20.7.9 DFLLULP Control

Name: DFLLULPCTRL
Offset: 0x1C
Reset: 0x0504
Property: PAC Write-Protection, Enable-Protected Bits, Write-synchronized Bits

Bit 15141312111098 
      DIV[2:0] 
Access R/WR/WR/W 
Reset 101 
Bit 76543210 
 ONDEMANDRUNSTDBYDITHERSAFEBINSEReservedENABLE  
Access R/WR/WR/WR/WR/WR/WR/W 
Reset 0000010 

Bits 10:8 – DIV[2:0] Division Factor

This field defines the division factor for the output frequency of the DFLLULP which depends on PL0 and PL2 modes.

This value which is determined and written during production, must be copied from the NVM software calibration row (DFLLULP Division Factor in PL0 or DFLLULP Division Factor in PL2) into the DFLLULPCTRL register by software.

The value must be changed before switching on a new Performance Level mode (PL0 or PL2).

Note: This bit field is enable-protected. This bit field is not synchronized.
ValueNameDescription
0x0 DIV1 Frequency divided by 1
0x1 DIV2 Frequency divided by 2
0x2 DIV4 Frequency divided by 4
0x3 DIV8 Frequency divided by 8
0x4 DIV16 Frequency divided by 16
0x5 DIV32 Frequency divided by 32
0x6 - 0x7 - Reserved

Bit 7 – ONDEMAND On Demand

The On Demand operation mode allows the oscillator to be enabled or disabled, depending on peripheral clock requests.

If the ONDEMAND bit has been previously written to '1', the oscillator will be running only when requested by a peripheral. If there is no peripheral requesting the oscillator’s clock source, the oscillator will be in a disabled state.

If On Demand is disabled, the oscillator will always be running when enabled.

In standby sleep mode, the On Demand operation is still active.

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

Bit 6 – RUNSTDBY Run in Standby

This bit controls how the DFLLULP behaves during standby sleep mode, together with the ONDEMAND bit.
Note: This bit is not enable-protected. This bit is not synchronized.

Bit 5 – DITHER Tuner Dither Mode

Note: This bit is enable-protected. This bit is not synchronized.
ValueDescription
0 The dither mode is disabled.
1 The dither mode is enabled.

Bit 4 – SAFE Tuner Safe Mode

Note: This bit is enable-protected. This bit is not synchronized.
ValueDescription
0 The clock output is not masked while binary search tuning is ongoing.
1 The clock output is masked while binary search tuning is ongoing (DFLLULPCTRL.BINSE = 1).

Bit 3 – BINSE Binary Search Enable

Note: This bit is enable-protected. This bit is not synchronized.
ValueDescription
0 Binary search tuning is disabled. Maximum number of reference clock cycles to acquire lock is 256.
1 Binary search tuning is enabled. Maximum number of reference clock cycles to acquire lock is 8.

Bit 2 – Reserved Must Be Set to 1

Bit 2 must always be set to ‘1’ when programming the DFLLULPCTRL register.

Bit 1 – ENABLE Enable

Note: This bit is write-synchronized: DFLLULPSYNCBUSY.ENABLE must be checked to ensure the DFLLULPCTRL.ENABLE synchronization is complete.
Note: This bit is not enable-protected.
ValueDescription
0 The DFLLULP is disabled.
1 The DFLLULP is enabled.