at91sam9g20-cu ATMEL Corporation, at91sam9g20-cu Datasheet - Page 291

• Manufacturer Part Number: at91sam9g20-cu
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

26.8
26.8.1
6384B–ATARM–15-Dec-08
Clock Switching Details
Master Clock Switching Timings
Table
from one selected clock to another one. This is in the event that the prescaler is de-activated.
When the prescaler is activated, an additional time of 64 clock cycles of the new selected clock
has to be added.
Table 26-1.
Notes:
Table 26-2.
To
Main Clock
SLCK
PLL Clock
To
PLLA Clock
PLLB Clock
26-1and
1. PLL designates either the PLL A or the PLL B Clock.
2. PLLCOUNT designates either PLLACOUNT or PLLBCOUNT.
From
From
Clock Switching Timings (Worst Case)
Clock Switching Timings (Worst Case)
Table 26-2
PLLCOUNT x SLCK +
0.5 x Main Clock +
0.5 x Main Clock +
2.5 x PLLx Clock
Main Clock
4 x SLCK +
4.5 x SLCK
give the worst case timings required for the Master Clock to switch
PLLACOUNT x SLCK
–
2.5 x PLLA Clock +
3 x PLLB Clock +
1.5 x PLLB Clock
PLLA Clock
4 x SLCK +
4 x SLCK +
AT91SAM9G20 Preliminary
PLLCOUNT x SLCK
2.5 x PLL Clock +
2.5 x Main Clock
4 x SLCK +
5 x SLCK +
SLCK
–
PLLBCOUNT x SLCK
2.5 x PLLB Clock +
3 x PLLA Clock +
1.5 x PLLA Clock
PLLB Clock
4 x SLCK +
4 x SLCK +
PLLCOUNT x SLCK
2.5 x PLL Clock +
3 x PLL Clock +
3 x PLL Clock +
1 x Main Clock
4 x SLCK +
4 x SLCK +
PLL Clock
5 x SLCK
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