This register is write protected. The write access procedure is described in RTC register write protection on page9.
| CALM | Calibration minus The frequency of the calendar is reduced by masking CALM out of 220 RTCCLK pulses (32 seconds if the input frequency is 32768 Hz). This decreases the frequency of the calendar with a resolution of 0.9537 ppm. To increase the frequency of the calendar, this feature should be used in conjunction with CALP. See Section24.3.12: RTC smooth digital calibration on page13. |
| CALW16 | Use a 16-second calibration cycle period When CALW16 is set to 1, the 16-second calibration cycle period is selected.This bit must not be set to 1 if CALW8=1. Note: CALM[0] is stuck at 0 when CALW16= 1. Refer to Section24.3.12: RTC smooth digital calibration. |
| CALW8 | Use an 8-second calibration cycle period When CALW8 is set to 1, the 8-second calibration cycle period is selected. Note: CALM[1:0] are stuck at 00; when CALW8= 1. Refer to Section24.3.12: RTC smooth digital calibration. |
| CALP | Increase frequency of RTC by 488.5 ppm This feature is intended to be used in conjunction with CALM, which lowers the frequency of the calendar with a fine resolution. if the input frequency is 32768 Hz, the number of RTCCLK pulses added during a 32-second window is calculated as follows: (512 * CALP) - CALM. Refer to Section24.3.12: RTC smooth digital calibration. |