STM32MP157AAA3 use LPDDR3?

[Mokail]

I designed a PCB using LPDDR3 and STM32MP157AAA3 MPU, but I accidentally found that u does not support, this is not a pit man? Why is this diagram on the DDR instruction manual AN5122, I'm designing it accordingto this. But now pcb has produced how to solve this problem?

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@st

[PatrickF]

Hello,

I agree that there is a mistake in AN5122, but note that LPDDR2/LPDDR3 are not supported on LFBGA packages (STM32MP15xAA and xAB) mostly because all signal integrity simulation have not been done. This was mostly because market analysis was not showing use cases with LFBGA pitch 0.8 (mainly for industrial market and/or low cost PCB) and LPDDR (higher price, smaller PCB size, low power).

From IC point of view, nothing avoid to use LPDDR2/LPDDR3 with LFBGA package, but you should confirm signal integrity on your side as we did not provide any golden routing example nor support in CubeMx tool configuration.

Once you have a uBoot SPL basic boot running, I think the CubeMx DDR tuning tool could work if you fake it during tests by using another package supporting LPDDR.

Hope this help.

[Mokail]

Hello,​

Thank you very much for your answer, that is to say, in fact, the chip itself is supported right? Just do we need to debug the parameters?because my pcb is currently using lpddr3, if the redesign is very troublesome.:face_screaming_in_fear: :face_screaming_in_fear: :face_screaming_in_fear:

[PatrickF]

Yes, same chip is used in all packages, only less signals made available.

[Mokail]

Ok..Thanks a lot.

But when i used the tool for my board,i don't kown why its can't connect,the -boot-spi in sysram

[PatrickF]

To Connect, you need to have a running uBoot SPL (basic boot) on your board (i.e. boot from a Flash or SD-Card).

If not, you should use SYSRAM loading to get it running and connect USB (FlashProgrammer is used to load it in SYSRAM instead of loaded from Flash)

You could refer to https://wiki.st.com/stm32mpu/wiki/U-Boot_SPL:_DDR_interactive_mode and CubeMX User Manual (see 'DDR Suite' section)

[Mokail]

Yes,it's look great:face_with_tears_of_joy: :face_with_tears_of_joy:

but abort tuning the process is slowly?:fearful_face: