STM32F765 EXTERNAL CRYSTAL

[Kishan Joshi]

I have custom stm32f765 board it has very minimal design. only some caps and resistor for the reset and boot. My problem is i have attached hse crystal of 16Mhz.

this one

https://www.digikey.in/product-detail/en/epson/TSX-3225-16-0000MF09Z-AC0/SER4069DKR-ND/5413941

and also 12pf ceramic capacitors. i have configured a code to work with hse but still it is not working is there anything i can do to check wether external crystal is working or not ?

by debugging the code i came to know that

while (__HAL_RCC_GET_FLAG(RCC_FLAG_HSERDY) == RESET)

    {

     if ((HAL_GetTick() - tickstart) > HSE_TIMEOUT_VALUE)

     {

      return HAL_TIMEOUT;

     }

    }

code is not going further from this lines  

Can you please guide my how can i debug. ? since the same code is working on the nucleo and nucleo has stlink external clock.

Thank you.

[Tesla DeLorean]

Not a software issue.

You'll want to tune the characteristics of the circuit, perhaps review application note, and check your math.

The STM32 permits the HSE to be output by MCO/PA8, this can be used to inspect the clock non-invasively.

More invasively you can probe the crystal pins, but this changes the capacitance. If probing causes it to start properly then it is a matter of getting the loading right.

[Tesla DeLorean]

Try some capacitors in the 4-5pF range

[Kishan Joshi]

Oh so 12pf won't work? I thought datasheet says 9pf. So 12pf will work fine. ​

[Piranha]

AN4661, AN4879, AN2867,

https://blog.adafruit.com/2012/01/24/choosing-the-right-crystal-and-caps-for-your-design/

NRST has an internal pull-up - remove the R2. That can also be related to your HSE problem.

[Kishan Joshi]

Oh ok , i thought we have to pull up the nrst.. i will try that out today and will report thank you sir..​ and that adafruit link is very helpful i will try these solutions and get back to you thank you