Datasheet

268
SAM4S [DATASHEET]
11100E–ATARM–24-Jul-13
16.6.2 RTC Mode Register
Name: RTC_MR
Address: 0x400E1464
Access: Read-write
• HRMOD: 12-/24-hour Mode
0 = 24-hour mode is selected.
1 = 12-hour mode is selected.
• PERSIAN: PERSIAN Calendar
0 = Gregorian Calendar.
1 = Persian Calendar.
• NEGPPM: NEGative PPM Correction
0 = positive correction (the divider will be slightly lower than 32768).
1 = negative correction (the divider will be slightly higher than 32768).
Refer to CORRECTION and HIGHPPM field descriptions.
• CORRECTION: Slow Clock Correction
0 = No correction
1..127 = The slow clock will be corrected according to the formula given below in HIGHPPM description.
• HIGHPPM: HIGH PPM Correction
0 = lower range ppm correction with accurate correction.
1 = higher range ppm correction with accurate correction.
If the absolute value of the correction to be applied is lower than 30ppm, it is recommended to clear HIGHPPM. HIGHPPM set to
1 is recommended for 30 ppm correction and above.
Formula:
If HIGHPPM = 0, then the clock frequency correction range is from 1.5 ppm up to 98 ppm. The RTC accuracy is less
than 1 ppm for a range correction from 1.5 ppm up to 30 ppm..
The correction field must be programmed according to the required correction in ppm, the formula is as follows:
31 30 29 28 27 26 25 24
– – TPERIOD – THIGH
23 22 21 20 19 18 17 16
– OUT1 – OUT0
15 14 13 12 11 10 9 8
HIGHPPM CORRECTION
76543210
– – – NEGPPM – – PERSIAN HRMOD
CORRECTION
3906
20 ppm×
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