Some bootloaders can be really simple. Here is one I wrote recently for my security key product (this particular code is for an ARM M3). https://github.com/So

Some bootloaders can be really simple. Here is one I wrote recently for my security key product (this particular code is for an ARM M3). https://github.com/SoloKeysSec/solo/blob/master/targets/efm32boot/src/main.c https://github.com/SoloKeysSec/solo/blob/master/targets/efm3... https://github.com/SoloKeysSec/solo/blob/master/targets/efm32boot/src/boot.c https://github.com/SoloKeysSec/solo/blob/master/targets/efm3... Like what others mention, it really depends on documentation from the vendor for the chipset you're working with. I mainly copied and pasted code from a form post by the vendor. And of course link to the security key product :) https://solokeys.com/ https://solokeys.com/