2025-06-18 2:07 AM
I am using an 8 MHz external oscillator and was planning to use a PLL to increase the system frequency. However, when I open the Clock Configuration tab in CubeMX, I don’t see any option for a PLL.
I’ve also shared a screenshot of the clock configuration where it’s clear that the PLL option is not available.
So my question is: Does the STM32C071CBT6 microcontroller support PLL with an external oscillator?
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2025-06-18 2:13 AM - edited 2025-06-18 2:14 AM
What makes you think the STM32C071CBT6 has a PLL?
There is no mention in the Datasheet
That would explain why CubeMX doesn't show it
2025-06-18 2:13 AM - edited 2025-06-18 2:14 AM
What makes you think the STM32C071CBT6 has a PLL?
There is no mention in the Datasheet
That would explain why CubeMX doesn't show it
2025-06-18 3:04 AM
@Andrew Neil wrote:There is no mention in the Datasheet
however, there are three mentions in the Reference Manual:
via: https://www.st.com/en/microcontrollers-microprocessors/stm32c071cb.html#documentation
@STTwo-32 These look like copy-paste errors in the RM ?
2025-06-19 2:22 AM
Hello @Andrew Neil
I've escalated this to the doc team for review (under internal ticket number 212567).
Best Regards.
STTwo-32
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2025-06-19 3:04 AM
Hi @STTwo-32
Is it possible to quickly confirm whether the PLL can be used with an external oscillator on the STM32C071CBT6?
Based on Cube MX and Andrew's suggestion, I am assuming that the STM32C071CBT6 does not support PLL functionality.
2025-06-19 3:06 AM - edited 2025-06-19 3:07 AM
The STM32C071CBT6 does not have a PLL - so it cannot "support" a thing it doesn't have!
What made you think it does have a PLL ?
2025-06-19 3:12 AM
Hi Andrew,
Thank you for your quick response. I was reviewing the user manual and came across a statement that says, "Optionally turn ON external Oscillator and/or device PLL." This wording left me a bit confused, so I just wanted to confirm whether the PLL can actually be used in this case.
2025-06-19 3:17 AM
@Andrew NeilBy the way, if the CUBE MX software does not provide a configuration option for the PLL, then I will stop exploring this further for now.
2025-06-19 3:26 AM - edited 2025-06-19 3:27 AM
As noted earlier, those look like copy-&-paste errors - and @STTwo-32 is looking into it.
If the PLL existed, it would be documented in the RM, and would appear in the Clock Tree: