Value
Description
0
STATUS.BUFOVF is asserted when it occurs in the data stream.
1
STATUS.BUFOVF is asserted immediately upon buffer overflow.
Bit 7 – RUNSTDBY: Run In Standby
This bit defines the functionality in standby sleep mode.
This bit is not synchronized.
RUNSTDBY External Clock
Internal Clock
0x0
External clock is disconnected when
ongoing transfer is finished. All
reception is dropped.
Generic clock is disabled when ongoing transfer is
finished. The device can wake up on Transfer
Complete interrupt.
0x1
Wake on Receive Complete interrupt. Generic clock is enabled in all sleep modes. Any
interrupt can wake up the device.
Bits 4:2 – MODE[2:0]: Operating Mode
These bits select the USART serial communication interface of the SERCOM.
These bits are not synchronized.
Value
Description
0x0
USART with external clock
0x1
USART with internal clock
Bit 1 – ENABLE: Enable
Due to synchronization, there is delay from writing CTRLA.ENABLE until the peripheral is enabled/
disabled. The value written to CTRLA.ENABLE will read back immediately and the Enable
Synchronization Busy bit in the Synchronization Busy register (SYNCBUSY.ENABLE) will be set.
SYNCBUSY.ENABLE is cleared when the operation is complete.
This bit is not enable-protected.
Value
Description
0
The peripheral is disabled or being disabled.
1
The peripheral is enabled or being enabled.
Bit 0 – SWRST: Software Reset
Writing '0' to this bit has no effect.
Writing '1' to this bit resets all registers in the SERCOM, except DBGCTRL, to their initial state, and the
SERCOM will be disabled.
Writing '1' to CTRLA.SWRST will always take precedence, meaning that all other writes in the same write-
operation will be discarded. Any register write access during the ongoing reset will result in an APB error.
Reading any register will return the reset value of the register.
Due to synchronization, there is a delay from writing CTRLA.SWRST until the reset is complete.
CTRLA.SWRST and SYNCBUSY.SWRST will both be cleared when the reset is complete.
This bit is not enable-protected.
Atmel SAM L22G / L22J / L22N [DATASHEET]
Atmel-42402E-SAM L22G / L22J / L22N_Datasheet_Complete-07/2016
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