Sony CXD5602 User Manual page 209

3.6.5.3.3 Synchronization of External RTC
Synchronization of External RTC is a function that sets time of RTC inside CXD5602 by receiving interrupts
from outside including PMIC (PMIC_INT).
Synchronizing CXD5602 with CXD5247
The sequence when CXD5602 (hereinafter called the LSI) is synchronized with CXD5247 (hereinafter called the
PMIC) is described below. As frequency and synchronizing timing depend on connected PMIC setting, adjust the
time to synchronize in accordance with PMIC.
1. PMU confirms RTC Counter value of PMIC.
2. Set the time when PMIC outputs External Alarm Flag (Interrupt from PMIC_INT).
For example, when the time that you want to synchronize is Y[46:0], set Y[46:6]-1 as the time that External
Alarm Flag is output.
(Y must be future time value compared with the RTC Counter value that was confirmed in 1 above.)
3. On WrReg(Post/Pre)Cnt register, write the time Y[46:0]+0x3+Δ that synchronizes with internal RTC.Δ is a
difference between the LSI and the PMIC. For details, refer to chapter "Difference Calculation between
CXD5602 and CXD5247".
When Δ is 0x0, calculate the formula replacing the Δ with 0x40. When the synchronization is performed
between internal RTCs, calculate the formula replacing the Δ with 0x40 at all times.
The following are examples of setting synchronizing internal RTC with external RTC.
Table RTC-69 Examples of Setting Synchronizing Internal RTC with External RTC Synchronization Setting
Desired Time
for
Synchronization
Y[46:0]
0x100
0x140
Difference Δ between
Output Time of
External Alarm Flag the LSI and PMIC
Y[46:6]-1 0x00 ~ 0x3F
0x3 0x00
0x01
0x02
...
0x3E
0x3F
0x4 0x00
0x01
0x02
...
0x3E
0x3F
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CXD5602 User Manual
RTC Synchronization Time Setting
for the LSI
(WrReg(Post/Pre)Cnt)
Y[46:0]+0x03+ Δ
0x143 ( = 0x100 + 0x03 + 0x40 )
0x104 ( = 0x100 + 0x03 + 0x01 )
0x105 ( = 0x100 + 0x03 + 0x02 )
...
0x141 ( = 0x100 + 0x03 + 0x3E )
0x142 ( = 0x100 + 0x03 + 0x3F )
0x183 ( = 0x140 + 0x03 + 0x40 )
0x144 ( = 0x140 + 0x03 + 0x01 )
0x145 ( = 0x140 + 0x03 + 0x02 )
...
0x181 ( = 0x140 + 0x03 + 0x3E )
0x182 ( = 0x140 + 0x03 + 0x3F )