Can L9788 be interfaced to a microcontroller via SPI?

AlxCrt · ‎2025-08-29

Hello all,

this post just to know if the L9788 Automotive Engine Management System IC can be interfaced to a microcontroller via SPI instead of MSC bus (single ended interface instead of differential one).

Thanks a lot,

Regards.

AC.

Andrew Neil · ‎2025-08-29

Surely, the datasheet would tell you that?

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.

Peter BENSCH · ‎2025-08-29

Welcome @AlxCrt, to the community!

The MSC is an asymmetric bus, see also here.

Perhaps MSC could be replicated with two SPI and some gluelogic, but I am not aware of any such implementation. But why emulate it when there are MCUs that have this interface natively?

Regards
/Peter

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AlxCrt · ‎2025-08-29

Thank you so much Peter for your answer,

"But why emulate it when there are MCUs that have this interface natively?"

because I must use a microcontroller that doesn't have MSC bus properly "natively" it has the MSC support by one specific mode of the DSPI unit, so since the driver for the SPI is just ready and the MSC driver should be written, I made the question just to save time in case.

I know there are other chips that permit to interface with SPI or MSC that is why I asked you.

PS. I know Infineon implement MSC bus natively on some microcontroller, which ST's Automotive microcontroller implement it natively?

Regards,

AC.

mƎALLEm · ‎2025-08-29

Hello,

Please refer to this Eval board: EVAL-L9788 its using SPC563M64L automotive MCU.

I don't have idea about the MSC interface but according to the schematics of the previously mentioned Eval board:

It shows the following (last page):

May be you need to look at this direction.

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Peter BENSCH · ‎2025-08-29

Many SPC5x MCUs provide MSC (Microsecond Bus).

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AlxCrt · ‎2025-08-29

Hi mƎALLEm,

thanks for your reply, I just have that evalution board (EVAL-L9788) but from the documentation I have (EVAL-L9788 hardware documentation), there wasn't the last page!! so I had seen the signals SPI_CLK, SPI_DO and SPI_DIN that dead on the interface connector, but the image you attached show clearly that SPI signals goes to L9788 chip!!

This give me a chances, but may be to use the SPI connection, there is a pin on the L9788 that must be connected to GND or VDD to select that type of interface(may be some differential pin that is not used in single ended SPI mode)...anyway should this work, it is an undocumented feature, do you know how can I reach someone who know the truth on this matter?

Thanks a lot for giving me this hope!

Regards,

AC.

mƎALLEm · ‎2025-08-29

@AlxCrt wrote:

do you know how can I reach someone who know the truth on this matter?

AC.

I think better either to contact your local ST sales or file an online ticket over OLS: https://ols.st.com/

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