Is it possible two use a single crystal oscillator to clock two differnt stm MCUs on the same board?

[ma.alam9]

Hello All,

I was wondering if it is possible to clock another STM32 MCU (STMF031) using the single existing crystal oscillator that is currently clocking the main MCU (STM32F334). It could really save me space, power, cost and another clocking source on the board.

If yes, how?

BR

Asrar

[LMI2]

You can feed clock from external oscillator.

[ma.alam9]

I am feeding the clock from external oscillator (crystal oscillator "CX3225SB32000D0FPLCC"). The question is if I can use the same crystal oscillator to feed the clock of another STM MCU on the same board. Aim is to save and oscillator placement.

[Tesla DeLorean]

The parts start from their own internal RC clock source.

You're not going to be able to fork an crystal directly, but could with a TCXO, for example. If you've got significant fan-out/load, use a buffer.

Usually the best route is output the HSE via the MCO/PA8 pin, as this provides some buffering. ST does this with the ST-LINK on the NUCLEO/DISCO boards to save a crystal.

[Tesla DeLorean]

For radio or ethernet applications, most STM32 will take a TCXO input of upto 50 MHz (see datasheet fHSE parameter)