Is the xtal present on the board? Is the RTC clock enabled?
Yes, the cristal is present. The LSE init is done flawlessly, the problem is with the RTC init.
I have tried with LSI as RTC source, but problem remains.
I have verified that VBAT pin is connected to VDD on the board.
I have tried with another nucleo board since i had ordered two of them.
What is strange, is that i cannot write in the RTC registers, whatever i write, if i read them afterward, all the registers are zeroed.
Theses register are protected by a mechanism :
After system reset, the RTC registers are protected against parasitic write access by
clearing the DBP bit in the PWR_CR1 register (refer to the power control section). DBP bit
must be set in order to enable RTC registers write access.
After Backup domain reset, all the RTC registers are write-protected. Writing to the RTC
registers is enabled by writing a key into the Write Protection register, RTC_WPR.
The following steps are required to unlock the write protection on all the RTC registers
except for RTC_TAMPCR, RTC_BKPxR, RTC_OR and RTC_ISR[13:8].
1. Write ‘0xCA’ into the RTC_WPR register.
2. Write ‘0x53’ into the RTC_WPR register.
but the chibios hal take care of this, and this is the same code on F746 (where it works) than on F767.
I hope this is not a side effect of having a 'A' revision chip soldered on this devboard ?
Alexandre
