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)|
According to reports on the irc channel ##stm32, this has also been seen (at least) on stm32f407vet6 parts.
Not fun :(