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ALFAT SoC RTC


#1

Two questions:

  1. After I init the RTC for backup mode, the first time I set the date/time via the S command, the ALFAT saves it. But any subsequent update via the S command doesn’t get saved (even though I get the !00 response). What gives?

  2. Your reference schematic (and your User Manual) say to use a crystal with a 12.5pf load capacitance along with 18pf caps. But per the STM32F205RBT6 manual, you should ‘never’ use a crystal with that value load capacitance (they recommend Cl <= 7pf with 8pf caps). Please explain.


#2

In reference to your 2nd question, our capacitors values are based on the particular crystal we use/test.


#3

@ LarryG -

I will check.
Righ now, make a cheat like this, switch to System mode, then setup date and time, then come back with backup mode.