Query on operation of SAI in asynchronous slave mode

[Jansunil]

Hi Team,

I have a scenario where I am operating the SAI1_A peripheral in the Nucleo-L552ZEQ . The device is configured to be in asynchronous slave mode. The master device generates the SAI_FS, SAI_SCK and the SAI_SD signals. Could you please clarify on what would be the maximum frequency of the SAI_SCK signal generated from the master would be read by the STM32L55 IC? I see on the clock configuration tab that the SAI frequency has been set as 31.428MHz (which is the maximum I could configure). In my case, I could observe that I cannot read data for a clock frequency higher than 16MHz (any frequency at the SAI_SCK below 16MHz works perfect). Is it an expected behavior? or could there be any configurations missing on my end? Any leads on this would really be of help. Thanks in advance.

Regards,

Janani

[waclawek.jan]

How is your SAI clock set in RCC?

Although it's not needed to clock in data, it may still be needed to transfer data from the shift register to the APB-side data register.

JW

[Jansunil]

@Community member​ -Thank you for the support. Attaching a snap of the clock configuration window for your reference.

  

Thanks,

Janani

[LCE]

What is your channel and sampling rate setup?

Or what's the source chip, and its clocks?

[Piranha]

What's the problem with looking at the datasheet "Table 130. SAI characteristics"?

[Jansunil]

The source chip clock frequency is around 24.6MHz and the FS signal is around 500kHz

[LCE]

Okay, rather unusual sampling rate for an audio interface.

As Piranha says, checked the datasheet?

[Jansunil]

The datasheet says that the maximum value is 50MHz and the frequency set on my end seems to be well within the limit

[Jansunil]

The datasheet says that the maximum value is 50MHz for voltage range 0 (I see that the voltage control scaling has been configured to range-0) and the frequency set on my end seems to be well within the limit

[AScha.3]

your SAI clock is about 32 MHz ; ds says something about SAI min. clock > 2 x data clock;

so your max. data clk should be about 16 M.

-> set SAI module clock higher.... for 25M data , need 50M SAI clk.