17.7.6 32 kHz External Crystal Oscillator (XOSC32K) Control
| Name: | XOSC32K |
| Offset: | 0x14 |
| Reset: | 0x2080 |
| Property: | PAC Write-Protection |
| Bit | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | |
| CGM[1:0] | WRTLOCK | STARTUP[2:0] | |||||||
| Access | R/W | R/W | R/W | R/W | R/W | R/W | |||
| Reset | 0 | 1 | 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 |
Bits 14:13 – CGM[1:0] Control Gain Mode
These bits control the gain of the external crystal oscillator.
| Value | Name | Description |
|---|---|---|
| 0x1 | XT | Standard mode |
| 0x2 | HS | High Speed mode |
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
These bits select the start-up time for the oscillator.
The OSCULP32K oscillator is used to clock the start-up counter.
| STARTUP[2:0] | Number of OSCULP32K Clock Cycles | Number of XOSC32K Clock Cycles | Approximate Equivalent Time [ms] |
|---|---|---|---|
| 0x0 | 2048 | 3 | 62.592 |
| 0x1 | 4096 | 3 | 125.092 |
| 0x2 | 16384 | 3 | 500.092 |
| 0x3 | 32768 | 3 | 1000.0092 |
| 0x4 | 65536 | 3 | 2000.0092 |
| 0x5 | 131072 | 3 | 4000.0092 |
| 0x6 | 262144 | 3 | 8000.0092 |
| 0x7 | - | - | Reserved |
Note:
- Actual Start-Up time is 1 OSCULP32K cycle + 3 XOSC32K cycles.
- The given time assumes an XTAL frequency of 32.768 kHz.
Bit 7 – ONDEMAND On Demand Control
This bit controls how the XOSC32K behaves when a peripheral clock request is detected. For details, refer to Table 17-1.
Bit 6 – RUNSTDBY Run in Standby
This bit controls how the XOSC32K behaves during standby sleep mode. For details, refer to Table 17-1.
Bit 4 – EN1K 1 kHz Output Enable
| Value | Description |
|---|---|
| 0 | The 1.024 kHz output is disabled. |
| 1 | The 1.024 kHz output is enabled. |
Bit 3 – EN32K 32 kHz Output Enable
| Value | Description |
|---|---|
| 0 | The 32.768 kHz output is disabled. |
| 1 | The 32.768 kHz 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. |