Intro

Quick reference notes collected while working on embedded systems, backend services and developer tooling. Every page is organised the same way: the commands and settings used most often come first, background explanations and edge cases come last.

Pages

Page	What it covers
Git	Everyday branch, tag and upstream workflows
Linux	System admin, packages, networking, SSH, commands, TLS
Tools	IDE setup, shortcuts and known issues
Python	Environments, common commands, notable libraries
Java	Arthas diagnostics for running JVMs
Spring Boot	Configuration, security, OAuth 2.0, Flyway, REST design
Database	PostgreSQL, MariaDB, MongoDB, Redis, SQLite, access control
C++	MSYS2 + CMake toolchain on Windows, compiler flags
ESP32	Boards, AT firmware, Arduino projects, signed OTA
CMSIS	CMSIS-RTOS2 kernel API notes
STM32 MCU	Cortex-M: startup, clocks, MPU, cache, interrupts, flash, boards
STM32 MPU	Cortex-A (STM32MP): boot chain and OpenSTLinux Yocto
Electronics	Memory types, PLL, serial bus comparison
Algorithm	Data-flow problems such as FIFO underrun
Security	PKI, code signing, SignServer and EJBCA

Conventions

• Shell blocks are POSIX sh unless the block states otherwise.
• Placeholders are written in upper case, for example BRANCH_NAME.
• Values that depend on the specific MCU or board are called out explicitly; always confirm them against the reference manual for your part.