HSE clock lagging above 16 Mhz

[ChaitanyaParate]

I am using 30 Mhz crystal oscillator, and when I configure clock for 30 Mhz it doesn't work properly but when I configure 16 Mhz it works properly.

[alfsch]

Using 30M as a crystal is /maybe  a problem : many crystals (over 20M or so) are made as overtone crystals, most 3. harmonic, so your 30M crystal might be a 10M crystal, thats used on 3. overtone.

If using such a crystal in standard oscillator circuit, it will run at 10M.

So better stay with lower (=standard) frequency crystals, 8 or 16 MHz , and you have a reliable clock.

If you need 30 or 40 M oscillator (why ? ) , then be sure to have not a model for use at overtone and have the load caps very small, to get it running at all.

[mƎALLEm]

Hello,

Is it the same behavior as the other thread ?

If yes start by reviewing the compatibility of the crystal by referring to the AN2867 and calculating the gain margin:

 

Do you get the gain margin > 5 based on what do you have in the HW?

what do you mean exactly by lagging? running at low frequency?

[Andrew Neil]

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@ChaitanyaParate wrote:

I am using 30 Mhz crystal oscillator, .

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Do you mean a crystal oscillator - or just a crystal ?

Difference between just a crystal, and a crystal oscillator.

 

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@ChaitanyaParate wrote:

 it doesn't work properly 

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What, exactly, does that mean:

• fails to oscillate at all ?
• does oscillates, but at wrong frequency? If so, what frequency?
• bursts into flames ?
• other ... ?

[ChaitanyaParate]

Its a crystal oscillator .

and by lag i mean when i put HAL_Delay(1000) I get a delay of almost 3 seconds when using 30, 32 , or 48 Mhz crystal oscillator.

[mƎALLEm]

Hello,

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@ChaitanyaParate wrote:

Its a crystal oscillator .

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Are you sure?

If yes, in that case you need to configure HSE in Bypass mode:

That configures one input GPIO for the crystal oscillator:

 

[mƎALLEm]

@ChaitanyaParate 

Please review this new article: How to select a compatible crystal and load capacitors for STM32 with layout guidelines