Atmel Xplained Pro Evaluation Kit ATSAMD20-XPRO ATSAMD20-XPRO Ficha De Dados
Códigos do produto
ATSAMD20-XPRO
131
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129K–SAM-D20_datasheet–06/2014
16.6
Functional Description
16.6.1 Principle of Operation
XOSC, XOSC32K, OSC32K, OSCULP32K, OSC8M, DFLL48M, BOD33, and VREF are configured via SYSCTRL control
registers. Through this interface, the sub-peripherals are enabled, disabled or have their calibration values updated.
registers. Through this interface, the sub-peripherals are enabled, disabled or have their calibration values updated.
The Power and Clocks Status register gathers different status signals coming from the sub-peripherals controlled by the
SYSCTRL. The status signals can be used to generate system interrupts, and in some cases wake up the system from
standby mode, provided the corresponding interrupt is enabled.
SYSCTRL. The status signals can be used to generate system interrupts, and in some cases wake up the system from
standby mode, provided the corresponding interrupt is enabled.
The oscillator must be enabled to run. The oscillator is enabled by writing a one to the ENABLE bit in the respective
oscillator control register, and disabled by writing a zero to the oscillator control register. In idle mode, the default
operation of the oscillator is to run only when requested by a peripheral. In standby mode, the default operation of the
oscillator is to stop. This behavior can be changed by the user, see below for details.
oscillator control register, and disabled by writing a zero to the oscillator control register. In idle mode, the default
operation of the oscillator is to run only when requested by a peripheral. In standby mode, the default operation of the
oscillator is to stop. This behavior can be changed by the user, see below for details.
The behavior of the oscillators in the different sleep modes is shown in
To force an oscillator to always run in idle mode, and not only when requested by a peripheral, the oscillator
ONDEMAND bit must be written to zero. The default value of this bit is one, and thus the default operation in idle mode is
to run only when requested by a peripheral.
ONDEMAND bit must be written to zero. The default value of this bit is one, and thus the default operation in idle mode is
to run only when requested by a peripheral.
To force the oscillator to run in standby mode, the RUNSTDBY bit must be written to one. The oscillator will then run in
standby mode when requested by a peripheral (ONDEMAND is one). To force an oscillator to always run in standby
mode, and not only when requested by a peripheral, the ONDEMAND bit must be written to zero and RUNSTDBY must
be written to one.
standby mode when requested by a peripheral (ONDEMAND is one). To force an oscillator to always run in standby
mode, and not only when requested by a peripheral, the ONDEMAND bit must be written to zero and RUNSTDBY must
be written to one.
shows the behavior in the different sleep modes, depending on the settings of ONDEMAND and
RUNSTDBY.
Note that this does not apply to the OSCULP32K oscillator, which is always running and cannot be disabled.
Table 16-1. Behavior of the Oscillators
Oscillator
Idle 0,
1,
2
Standby
XOSC
Run on request
Stop
XOSC32K
Run on request
Stop
OSC32K
Run on request
Stop
OSCULP32K
Run
Run
OSC8M
Run on request
Stop
DFLL48M
Run on request
Stop
Table 16-2. Behavior in the different sleep modes
Sleep mode
ONDEMAND
RUNSTDBY
Behavior
Idle
0,
1, 2
0
X
Run
Idle
0,
1, 2
1
X
Run when requested by a peripheral
Standby
0
0
Stop
Standby
0
1
Run
Standby
1
0
Stop
Standby
1
1
Run when requested by a peripheral