18.8.3 Generator Control

GENCTRLn controls the settings of Generic Generator n (n=0..4).

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

Bit 3130292827262524 
 DIV[15:8] 
Access R/WR/WR/WR/WR/WR/WR/WR/W 
Reset 00000000 
Bit 2322212019181716 
 DIV[7:0] 
Access R/WR/WR/WR/WR/WR/WR/WR/W 
Reset 00000000 
Bit 15141312111098 
   RUNSTDBYDIVSELOEOOVIDCGENEN 
Access R/WR/WR/WR/WR/WR/W 
Reset 00000x 
Bit 76543210 
    SRC[4:0] 
Access R/WR/WR/WR/WR/W 
Reset xxxxx 

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.

ValueDescription
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.

ValueDescription
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.

ValueDescription
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.

ValueDescription
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.

ValueDescription
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.

ValueDescription
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