I2S clock on STM32F303 stuck at 8MHz in CubeMX?

[David Koster]

I'm trying to get I2S working on an STM32F303CBTx, but am having trouble configuring the pheripheral in STM32CubeMX.

In the reference manual I read:

9.2.12 I2S clock (only in STM32F303xB/C/D/E, STM32F358xC and STM32F398xE)

The I2S clock can be either the System clock or an external clock provided on I2S_CKIN pin. The selection of the I2S clock source is performed using bit 23 (I2SSRC) of RCC_CFGR register.

However, with the system clock configured to 72MHz, I still get the following error trying to set the audio frequency to 48kHz:

With this I2S Clock (8.0MHz), the divider value (0) is too low to obtain the desired Audio Frequency. The I2S Clock must be higher than (21.504 MHz).

Am I doing something wrong here, am I missing something, or is STM32CubeMX wrong on the clock speeds?

Thanks!

- David

[waclawek.jan]

> Am I doing something wrong here, am I missing something, or is STM32CubeMX wrong on the clock speeds?

Try to set it to a sample rate which would correspond to the 8MHz (i.e. 5.3kHz), compile and run it and check, what's the result.

Or dump Cube/CubeMX and write code on which you can rely.

JW