STM32F4-Discovery RTC Hack
STM32F4-Discovery RTC Hack
STM32F4xx have a build in RTC (Real Time Clock) module. It is easy to use and can be driven by an internal or external 32,768 kHz reference clock. External 32.768 kHz clock reference is (by default) not fitted on the STM32F4-Discovery boards, but footprint of the crystal oscillator and load capacitors is provided on the PCB. The only issue is an additional VBAT voltage that is used as a backup supply for the RTC (as well as for additional backup registers and a small amout of backup SRAM memory).
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