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STM32F303CCT6 - SPI1 Prescaler Issue (Can't Set to 2)

Shreayas_Acharaya
Associate III

Hi everyone,

I'm working with the STM32F303CCT6 chip, and I've configured the system clock such that HCLK is running at 72 MHz.

I'm trying to configure SPI1 in full-duplex master mode using CubeMX / STM32CubeIDE. However, when I attempt to set the prescaler to 2, it gives me the following warning:

"With this Prescaler value and APB2 Clock Frequency (72.0 MHz), Baud Rate is more than 18.0 MBits/s.
Please set Prescaler more than 4."

This is confusing because I thought SPI1 could go up to 32 Mbit/s.

Has anyone encountered this?

  • Is this a limitation from CubeMX or HAL?

  • Is it safe to ignore this warning and proceed manually in code?

  • Or is there a hardware limitation I'm overlooking?

Any insights or workarounds would be greatly appreciated!

Thanks in advance!Screenshot 2025-07-11 174915.png

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