32.768 kHz Crystal Oscillator Control A

Name:
XOSC32KCTRLA
Offset:
0x1C
Reset:
0x00
Access:
Configuration Change Protection
Bit76543210
RUNSTDBYCSUT[1:0]SELLPMODEENABLE
AccessR/WR/WR/WR/WR/WR/W
Reset000000

Bit 7 – RUNSTDBY: Run Standby

Run Standby

This bit controls whether the 32.768 kHz Crystal Oscillator (XOSC32K) is always running and in which modes when the ENABLE bit is ‘1’.
Notes:
  1. 1.The requesting peripheral, or the main clock, must take the oscillator start-up time into account.
  2. 2.The oscillator signal is only available if requested and will be available after a maximum of three XOSC32K cycles if the initial crystal start-up time has already ended.
ValueDescription
0 The XOSC32K oscillator will only run when requested by a peripheral or by the main clock in Active mode and Idle sleep mode (1)
1 The XOSC32K oscillator will always run in Active mode, Idle sleep mode, Standby sleep mode and Power-Down sleep mode (2)

Bits 5:4 – CSUT[1:0]: Crystal Start-Up Time

Crystal Start-Up Time

This bit field controls the 32.768 kHz Crystal Oscillator (XOSC32K) start-up time when the Source Select (SEL) bit is ‘0’.
Note: This bit field is read-only when the ENABLE bit or the XOSC32K Status (XOSCS) bit in the Main Clock Status (CLKCTRL.MCLKSTATUS) register is ‘1’.
ValueNameDescription
0x0 1K 1k cycles
0x1 16K 16k cycles
0x2 32K 32k cycles
0x3 64K 64k cycles

Bit 2 – SEL: Source Select

Source Select

This bit controls the source of the 32.768 kHz Crystal Oscillator (XOSC32K).

Note: This bit field is read-only when the ENABLE bit or the XOSC32K Status (XOSCS) bit in the Main Clock Status (CLKCTRL.MCLKSTATUS) register is ‘1’.
ValueDescription
0 External crystal connected to the XTAL32K1 and XTAL32K2 pins
1 External clock on the XTAL32K1 pin

Bit 1 – LPMODE: Low-Power Mode

Low-Power Mode

This bit controls whether the 32.768 kHz Crystal Oscillator (XOSC32K) is in Low-Power mode or not.
Note: Enabling the Low-Power mode can increase the crystal’s start-up time. Mitigate this by altering the crystal implementation to reduce serial resistance and overall capacitance or by disabling the Low-Power mode.
ValueDescription
0 The Low-Power mode is disabled
1 The Low-Power mode is enabled

Bit 0 – ENABLE: Enable

Enable

This bit controls whether the 32.768 kHz Crystal Oscillator (XOSC32K) is enabled or not.

ValueDescription
0 The XOSC32K oscillator is disabled
1 The XOSC32K oscillator is enabled and overrides normal port operation for the respective oscillator pins