PCF8523T register retention during battery switch over
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I am having a problem with the PCF8523T RTC chip, I occasionally lose time, and when this happens the control registers are back to there default states. Can some one tell me if the 3 control registers settings are retained during battery switch over, or are they returned to default and need to be written again?
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Hello David,
During battery switch-over, the device should keep the registers set and only the interface is disabled in battery backup operation. It looks like the RTC resets (a reset is automatically generated at power-on or initiated with the software reset command) and go back to the default values. After a reset, the RTC enters in the following mode:
- 768 kHz CLKOUT active
- 24 hour mode is selected
- Register Offset is set logic 0
- No alarms set
- Timers disabled
- No interrupts enabled
- Battery switch-over is disabled
- Battery low detection is disabled
- 7 pF of internal oscillator capacitor selected
Is this the case?
Also, can you please share your configuration in control bits PM[2:0] in register Control_3 (02h)? What is the voltage level of the battery VBAT and VDD?
Have a great day,
Paulina
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