Datasheet

ST10F269 16 - REAL TIME CLOCK
109/184
When RTCD increments to reach 00000h, The 20-bit word stored into RTCPH, RTCPL registers is loaded
in RTCD.
Bit 15 to bit 4 of RTCPH and RTCDH are not
used. When reading, the return value of those bit
will be zeros.
16.1.4 - RTCH & RTCL: RTC Programmable
COUNTER Registers
The RTC has 2 x 16-bit programmable counters
which count rate is based on the basic time
reference (for example 1 second). As the clock
oscillator may be kept working, even in power
down mode, the RTC counters may be used as a
system clock. In addition RTC counters and
registers are not modified at any system reset.
The only way to force their value is to write them
via the XBUS.
Those counters are write protected as well. The
bit RTOFF of the RTCCON register must be set
(RTC dividers and counters are stopped) to
enable a write operation on RTCH or RTCL.
A write operation on RTCH or RTCL register loads
directly the corresponding counter. When reading,
the current value in the counter (system date) is
returned.
The counters keeps on running while the clock
oscillator is working.
RTCL (EC0Eh) XBUS Reset Value: XXXXh
RTCH (EC10h) XBUS Reset Value: XXXXh
Note: Those registers are nor reset
Figure 53 : DIVIDER Counters
3 2 1 07 6 5 411 10 9 815 14 13 123 2 1 0
RTCDH
RTCDL
3 2 1 07 6 5 411 10 9 815 14 13 1219 18 17 16
20 bit word internal value of the Prescaler divider
1514131211109876543210
RTCL
RW
1514131211109876543210
RTCH
RW