Atmel ARM-Based Evaluation Kit for SAM4S16C, 32-Bit ARM® Cortex® Microcontroller ATSAM4S-WPIR-RD ATSAM4S-WPIR-RD Data Sheet

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SAM4S Series [DATASHEET]

Atmel-11100G-ATARM-SAM4S-Datasheet_27-May-14

The Power Management Controller (PMC) optimizes power consumption by controlling all system and user 

peripheral clocks. The PMC enables/disables the clock inputs to many of the peripherals and the Cortex-M4 

processor.
The Supply Controller selects between the 32 kHz RC oscillator or the slow crystal oscillator. The unused oscillator 

is disabled automatically so that power consumption is optimized.
By default, at start-up the chip runs out of the master clock using the fast RC oscillator running at 4 MHz.
The user can trim the 8 and 12 MHz RC oscillator frequencies by software.

The Power Management Controller provides the following clocks:



MCK, the Master Clock, programmable from a few hundred Hz to the maximum operating frequency of the 

device. It is available to the modules running permanently, such as the Enhanced Embedded Flash 

Controller.



Processor Clock (HCLK) , automatically switched off when entering the processor in Sleep Mode.



Free running processor Clock (FCLK) 



The Cortex-M4 SysTick external clock 



UDP Clock (UDPCK), required by USB Device Port operations.



Peripheral Clocks, typically MCK, provided to the embedded peripherals (USART, SPI, TWI, TC, etc.) and 

independently controllable. In order to reduce the number of clock names in a product, the Peripheral Clocks 

are named MCK in the product datasheet.



Programmable Clock Outputs can be selected from the clocks provided by the clock generator and driven on 

the PCKx pins.



Write Protected Registers

The Power Management Controller also provides the following operations on clocks:



A main crystal oscillator clock failure detector.



A frequency counter on main clock and an on-the-fly adjustable main RC oscillator frequency.