Atmel SAM4S Series, Preliminary Data Sheet

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509
11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
27.2.16.11 PMC Master Clock Register
Name: PMC_MCKR
Address: 0x400E0430
Access: Read-write
This register can only be written if the WPEN bit is cleared in “PMC Write Protect Mode Register” .
• CSS: Master Clock Source Selection
• PRES: Processor Clock Prescaler
• PLLADIV2: PLLA Divisor by 2
31 30 29 28 27 26 25 24
– – – – – – – –
23 22 21 20 19 18 17 16
– – – – – – – –
15 14 13 12 11 10 9 8
– – PLLBDIV2 PLLADIV2 – – – –
7 6 5 4 3 2 1 0
– PRES – – CSS
Value Name Description
0 SLOW_CLK Slow Clock is selected
1 MAIN_CLK Main Clock is selected
2 PLLA_CLK PLLA Clock is selected
3 PLLB_CLK PLLB Clock is selected
Value Name Description
0 CLK_1 Selected clock
1 CLK_2 Selected clock divided by 2
2 CLK_4 Selected clock divided by 4
3 CLK_8 Selected clock divided by 8
4 CLK_16 Selected clock divided by 16
5 CLK_32 Selected clock divided by 32
6 CLK_64 Selected clock divided by 64
7 CLK_3 Selected clock divided by 3
PLLADIV2 PLLA Clock Division
0 PLLA clock frequency is divided by 1.
1 PLLA clock frequency is divided by 2.