cant reach 64Mhz in STM32G071C8

[YWhit]

Hi

I'm developing on STM32G071C8 with the developing circuit

I'm trying to reach 64Mhz as system clock

I'm programing RCC->PLLCFGR as follows:

R=Q=2 (both on) . P=off N=16 M=2 or N=8 M=1 PLL source=HSI16

any combination above 54Mhz - disconnects Flash- so program memory reads all 0

what am I doing wrong

thanks

Yona

[andy2399]

STM32CubeMX seems to show that 64MHz cannot be achieved with the internal high speed oscillator.

However, using an external 8MHz oscillator allows for 64MHz as shown attached.

Andy

[Ozone]

I would not take CubeMX as reference, rather consult the datasheet/reference manual.

To be honest, I haven't any experience with the G07x MCUs.

[YWhit]

I havnt found any limitations to the PLL output (other than <=64Mhz) anywhere in the datasheet.

Yona

[mckenney · Accepted solution]

Did you bump your Flash Wait State setting in FLASH->ACR? RM0444 (rev2) Table 7 shows a breakpoint 1->2 around 48MHz.

[Edit: Fixed typo.]

[andy2399]

Except that the data sheet does not allow you to interactively try different sources and see the results.

Getting clocks configured correctly is not easy for inexperienced users and the UI is easier for them to comprehend that the manuals in my opinion.

Andy

[Ozone]

> Except that the data sheet does not allow you to interactively try different sources and see the results.

Unless you take a hasty, bug-prone CubeMX implementation into account, also based on the reference manual.

[YWhit]

it works!

thank you so much.

I didnt realize- that the flash needs that kind of attention.

Yona