nRF54L15: OTP region in RRAMC remains erasable (NCS v3.2.0)

RE: nRF54L15: OTP region in RRAMC remains erasable (NCS v3.2.0)

zwq — Mon, 09 Feb 2026 03:40:41 GMT

Thanks for the clear explanation.That really clears up the confusion regarding the 'OTP' naming. Understanding that it's eraseable via a full device erasure (ERASEALL) and behaves like the rest of UICR is very helpful for our development on nRF54L15

RE: nRF54L15: OTP region in RRAMC remains erasable (NCS v3.2.0)

zwq — Mon, 09 Feb 2026 03:37:40 GMT

Thanks for clarifying the relationship between OTP and ERASEALL. It helps a lot for our security implementation on nRF54L15!

RE: nRF54L15: OTP region in RRAMC remains erasable (NCS v3.2.0)

Susheel Nuguru — Sun, 08 Feb 2026 16:04:37 GMT

ah, did not see Emil already replied with a really good answer before I replied.

RE: nRF54L15: OTP region in RRAMC remains erasable (NCS v3.2.0)

Susheel Nuguru — Sun, 08 Feb 2026 16:03:31 GMT

Hi,

I see the confusion, the OTP region is in the UIICR is write once per Erase all cycle, it is not a permanent fuse into the memory. We should make that clear in the documentation. Nordic solutions does not support an irreversible memory writes at all conditions. The chip still can be erased if they get debug access to the chip. If you lock the debug access using APPROTECT/SECUREAPPPROTECT then no one can erase the chip. These two features combined should give you a proper OTP like feature.

RE: nRF54L15: OTP region in RRAMC remains erasable (NCS v3.2.0)

Emil Lenngren — Sat, 07 Feb 2026 15:12:13 GMT

I agree that the name OTP is terrible here since it is actually eraseable. My colleague as well as nordic's AI (at least previously) were super convinced that it was impossible to erase it, due to the name OTP.

There is nothing special with the OTP registers compared to the rest of UICR. That is, you may write to it, but it can only be erased together with a full device erasure (via ERASEALL). You cannot erase an individual word.