Parsing UID Fields on STM32L476 – Wafer X/Y Coordinates and BCD Encoding?

[robert-kau]

Hi everyone,

I’m working with an STM32L476 and need to parse its 96-bit Unique Device ID (UID).
According to RM0351, the UID starts at address 0x1FFF 7590.

Reading that region with STM32CubeProgrammer gives:

• 0x1FFF 7590 : 0x004A0029
• 0x1FFF 7594 : 0x58335011
• 0x1FFF 7598 : 0x2031374B

So the full UID (high → low) is 0x2031374B 58335011 004A0029.
According to this documentation, the lower 32 bits encode the X/Y coordinates of the die on the wafer, in BCD.

That leaves two questions:

1. Bit mapping

   • Which 16-bit half-word is X and which is Y?

   • Is it X = bits [31:16] and Y = bits [15:0], or the other way around?

2. BCD validity

   • If the field is pure BCD (8421), every nibble should be 0-9, yet the value 0x4A contains nibble A (10).

   • Do recent STM32 parts still use BCD for these coordinates, or should those half-words be treated as plain unsigned integers?

Any clarification or official reference would be greatly appreciated.

Thanks!

[mƎALLEm]

Hello,

I can answer the first question,

According to this thread: STM32H7A3 Unique Device ID number question 

X = bits [15:0]  and Y = bits [31:16], I can check.

Meanwhile, I will try to check internally for the format of X/Y and get back to you if I get the information.

[mƎALLEm]

Hello,

I've got a confirmation internally regarding question 1: indeed X = bits [15:0]  and Y = bits [31:16].

For the second question you need to an online support request over this link. 

Thank you