34.8.1 Control A


Bit	31	30	29	28	27	26	25	24

Access
Reset


Bit	23	22	21	20	19	18	17	16
			COPEN1	COPEN0			CAPTEN1	CAPTEN0
Access			R/W	R/W			R/W	R/W
Reset			0	0			0	0


Bit	15	14	13	12	11	10	9	8
					ALOCK	PRESCALER[2:0]
Access					R/W	R/W	R/W	R/W
Reset					0	0	0	0


Bit	7	6	5	4	3	2	1	0
	ONDEMAND	RUNSTDBY	PRESCSYNC[1:0]		MODE[1:0]		ENABLE	SWRST
Access	R/W	R/W	R/W	R/W	R/W	R/W	R/W	W
Reset	0	0	0	0	0	0	0	0

Bits 20, 21 – COPENx Capture On Pin x Enable

Bit x of COPEN[13:0] selects the trigger source for capture operation, either events or I/O pin input.

Note: This bit field is enable-protected. This bit field is not write-synchronized.

Value	Description
0	Event from Event System is selected as trigger source for capture operation on channel x.
1	I/O pin is selected as trigger source for capture operation on channel x.

Bits 16, 17 – CAPTENx Capture Channel x Enable

Bit x of CAPTEN[31:0] selects whether channel x is a capture or a compare channel.

Note: This bit field is enable-protected. This bit field is not write-synchronized.

Value	Description
0	CAPTEN disables capture on channel x.
1	CAPTEN enables capture on channel x.

Bit 11 – ALOCK Auto Lock

When this bit is set, Lock bit update (LUPD) is set to '1' on each overflow/underflow or re-trigger event.

Note: This bit is enable-protected. This bit is not write-synchronized.

Value	Description
0	The LUPD bit is not affected on overflow/underflow, and re-trigger event.
1	The LUPD bit is set on each overflow/underflow or re-trigger event.

Bits 10:8 – PRESCALER[2:0] Prescaler

These bits select the counter prescaler factor.

Note: This bit field is enable-protected. This bit field is not write-synchronized.

Value	Name	Description
0x0	DIV1	Prescaler: GCLK_TC
0x1	DIV2	Prescaler: GCLK_TC/2
0x2	DIV4	Prescaler: GCLK_TC/4
0x3	DIV8	Prescaler: GCLK_TC/8
0x4	DIV16	Prescaler: GCLK_TC/16
0x5	DIV64	Prescaler: GCLK_TC/64
0x6	DIV256	Prescaler: GCLK_TC/256
0x7	DIV1024	Prescaler: GCLK_TC/1024

Bit 7 – ONDEMAND Clock On Demand

This bit selects the clock requirements when the TC is stopped.

In standby mode, if the Run in Standby bit (CTRLA.RUNSTDBY) is '0', ONDEMAND is forced to '0'.

Note: This bit is enable-protected. This bit is not write-synchronized.

Value	Description
0	The On Demand is disabled. If On Demand is disabled, the TC will continue to request the clock when its operation is stopped (STATUS.STOP=1).
1	The On Demand is enabled. When On Demand is enabled, the stopped TC will not request the clock. The clock is requested when a software re-trigger command is applied or when an event with start/re-trigger action is detected.

Bit 6 – RUNSTDBY Run in Standby

This bit is used to keep the TC running in standby mode.

Note: This bit is enable-protected. This bit is not write-synchronized.

Value	Description
0	The TC is halted in standby.
1	The TC continues to run in standby.

Bits 5:4 – PRESCSYNC[1:0] Prescaler and Counter Synchronization

These bits select whether the counter should wrap around on the next GCLK_TCx clock or the next prescaled GCLK_TCx clock. It also makes it possible to reset the prescaler.

Note: This bit field is enable-protected. This bit field is not write-synchronized.

Value	Name	Description
0x0	GCLK	Reload or reset the counter on next generic clock
0x1	PRESC	Reload or reset the counter on next prescaler clock
0x2	RESYNC	Reload or reset the counter on next generic clock. Reset the prescaler counter
0x3	-	Reserved

Bits 3:2 – MODE[1:0] Timer Counter Mode

These bits select the counter mode.

Note: This bit field is enable-protected. This bit field is not write-synchronized.

Value	Name	Description
0x0	COUNT16	Counter in 16-bit mode
0x1	COUNT8	Counter in 8-bit mode
0x2	COUNT32	Counter in 32-bit mode
0x3	-	Reserved

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 SYNCBUSY register (SYNCBUSY.ENABLE) will be set. SYNCBUSY.ENABLE will be cleared when the operation is complete.

Note:

This bit is not enable-protected.
This bit is write-synchronized: SYNCBUSY.ENABLE bit must be checked to ensure the CTRLA.ENABLE synchronization is complete.

Value	Description
0	The peripheral is disabled.
1	The peripheral is enabled.

Bit 0 – SWRST Software Reset

Writing a '0' to this bit has no effect.

Writing a '1' to this bit resets all registers in the TC, except DBGCTRL, to their initial state, and the TC will be disabled.

Writing a '1' to CTRLA.SWRST will always take precedence; all other writes in the same write-operation will be discarded.

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.

Note:

This bit is not enable-protected.
This bit is write-synchronized: SYNCBUSY.SWRST bit must be checked to ensure the CTRLA.SWRST synchronization is complete.

Value	Description
0	There is no reset operation ongoing.
1	The reset operation is ongoing.

Name:	CTRLA
Offset:	0x00
Reset:	0x00000000
Property:	PAC Write-Protection, Write-Synchronized bits, Enable-Protected bits