STM32MP157 Errata 2.3.8, "eMMC boot Timeout too short", causes problems with available eMMCs.

[SigiBue]

The STM32MP157 demands a maximum time of 10 ms from reset command to boot partition data. According to JEDEC No 84-B51 the maximum time from reset command to the first data is up to 1 second (tBD):

All data sheets of eMMCs that I found specify their boot timing according to the JEDEC spec.

I don't understand how I can ensure that eMMC boot works reliable for all devices.in the field. Can you please help me?

Do I understand it right or is there a solution available?

[PatrickF]

Hi @SigiBue​ ,

this limitation is present only on Rev.B devices and corrected on Rev.Z devices.

Rev.Z devices started production in beginning of 2020, so all recent devices you could purchases will follow JEDEC requirements.

Regards.

[SigiBue]

Thank you Patrick for your fast response.

It seems that we have left some boards with the old Rev B CPUs in the laboratory. I will throw them away to avoid further troubles.

[PatrickF]

They could work with some selected eMMC device (Toshiba or Kingston as listed in the Errata)

Regards.

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