24.8.6 32 KHz External Crystal Oscillator (XOSC32K) Control
Name: | XOSC32K |
Offset: | 0x14 |
Reset: | 0x00000080 |
Property: | PAC Write-Protection |
Bit | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | |
WRTLOCK | STARTUP[2:0] | ||||||||
Access | R/W | R/W | R/W | R/W | |||||
Reset | 0 | 0 | 0 | 0 |
Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
ONDEMAND | RUNSTDBY | EN1K | EN32K | XTALEN | ENABLE | ||||
Access | R/W | R/W | R/W | R/W | R/W | R/W | |||
Reset | 1 | 0 | 0 | 0 | 0 | 0 |
Bit 12 – WRTLOCK Write Lock
This bit locks the XOSC32K register for future writes, effectively freezing the XOSC32K configuration.
Value | Description |
---|---|
0 | The XOSC32K configuration is not locked. |
1 | The XOSC32K configuration is locked. |
Bits 10:8 – STARTUP[2:0] Oscillator Start-Up Time
This bit field selects the XOSC32K crystal oscillator stabilization time.
Important: This stabilization time is for guidance only. A major component
of crystal start-up time is based on the second party crystal MFG parasitics that are
outside the scope of this specification. If this is a major concern, the customer
would need to characterize this based on their design choices.
STARTUP[2:0] | Number of OSCULP32K Clock Cycles | Approximate Equivalent Time (2)[s] |
---|---|---|
0x0 | 2048 | 0.06 |
0x1 | 4096 | 0.13 |
0x2 | 16384 | 0.5 |
0x3 | 32768 | 1 |
0x4 | 65536 | 2 |
0x5 | 131072 | 4 |
0x6 | 262144 | 8 |
0x7 | Reserved | Reserved |
Note:
- The OSCULP32K oscillator is used to clock the start-up counter.
- Actual Start-Up time is the number of selected OSCULP32K cycles + 3 XOSC32K cycles.
Bit 7 – ONDEMAND 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
This bit controls how the XOSC32K behaves during Standby sleep mode. For details, refer to XOSC32K Sleep Behavior.
Bit 4 – EN1K 1KHz Output Enable
Value | Description |
---|---|
0 | The 1KHz output is disabled. |
1 | The 1KHz output is enabled. |
Bit 3 – EN32K 32KHz Output Enable
Value | Description |
---|---|
0 | The 32KHz output is disabled. |
1 | The 32KHz output is enabled. |
Bit 2 – XTALEN Crystal Oscillator Enable
Value | Description |
---|---|
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
Value | Description |
---|---|
0 | The oscillator is disabled. |
1 | The oscillator is enabled. |