SEPTEMBER 7, 2026

N3S

Bare Metal ProgrammingC ProgrammingEEPROM FilesystemGraphics LibraryCommunication ProtocolCLI
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N3S - Nano-Scale Sub-Systems

  • N3S stands for Nano-Scale Sub-Systems. It combines a custom EEPROM Filesystem (NSFS), Display Library (NSD) and Communication Protocol (NSP), along with a CLI tool to interact with the system from Linux PC (NSCLI). (Fun fact: N3S sounds like entrées showing the nature of the project being made of entrée-esque subsystems).
  • Project itself is meant for improving my skills in embedded/constrained environment C firmware development, systems engineering, writing portable code and modular software architecture.
  • Every subsystem has each of these modular layers below designed and implemented manually (Inspired by the book Reusable Firmware Development by Jacob Beningo).

API Architecture from Beningo's book

# NSFS - Nano-Scale Filesystem
  • NSFS subsystem implements a custom filesystem on an EEPROM with 4 file types. It contains 4 modules that progress in abstraction. modules for slots and files are completely abstracted from hardware specific code and can be ran on any MCU with very few tweaks.

Statistics

  • Efficiently uses 96.9% of raw EEPROM bits meaning minimal waste.
  • Lets users access and modify 89.06% of the raw EEPROM bits.
  • Can store files up to 7.296KB in size.
  • Allows up to 256 possible files

Modules

Module Responsibility
i2c.h Low-level I2C driver for MCU–EEPROM communication
eeprom.h EEPROM read/write HAL built over I2C
slot.h Hardware-independent filesystem middleware: headers, metadata, slot tables, and data mapping
file.h File API; represents files as ordered slots within a section

File types

  • Text (.t) - Read ASCII text
  • Executable (.e) - GPIO manipulation with custom timing
  • Vector (.v) - Draw vector shapes
  • Bitmap (.i) - Render bitmap images

NSD - Nano-Scale Display

Modules

Module Responsibility
spi.h Low-level SPI driver for MCU–OLED communication
oled.h OLED initialization, SPI commands, software framebuffer, hardware abstraction
gfx.h Coordinate-based graphics API for shapes and ASCII text
ui.h UI primitives: properties, buttons, loading screens, etc.
menu.h Superloop-controlled menus combining UI with other subsystem APIs

Shapes and Text

Shapes

  • Dots: Literal pixels
  • Lines: Bresenham’s Line Algorithm implementation
  • Rectangles: By diagonal line's endpoints
  • Triangles By 3 vertices

Text

  • Rendering a 5x8 ASCII font defined in font.h
  • Character composition into strings

NSP - Nano-Scale Protocol

NSCLI - Nano-Scale Command Line Interface