This is a simplified version of the Nexmon Framework by Daniel Wegemer and Matthias Schulz (https://github.com/seemoo-lab/nexmon)

I presented in 2018 at DEFCON how to use the Nexmon framework to modify Xiaomi firmwares, which are based on Marvel or Mediatek Cortex-M chips. You find the presentation here: http://dontvacuum.me/talks/DEFCON26-IoT-Village/DEFCON26-IoT-Village_How_to_Modify_Cortex_M_Firmware-Xiaomi.html

This release does not contain the buildtools, please download them from the nexmon repository.

Steps:

import folder buildtools from (https://github.com/seemoo-lab/nexmon/tree/master/buildtools)
source setup.env.sh
Maybe: cd buildutils/ and make
Edit: patches/common/wrapper.c to add more firmware functions (see blinkenlights)
Edit: patches/mw300/1/demo/src/patch.c to add new code to your firmware
Edit: firmwares/mw300/1/definitions.mk to define where new patches have to go