14.8.18 XOSC_CTRL
The XOSC_CTRL register controls the operation of the crystal oscillator.
| Name: | XOSC_CTRL |
| Offset: | 0x12 |
| Reset: | 0xF0 |
| Property: | - |
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| XTAL_MODE[3:0] | XTAL_TRIM[3:0] | ||||||||
| Access | R/W | R/W | R/W | R/W | R/W | R/W | R/W | R/W | |
| Reset | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | |
Bits 7:4 – XTAL_MODE[3:0] XTAL_MODE
The register bits XTAL_MODE sets the operating mode of the crystal oscillator.
| Value | Description |
|---|---|
| 0x4 | Internal crystal oscillator disabled, use external reference frequency |
| 0xF | Internal crystal oscillator enabled and XOSC voltage regulator enabled |
| All other values are reserved |
For normal operation the default value is set to XTAL_MODE = 0xF after reset. Using an external clock source it is recommended to set XTAL_MODE = 0x4.
Bits 3:0 – XTAL_TRIM[3:0] XTAL_TRIM
The register bits XTAL_TRIM control internal capacitance arrays connected to the XTAL1 and XTAL2 pins.
| Value | Description |
|---|---|
| 0x0 |
A capacitance value in the range from 0pF to 4.5pF is selectable with a resolution of 0.3pF. Valid values are [0xF, 0xE, …, 0x0]. |