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Associate II
May 29, 2024
Question

How to use STM32H7's UID(96bits) to generate 3 bytes for Mac address?

I need generate ethernet Mac address for my devices(STM32H7xx), and want to make those devices' Mac address NOT same. The first 3 byte of Mac address will use ST's, so only leave 3 bytes. 

We want to use the chip UID to generate the 3 bytes of the Mac address. What is the best way for us to generate them? 

I dont know what is the meaning of 3 parts(HAL_GetUIDw0/1/2) of UID, I found most parts of our chip's UID are same, just a few chars are different, dont know if we can ignore some of UID which are almost not changed. 

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3 replies

Tesla DeLorean
Guru
May 29, 2024

ST is not providing you with 16 million MAC addresses, you'll need to BUY and serialize your own.

There's wafer batch, and die X / Y position data. There's not really any guarantee you can shrink the 96-bit UID into a 24-bit one.

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HarryXiaAuthor
Associate II
May 30, 2024

so HAL_GetUIDw0 of UID is wafer batch, right?

Tesla DeLorean
Guru
May 30, 2024

I'm not sure of the exact mappings, I think there was a White Paper at one point, and other posts to the forum.

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