18.8.3 Generator Control


Bit	31	30	29	28	27	26	25	24
	DIV[15:8]
Access	R/W	R/W	R/W	R/W	R/W	R/W	R/W	R/W
Reset	0	0	0	0	0	0	0	0


Bit	23	22	21	20	19	18	17	16
	DIV[7:0]
Access	R/W	R/W	R/W	R/W	R/W	R/W	R/W	R/W
Reset	0	0	0	0	0	0	0	0


Bit	15	14	13	12	11	10	9	8
			RUNSTDBY	DIVSEL	OE	OOV	IDC	GENEN
Access			R/W	R/W	R/W	R/W	R/W	R/W
Reset			0	0	0	0	0	x


Bit	7	6	5	4	3	2	1	0
				SRC[4:0]
Access				R/W	R/W	R/W	R/W	R/W
Reset				x	x	x	x	x

Bits 31:16 – DIV[15:0] Division Factor

These bits represent a division value for the corresponding Generator. The actual division factor is dependent on the state of DIVSEL. The number of relevant DIV bits for each Generator can be seen in this table. Written bits outside of the specified range will be ignored.

Table 18-6. Division Factor Bits
Generic Clock Generator	Division Factor Bits
Generator 0	8 division factor bits - DIV[7:0]
Generator 1	16 division factor bits - DIV[15:0]
Generator 2 - 4	8 division factor bits - DIV[7:0]

Bit 13 – RUNSTDBY Run in Standby

This bit is used to keep the Generator running in Standby as long as it is configured to output to a dedicated GCLK_IO pin. If GENCTRLn.OE is zero, this bit has no effect and the generator will only be running if a peripheral requires the clock.

Value	Description
0	The Generator is stopped in Standby and the GCLK_IO pin state (one or zero) will be dependent on the setting in GENCTRL.OOV.
1	The Generator is kept running and output to its dedicated GCLK_IO pin during Standby mode.

Bit 12 – DIVSEL Divide Selection

This bit determines how the division factor of the clock source of the Generator will be calculated from DIV. If the clock source should not be divided, DIVSEL must be 0 and the GENCTRLn.DIV value must be either 0 or 1.

Value	Description
0	The Generator clock frequency equals the clock source frequency divided by GENCTRLn.DIV.
1	The Generator clock frequency equals the clock source frequency divided by 2^(N+1), where N is the Division Factor Bits for the selected generator (refer to GENCTRLn.DIV).

Bit 11 – OE Output Enable

This bit is used to output the Generator clock output to the corresponding pin (GCLK_IO), as long as GCLK_IO is not defined as the Generator source in the GENCTRLn.SRC bit field.

Value	Description
0	No Generator clock signal on pin GCLK_IO.
1	The Generator clock signal is output on the corresponding GCLK_IO, unless GCLK_IO is selected as a generator source in the GENCTRLn.SRC bit field.

Bit 10 – OOV Output Off Value

This bit is used to control the clock output value on pin (GCLK_IO) when the Generator is turned off or the OE bit is zero, as long as GCLK_IO is not defined as the Generator source in the GENCTRLn.SRC bit field.

Value	Description
0	The GCLK_IO will be LOW when generator is turned off or when the OE bit is zero.
1	The GCLK_IO will be HIGH when generator is turned off or when the OE bit is zero.

Bit 9 – IDC Improve Duty Cycle

This bit is used to improve the duty cycle of the Generator output to 50/50 for odd division factors.

Value	Description
0	Generator output clock duty cycle is not balanced to 50/50 for odd division factors.
1	Generator output clock duty cycle is 50/50.

Bit 8 – GENEN Generator Enable

This bit is used to enable and disable the Generator.

Value	Description
0	Generator is disabled.
1	Generator is enabled.

Bits 4:0 – SRC[4:0] Generator Clock Source Selection

These bits select the Generator clock source, as shown in this table.

Table 18-3. Generator Clock Source Selection
Value	Name	Description
0x00	XOSC	XOSC oscillator output
0x01	GCLK_IN	Generator input pad (GCLK_IO)
0x02	GCLK_GEN1	Generic clock generator 1 output
0x03	OSCULP32K	OSCULP32K oscillator output
0x04	XOSC32K	XOSC32K oscillator output
0x05	OSC16M	OSC16M oscillator output
0x06	DFLLULP	DFLLULP ultra low power output
0x07	FDPLL96M	FDPLL96M output
0x08-0x1F	Reserved	Reserved for future use

A Power Reset will reset all GENCTRLn registers. the Reset values of the GENCTRLn registers are shown in table below.

Table 18-4. GENCTRLn Reset Value after a Power Reset
GCLK Generator	Reset Value after a Power Reset
0	0x00000105
others	0x00000000

A User Reset will reset the associated GENCTRL register unless the Generator is the source of a locked Peripheral Channel (PCHCTRLm.WRTLOCK=1). The reset values of the GENCTRL register are as shown in the table below.

Table 18-5. GENCTRLn Reset Value after a User Reset
GCLK Generator	Reset Value after a User Reset
0	0x00000105
others	No change if the generator is used by a Peripheral Channel m with PCHCTRLm.WRTLOCK=1 else 0x00000000

Name:	GENCTRLn
Offset:	0x20 + n*0x04 [n=0..4]
Reset:	0x00000105 (GENCTRL0), 0x00000000 (others)
Property:	PAC Write-Protection, Write-Synchronized