low to high transition
occurs on MAINFRDY flag.
The measure is performed on the main frequency (i.e. not limited to RC oscillator only) but if the main clock frequency
source is the fast crystal oscillator, the restart of the measure is unneeded because of the well known stability of crystal
oscillators.
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
RCMEAS
–
–
–
MAINFRDY
15
14
13
12
11
10
9
8
MAINF
7
6
5
4
3
2
1
0
MAINF
Summary of Contents for SAM4S Series
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Page 1143: ...1143 11100B ATARM 31 Jul 12 SAM4S Series Preliminary Figure 43 4 64 lead LQFP Package Drawing ...
Page 1145: ...1145 11100B ATARM 31 Jul 12 SAM4S Series Preliminary Figure 43 5 64 lead QFN Package Drawing ...