STM32G4 does not output clock signals on MCO pin \ Where is the alternate function mapping table?

[KHarb.1]

I'm using CubeIDE and I have PG10 configured as MCO output and I see nothing. Usually when I see this, there is a HAL enable command I missed, but I don't think there is in this case.  

I've tried multiple clock sources and the pin stays at voltage high. I've checked on all the registers I know:

GPIOG

   MODER -> MODER10 = 0x2 (alternate function)

   AFRL = 0x0

   AFRH = 0x0

I suspect that having no alternate function set in AFR\L registers is what is not correctly set, but I don't see the mapping table mentioned in the reference manual:  "Refer to the “Alternate function mapping” table in the device datasheet for the detailed mapping of the alternate function I/O pins."

What should these registers be set to for MCO and where is the mapping table?

[TDK]

> Refer to the “Alternate function mapping” table in the device datasheet for the detailed mapping of the alternate function I/O pins.

So did you? The datasheet is a separate document from the reference manual.

MCO is AF0, so 0 is correct in those registers.

Make sure output speed is very high.

[KHarb.1]

Ahh...once again, datasheet and reference manual are different.  So, yes...AF0 is correct. 

The RCC register configuration all seemed correct.

If I'm not seeing MCO output, what else could I look at?

[TDK]

Configure it in CubeMX and see if it works. If it does, compare your register values against what it does instead. If it doesn't work, set pin up as a GPIO output and toggle it and verify on a scope that you're actually monitoring the pin and not something else.

[KHarb.1 · Accepted solution]

PG10 is also the NRST pin. I was able to trace this behavior to the NRST_MODE bits in FLASH_OPTR. I changed them from 0x3 to 0x2 and the MCO output started working along with normal GPIO which I also found to be failing.

[MasterT]

Check out 

WEAK void SystemClock_Config(void){}

there is a line for MCO, something like 

HAL_RCC_MCOConfig(RCC_MCO2, RCC_MCO2SOURCE_SYSCLK, RCC_MCODIV_4);

[TDK]

You should post your chip name in the title or opening post next time. Could have been solved much quicker.