trezor-firmware/docs/core/src/index.md

Trezor Core

Trezor Core uses MicroPython, it is a Python implementation for embedded systems, which allows us to have an application layer in Python, which makes the code significantly more readable and sustainable. This is what you find in the src folder.

Not everything is in Python though, we need to use C occasionally, usually for performance reasons. That is what embed/extmod is for. It extends MicroPython's modules with a number of our owns and serves as a bridge between C and Python codebase. Related to that, mocks contain Python mocks of those functions to improve readability and IDE functioning.

Boot

Module src/main.py is the first one to be invoked in MicroPython. It starts the USB, initializes the wire codec and boots applications (see Apps).