45.7.1 Control A

Table 45-1. Register Bit Attribute Legend
Symbol	Description	Symbol	Description	Symbol	Description
R	Readable bit	HC	Cleared by Hardware	(Grey cell)	Unimplemented
W	Writable bit	HS	Set by Hardware	X	Bit is unknown at Reset
K	Write to clear	S	Software settable bit	—	—

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


Bit	31	30	29	28	27	26	25	24
	MAXCMP[3:0]					ANGULAR[2:0]
Access	RW	RW	RW	RW		RW	RW	RW
Reset	0	0	0	0		0	0	0


Bit	23	22	21	20	19	18	17	16
		PINVEN2	PINVEN1	PINVEN0		PINEN2	PINEN1	PINEN0
Access		RW	RW	RW		RW	RW	RW
Reset		0	0	0		0	0	0


Bit	15	14	13	12	11	10	9	8
	PEREN	SWAP			ALOCK	CONF[2:0]
Access	RW	RW			RW	RW	RW	RW
Reset	0	0			0	0	0	0


Bit	7	6	5	4	3	2	1	0
		RUNSTDBY			MODE[1:0]		ENABLE	SWRST
Access		RW			RW	RW	RW	W
Reset		0			0	0	0	0

Bits 31:28 – MAXCMP[3:0] Maximum Consecutive Missing Pulses

These bits define the threshold for the maximum consecutive missing pulses in AUTOC configuration of the QDEC mode.

Outside of AUTOC configuration of QDEC mode, these bits have no effect.

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

Bits 26:24 – ANGULAR[2:0] Angular Counter Length

In QDEC mode, these bits define the size of the Angular counter within COUNT. Angular counter size is equal to CTRLA.ANGULAR+9. The remaining MSB of the COUNTER register are used for counting revolutions.

For example, CTRLA.ANGULAR=0 defines the 9 LSB of COUNT as Angular counter and the residual 7 MSB of COUNT as Revolution counter. CTRLA.ANGULAR=7 will define a 16-bit Angular counter and no Revolution counter.

Outside of QDEC mode, these bits have no effect.

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

Table 45-2. Angular and Revolution Counters in COUNTER Register
ANGULAR[2:0]	Angular counter	Revolution counter
0x0	COUNTER[0:8]	COUNTER[9:15]
0x1	COUNTER[0:9]	COUNTER[10:15]
0x2	COUNTER[0:10]	COUNTER[11:15]
0x3	COUNTER[0:11]	COUNTER[12:15]
0x4	COUNTER[0:12]	COUNTER[13:15]
0x5	COUNTER[0:13]	COUNTER[14:15]
0x6	COUNTER[0:14]	COUNTER[15]
0x7	COUNTER[0:15]	no revolution counter

Bits 20, 21, 22 – PINVENx IO Pin x Invert Enable [x = 2..0]

When this bit is written to '1', the corresponding input pin active level is inverted. This bit has no effect if PINENx bit is zero.

In COUNTER mode only PINVEN[0] is significant.

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

Value	Description
0	Pin active level is not inverted.
1	Pin active level is inverted.

Bits 16, 17, 18 – PINENx PDEC Input From Pin x Enable [x = 2..0]

This bit enables the IO pin x as signal input.

In COUNTER mode, only PINEN[0] is significant.

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

Value	Description
0	Event line is the signal input.
1	I/O pin is the signal input.

Bit 15 – PEREN Period Enable

This bit is used to enable the CC0 register as counter period.

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

Value	Description
0	Period register function is disabled.
1	CC0 is acting as counter period register.

Bit 14 – SWAP PDEC Phase A and B Swap

This bit is used to swap input source of signal 0 and 1.

In COUNTER mode this bit has no effect.

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

Value	Description
0	The input sources of signal 0 and 1 are not swapped.
1	The input sources of signal 0 and 1 are swapped.

Bit 11 – ALOCK Auto Lock

When this bit is set, the Lock Update bit in Control B register (CTRLB.LUPD) is set by hardware when an UPDATE condition is detected.

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

Value	Description
0	Auto Lock is disabled.
1	Auto Lock is enabled.

Bits 10:8 – CONF[2:0] PDEC Configuration

These bits define the PDEC configuration.

Outside of QDEC mode, these bits have no effect.

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

Value	Name	Description
0	X4	Quadrature decoder direction
1	X4S	Secure Quadrature decoder direction
2	X2	Decoder direction
3	X2S	Secure decoder direction
4	AUTOC	Auto correction mode

Bit 6 – RUNSTDBY Run in Standby

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

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

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

Bits 3:2 – MODE[1:0] Operation Mode

These bits select one of the QDEC, HALL, COUNTER modes.

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

Value	Name	Description
0x0	QDEC	QDEC operating mode
0x1	HALL	HALL operating mode
0x2	COUNTER	COUNTER operating mode

Bit 1 – ENABLE Enable

Note:

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

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

Bit 0 – SWRST Software Reset

Write a ‘1’ to this bit to reset the SFR registers in PDEC (except DBGCTRL) to their initial state, and PDEC will be disabled. The bit stays high until reset completes. Setting this bit also sets the SYNCBUSY.SWRST to 1. SYNCBUSY.SWRST stays 1 until reset sequence completes.

Note:

When the CTRLA.SWRST is written, the user should poll the SYNCB.SWRST bit to know when the reset operation is complete.
During a SWRST, access to registers/bits without SWRST are disallowed until the SYNCBUSY.SWRST is cleared by the hardware.

Value	Description
0	There is no Reset operation ongoing.
1	A Reset operation is ongoing.