ALFAT SoC RTC

[LarryG]

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.

[Jeff_ghielectroncs]

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

[Dat_Tran]

@ LarryG -

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?

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.