32KHz External Crystal Oscillator (XOSC32K) Control
Name:
XOSC32K
Offset:
0x14
Reset:
0x00000080
Access:
PAC Write-Protection
Bit15141312111098
WRTLOCKSTARTUP[2:0]
AccessR/WR/WR/WR/W
Reset0000
Bit76543210
ONDEMANDRUNSTDBYEN1KEN32KXTALENENABLE
AccessR/WR/WR/WR/WR/WR/W
Reset100000

Bit 12 – WRTLOCK: Write Lock

Write Lock

This bit locks the XOSC32K register for future writes, effectively freezing the XOSC32K configuration.

ValueDescription
0 The XOSC32K configuration is not locked.
1 The XOSC32K configuration is locked.

Bits 10:8 – STARTUP[2:0]: Oscillator Start-Up Time

Oscillator Start-Up Time

These bits select the start-up time for the oscillator.

The OSCULP32K oscillator is used to clock the start-up counter.

Table 1. Start-Up Time for 32KHz External Crystal Oscillator
STARTUP[2:0] Number of OSCULP32K Clock Cycles Number of XOSC32K Clock Cycles Approximate Equivalent Time
 [s]
0x0 2048 3 0.06
0x1 4096 3 0.13
0x2 16384 3 0.5
0x3 32768 3 1
0x4 65536 3 2
0x5 131072 3 4
0x6 262144 3 8
0x7 - - Reserved
Note:
  1. Actual Start-Up time is 1 OSCULP32K cycle + 3 XOSC32K cycles.
  2. The given time assumes an XTAL frequency of 32.768kHz.

Bit 7 – ONDEMAND: On Demand Control

On Demand Control

This bit controls how the XOSC32K behaves when a peripheral clock request is detected. For details, refer to XOSC32K Sleep Behavior.

Bit 6 – RUNSTDBY: Run in Standby

Run in Standby

This bit controls how the XOSC32K behaves during standby sleep mode. For details, refer to XOSC32K Sleep Behavior.

Bit 4 – EN1K: 1KHz Output Enable

1KHz Output Enable

ValueDescription
0 The 1KHz output is disabled.
1 The 1KHz output is enabled.

Bit 3 – EN32K: 32KHz Output Enable

32KHz Output Enable

ValueDescription
0 The 32KHz output is disabled.
1 The 32KHz output is enabled.

Bit 2 – XTALEN: Crystal Oscillator Enable

Crystal Oscillator Enable

This bit controls the connections between the I/O pads and the external clock or crystal oscillator.
ValueDescription
0 External clock connected on XIN32. XOUT32 can be used as general-purpose I/O.
1 Crystal connected to XIN32/XOUT32.

Bit 1 – ENABLE: Oscillator Enable

Oscillator Enable

ValueDescription
0 The oscillator is disabled.
1 The oscillator is enabled.