st10f269z1 STMicroelectronics, st10f269z1 Datasheet - Page 108

• Manufacturer Part Number: st10f269z1
• Description: St10f269 16-bit Mcu With Mac Unit, 256k Byte Flash Memory And 12k Byte Ram
• Manufacturer: STMicroelectronics

16 - REAL TIME CLOCK
16.1.2 - RTCPH & RTCPL: RTC PRESCALER
Registers
The 20-bit programmable prescaler divider is
loaded with 2 registers.
The 4 most significant bit are stored into RTCPH
and the 16 Less significant bit are stored in
RTCPL (EC06h)
RTCPH (EC08h)
Figure 52 : PRESCALER Register
The value stored into RTCPH, RTCPL is called RTCP (coded on 20-bit). The dividing ratio of the
Prescaler divider is: ratio = 64 x (RTCP)
16.1.3 - RTCDH & RTCDL: RTC DIVIDER Counters
Every basic reference clock the DIVIDER counters are reloaded with the value stored RTCPH and
RTCPL registers. To get an accurate time measurement it is possible to read the value of the DIVIDER,
reading the RTCDH, RTCDL. Those counters are read only. After any bit changed in the programmable
PRESCALER register, the new value is loaded in the DIVIDER.
RTCDL (EC0Ah)
RTCDH (EC0Ch)
Note: Those registers are not reset, and are read only.
108/184
15
15
15
15
3
19 18 17 16
14
14
14
14
2
RTCPH
1
13
13
13
13
0
12
12
12
12
15 14 13 12
11
11
11
11
15 14 13 12
RESERVED
RESERVED
10
10
10
10
9
9
9
9
11 10 9
20 bit word counter
11 10 9
8
8
8
8
RTCPL
RTCDL
XBUS
XBUS
XBUS
XBUS
RW
R
RTCPL. In order to keep the system clock, those
registers are not reset.
They are write protected by bit RTOFF of
RTCCON register, write operation is allowed if
RTOFF is set.
7
7
7
7
8
8
RTCPL
7
6
6
6
6
7
6
6
5
5
5
5
5
5
4
4
4
4
4
4
3
3
3
3
3
3
2
Reset Value: XXXXh
Reset Value: XXXXh
2
Reset Value: ---Xh
Reset Value: ---Xh
1
2
2
2
2
RTCPH
RTCDH
1
RW
0
R
ST10F269
0
1
1
1
1
0
0
0
0