SimpleOS

A minimalist and modular operating system built from scratch for the ATmega328P

SimpleOS is a lightweight, low-level operating system designed specifically for the ATmega328P microcontroller, created entirely from scratch without using the Arduino framework or standard libraries. Its main goal is to provide developers with a flexible and efficient environment for embedded programming, using a structured and object-oriented approach in C++.

The system is composed of independent modules, including:

• A custom thread execution system using hardware timers and the watchdog.
• A virtual RAM section tracker for memory diagnostics.
• Native support for UART and I2C communication interfaces.
• A modular namespace-based architecture, enabling better organization and scalability.
• A custom type system (Number<T>, List<T>, etc.) and utility concepts to abstract low-level operations.

SimpleOS is ideal for educational purposes, hobbyist microcontroller projects, and for developers who want to explore how to design an OS-level system from the ground up on constrained hardware.

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V0.4.00 - Communication system update

UART:

• Implemented byte read interrupt routine with 64 byte virtual input buffer.

I2C:

• Implementation of the send and receive methods.

Organization and Architecture:

• Some classes have been moved to the Instance namespace, which contains instances of system dependencies.

V0.3.11 - Pinning system refactoring

Hardware:

• Removed GPIO class.

V0.3.10 - I2C Update

I2C:

The Core library of I2C (TWICore.h) was developed.

Organization and Architecture:

• Namespace Time has been added.

Utils:

• The IsPrimitive operator checks whether the data type is primitive or not.

Notes:

• TypeOf operator has been enabled.

Additions:

• Core:
  • TWICore.h
• Utils:
  • IsPrimitive.h

V0.3.00 - Threads Update

Thread and Interrupts

A library of thread executors was developed that work from the interrupts generated by Watchdog and TIMER0. Through the Executors.h library, it is possible to choose which executor the thread will be assigned to.

RAM

A RamInfo.h library was developed that contains status information of each RAM subsection.

• BssSection.h: Get status information from BSS section.
• DataSection.h: Get status information from Data section.
• HeapSection.h: Get status information from Heap section.
• StackSection.h: Get status information from Stack section.

Organization and Architecture:

• Namespace Native has been renamed for Core.
• Namespace Error has been added.
• Namespace Handler has been added.
• The Ticks.h class has been renamed to Counter.h
• The macros were divided into 4 files
  • HardwareMacros.h
  • SyntaxMacros.h
  • SystemMacros.h
  • UtilityMacros.h

Notes:

• TypeOf operator has been disabled.

Additions:

• Concepts:

  • Identifiable.h
  • Printable.h

• Core:

  • TMR0Core.h
  • ResetCore.h
  • ResetType.h

• String

  • SimpleString.h

• Interrupts

  • Timer0.h
  • Executors
    • Executors.h
    • ThreadExecutor.h
    • TimerExecutor.h
    • WatchdogExecutor.h

• RAM

  • RamInfo.h
  • Sections
    • DataSection.h
    • BssSection.h
    • HeapSection.h
    • StackSection.h

• Threads

  • Thread.h

• SystemStatus

  • ErrorCode.h
  • Status.h

• Counter

  • Counter.h

Removals:

• String
  • String.h
• Concepts
  • Default.h (Default concept)
• Managers:
  • MemoryManager.h
  • TaskManager.h
  • ThreadManager.h
• Task:
  • Task.h
  • TaskAdapter.h
  • TaskController.h
  • TaskProperties.h
  • TaskLifecycle.h
  • TaskState.h
• RamAllocator:
  • Heap.h
  • RamAllocator.h

V0.2.00 - System Types Update

Organization and Architecture:

• Namespace Operators has been renamed for Utils.

System:

• The standard heap memory size of the system has been increased to 384 addresses (768 bytes).

Types added:

• List<T>
• ArrayList<T>

Types:

• Decrement, increment and bitwise operators have been implemented in the Number<T> class
• The LinkedList<T> and ArrayList<T> classes implement List <T>.

Typedefs changes:

• C_string has been changed to CString.
• Hashcode alias removed.
• Alias of primitive types were changed to class Number <T>.

Alias	Type
Char	Number<char>
UChar	Number<unsigned char>
Int	Number<int>
UInt	Number<unsigned int>
Long	Number<long>
ULong	Number<unsigned long>
Float	Number<float>
Double	Number<double>
Bool	Number<bool>

Others:

• The Operator << (Const String & Data) is temporarily removed from the UART class for optimization.
• UART now prints boolean types.

Notes:

• A bug was identified in the malloc method of the RamAllocator class. It will be fixed in the next updates.

V0.1.02 - Code Refactoring

• System macro removed: conceptualize
• The System class now inherits from the GPIO class.

V0.1.01 - Code Refactoring and Project Reorganization

• Methods class creation.
• The System class now inherits from the Watchdogtimer class.
• The System class now inherits from the Methods class.
• Person.h test class was removed.
• Addition of comments on the code.
• SimpleOS folder name change to System.

V0.1.00 - Watchdog Timer Update

• Creation of the WatchdogTimer class. WDTCore optimization and refactoring of the Ticks class.
• Creation of Macro INT(vector) to handle interrupts
• Implementation of the Bootable and Executable concepts in the System class

Removed classes:

• MemoryHelper
• Interrupts.h
• VirtualRAM.h

Concepts created:

• Bootable
• Executable