topic Re: MCX A secure/signed mode in rom bootloader? in MCX Microcontrollers

MCX A secure/signed mode in rom bootloader?

dav1 — Tue, 10 Feb 2026 12:26:14 GMT

Lets assume we want to design a system using MCX A-series that uses the ROM bootloader feature for end-customer firmware upgrades.

Upgrades could happen via web-serial->usb or in-system updates via UART from another mcu, both talking directly to the rom boot code.

I haven't looked in detail whats available in the newer MCX-series rom implementation, but the questions are:

is there a way to require a signed binary when using ROM boot?
- i.e. write "otp-keys" to flash and force the bootloader to only accept valid binaries to be written
are there ways to prevent raw reads from flash while still having erase/write enabled?

in my case mcu pick would be: MCXA156VPJ

ps. fully aware I can write my own 2nd stage BL to achieve this, but the whole point here is to design a simple + brick-proof system.

Alice_Yang — Wed, 11 Feb 2026 09:23:11 GMT

Hello @dav1

The MCXA series does not support secure or signed mode in the ROM bootloader.
Please consider using the MCXN series, which does support this feature.

Thank you.

Alice

dav1 — Wed, 04 Mar 2026 14:32:49 GMT

the N-series are too expensive for the application.
what other mcx'es do support secure rom-boot?

are you 100% sure there isn't a way to achieve a secure update-path on A-series?