STM32 Unique ID register not so unique (Or, how to read docs properly)

UPDATE: This post is WRONG! See updated information here

The findings below were based on expecting the UID register to be contiguous as it is on all other STM32 parts. This is not true on the L1 family, and I hadn’t taken enough care with reading the reference manual.

Original post below


Following up from when I wrote about it earlier, it turns out that the “unique” id isn’t as unique as it is meant to be.

On my desk I have three different STM32L151C6T6 revision “V” parts, with exactly the same 96bit unique id. The parts all have package labels “GH254 VG” and CHN309

UID[32:0] (0x1FF80050) UID[63:32] (0x1FF80054) UID[96:64] (0x1FF80058)
Hex 0x0e473233 0×30343433 0x7b747800
Decimal 239546931 808727603 2071230464

According to reports on the irc channel ##stm32, this has also been seen (at least) on stm32f407vet6 parts.

Not fun :(

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