Showing results for 
Search instead for 
Did you mean: 

STM32U5A5: LQFP64 (STM32U5A5RJT6Q) - SAI2_SD_A, SAI2_SD_B - why not available?


I could cry... ("rrrr", the more I dive into latest STM MCUs - the more I get frustrated - LOL)

The datasheet for STM32U5A5, LQFP64 package, tells me: there are PB15 as SAI2_SD_A and also PC12 as SAI2_SD_B.

But the CubeMX does not let me configure these signals as SAI2: I need just one pin (one of them, preferred as PB15 = SAI2_SD_A, for a S/PDIF output).


  • if I load and see the features of this STM32U5A5, LQFP64 package in CubeMX:
    it tells me just SAI = 1
    - it is actually not true: the datasheet shows me a complete signal set "possibility" for SAI2 as I2S!

    - SAI2_A and SAI2_B are complete on the STM32U5A, even for this package!
  • if I try to configure pins, e.g. PB15 as SAI2_SD_A, or PC12 = SAI2_SD_B:
    the SAI2 features for these pins are not there (not in list) - using CubeMX

Is this a "bug" in the CubeMX tool? (I hope so!)
based on datasheet - still possible to use SAI2 and one pin as SAI2_SD_A or SAI2_SD_B as a S/PDIF output?
How to generate code for SAI2_SD_x as S/PDIF output? (assuming, changing to a different package just for code generation).
Assuming (hoping) just the CubeMX software is wrong - but the chip has a complete SAI2.

It is very confusing: the datasheet tells me something which is not correctly reflected in CubeMX.

Dear STM team:

  • is there an SAI2 available in STM32U5A5 LQFP64 package? (I think so, or your datasheet would be so wrong)
  • can I use SAI2_SD_A (PB15) or SAI2_SD_B (PC12) still for S/PDIF Tx?
    (even your CubeMX does not "allow" me to configure - reporting this issue here also as a "bug")

even not working yet (SPDIF on SAI2_B) - I think the HAL driver has an issue to configure the SPDIF clock properly.
(a separate thread following)