I have stm32H74Zi chip and is running in 64Mhz clock speed and have scaled down the speed to 32Mhz for APB1 (I2C peripheral) using clock divider. Want to know how TIMINGR value is working with both the frequencies (32 and 64Mhz at APB1 peripheral).

[Umahe.1]

Using clock divider(/2) scaled down the APB1 peripheral clock speed to 32Mhz. Now I have different TIMINGR values for for each of 32 and 64MHz clock speed at APB1.

I tried 32MHz TIMINGR value for 64MHz clock speed and it worked.

I want to know how the TIMINGR value of APB1 peripheral with 32MHz speed is working with APB1 peripheral with clock speed of 64MHz?

[TDK]

I2C peripherals accept a wide range of clock rates. Presumably you are still within the allowable range and the pullups are adequate. Some clock stretching may also be happening.

[Umahe.1]

But I tried different TIMINGR values (standard, fast, ultra fast mode) at 64 MHz clock speed and it didn't work except with Fast Mode with the Thermal sensor (recommended fast mode).

Why is this?