How do I read an STM32H7 register?

Hello --

I am trying to read a register from the STM32H7 chip (GIGA R1). My first attempt was a simple fail --

void setup() {
Serial.begin(9600);
Serial.println(RCC_BDCR, BIN);
}
void loop() {}

Error received ...

Serial.println(RCC_BDCR, BIN);
                ^~~~~~~~
                RCC_C1

exit status 1

Compilation error: 'RCC_BDCR' was not declared in this scope

Thinking the "_C1" referred to the M7 core, I tried couple variations...

Serial.println(RCC_BDCR_C1, BIN);
...
Serial.println(RCC_C1_BDCR, BIN);

...to no avail.

I am really curious of the contents of this register, e.g. bits 9:8. Seems this might be the first of many steps toward getting the RTC running properly? I dunno really.

From what I gather, A(rduino)-Team designed a board whose chip has an on-board RTC, complemented that RTC with an external 32.768kHz crystal, but chose not to support that configuration in software. Rather, the on-board RTC is defaulted to an internal ~32kHz oscillator that is wildly inaccurate.

Any insight that might guide me on this is of course greatly appreciated.
Mark

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