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Difficulty getting 16MHz HSE started

OtterCraft
Associate

Hi all,

I am testing a new dev board I designed to use a 16MHz crystal for the HSE. Been scouring the forums for a few days trying to find potential flaws in my design and/or solutions to no avail.

The MCU in question I am working with is the STM32F407ZET6.

The oscillator is TSX-3225 16.0000MF18X-AC0.

Following the STM32 oscillator design guide, I found the CL1,2 = 8pF, given the oscillator also has a capacitance of 9pF if we take into assumption (per ST guidelines) that stray capacitance of PCB/traces is 5pF. 

Oscillator is located directly next to MCU so I wouldn't think layout is problematic. 

I realize the feedback resistance may be a bit high, it's possible I made an error in my calculations from the worksheet--but it's worth noting that probing with an oscilloscope to see if the clock is working, I replaced the resistors with 0Ohm links as a last-ditch effort to no avail.

Looking for some design feedback and/or potential help getting crystal to work. Thanks!

OtterCraft_1-1702311885878.png

 

OtterCraft_0-1702311838280.png

 

 

1 ACCEPTED SOLUTION

Accepted Solutions
AScha.3
Principal III

1. osz32 is for a low power 32kHz crystal. 🙂 🙂

2. leave out the R -> 0 ohm

3. use HSE pins PH0/1 🙂

If you feel a post has answered your question, please click "Accept as Solution".

View solution in original post

3 REPLIES 3
AScha.3
Principal III

1. osz32 is for a low power 32kHz crystal. 🙂 🙂

2. leave out the R -> 0 ohm

3. use HSE pins PH0/1 🙂

If you feel a post has answered your question, please click "Accept as Solution".
MM..1
Chief

Sorry , but you miss pins for osc. Your pins is for 32kHz, i mean 16M never will work here.

Oh.. well. That would do it. 😂

Thanks--I have no clue how this was missed in the design review lol.