Cryistal choice

[mahmoud boroumand]

Posted on August 16, 2017 at 09:04

Hello

I use stm32f030p4 .I confused about select appropriate for HSE.

I want use maximum speed of MCU(48mhz) and i saw at datasheet i can use crystal between 4-32mhz .

How much crystal is the best for my work(Accurate)?

[Szymon PANECKI]

Posted on August 16, 2017 at 09:46

Hello Mahmoud,

Let me start with clarification of the part number, which you mentioned. I don't recognize STM32f030P4. Can you check if there is a typo and you mean STM32f030F4?

This is correct that STM32F0 can run up to 48MHz and the maximum value of HSE crystal frequency is 32 MHz. The explanation of this is that STM32 needs to use internal PLL (PLLCLK) to get 48 MHz. This frequency can be achieved with either HSE (4-32MHz) or HSI (8MHz).

If you decide to use HSE, I would recommend you to take a look on dedicated application note, which focuses on oscillator design for STM32. This is

http://www.st.com/resource/en/application_note/cd00221665.pdf

. You can find there information how to select STM32-compatible crystal. You can also find there some recommended resonators for STM32.

Regards

Szymon

[Tesla DeLorean]

Posted on August 16, 2017 at 16:57

>>How much crystal is the best for my work(Accurate)?

The one with the best PPM or PPB rating will be the most accurate. If you need accuracy over temperature consider a TCXO

What percent accuracy is required by USB? Are you using this in a radio application?

The STM32 has a PLL, which along with an internal VCO, can generate an assortment of frequencies. The limitations in a specific model of STM32 with respect to the PLL dividers and multiplier settings will constrain your choice of crystal speed.

[mahmoud boroumand]

Posted on August 17, 2017 at 13:00

hello

Turvey.Clive.002

Actually i have multi multi board and those are doesn't work together and have delay between them. want those are work together without any delay what can i do?