MjolnFileSystem

Author: Saurav Sajeev
Description: A file system designed for EEPROM storage management using AT24C series chips. Latest version: 1.0.0

---

Table of Contents

1. Overview
2. Supported EEPROM Models
3. Features
4. Installation
5. Usage
6. Command Set
7. API Reference
   • Initialization and Mounting
   • File Operations
   • File System Information
   • Terminal Interaction
8. Notes
9. Warnings
10. License

---

Overview

MjolnFileSystem is a lightweight, structured file system built for AT24C-series EEPROM chips. It provides functionality for file storage, retrieval, deletion, and system monitoring while optimizing memory usage. Designed for embedded systems, it allows efficient data management in constrained memory environments.

---

Supported EEPROM Models

The file system supports various AT24C EEPROM types, each with different storage capacities:

enum AT24CXType {
AT24C04 = 0x09, // 4 KB EEPROMAT24C08 = 0x0A, // 8 KB EEPROMAT24C16 = 0x0B, // 16 KB EEPROMAT24C32 = 0x0C, // 32 KB EEPROMAT24C64 = 0x0D, // 64 KB EEPROMAT24C128 = 0x0E, // 128 KB EEPROMAT24C256 = 0x0F, // 256 KB EEPROMAT24C512 = 0x10// 512 KB EEPROM
};

The correct EEPROM model must be selected when initializing the file system.

---

Features

• File Management: Create, read, update, delete, and list files stored in EEPROM.

• Storage Monitoring: Retrieve storage usage information, including percentage and bytes used.

• System Control: Print file system details, format EEPROM, and manage logs.

• EEPROM Formatting:

  • format(): Resets the boot sector and erases all data.
  • cleanFormat(): Erases all data without reflashing the boot sector.

• Serial Terminal Interaction: Execute commands via the serial interface for real-time file system management.

• Performance Optimization:

  • Efficient file caching.
  • Boot-time one time indexing which creates a lookup table for faster access.

---

Installation

1. Clone the Repository

git clone https://github.com/YOUR_USERNAME/MjolnFileSystem.git
cd MjolnFileSystem

2. Initialize and Mount the File System

MjolnFileSystem fs(AT24C32); // Initialize with chosen EEPROM modelif (!fs.mount()) {
fs.format(); // Format EEPROM if unrecognized
}

Ensure the correct EEPROM type is passed as a parameter.

---

Usage

Writing Data to a File

fs.writeFile("config", "settings123");

Reading Data from a File

char buffer[256]; // Allocate bufferuint32_t length = fs.readFile("config", buffer);
Serial.println(buffer);
delete[] buffer; // Free memory after use

Updating File Data

fs.updateFile("config", "newsettings456");

Deleting a File

fs.deleteFile("config.txt");

Listing Stored Files

fs.listFiles();

---

Command Set

The terminal() function supports various commands for file system interactions.

Command	Description	Example
mk <filename><data>	Create a file and write data	mk config.txt settings123
rm <filename>	Delete a specified file	rm config.txt
ls	List all available files	ls
read <filename>	Read a file's contents	read config.txt
update <filename><data>	Update a file's contents	update config.txt
info	Display file system information	info
delpart	Format EEPROM and erase data	delpart
storeuse	Show storage usage %	storeuse
storeusebytes	Show total used bytes	storeusebytes
defrag	Defragment the file system	defrag
exit	Exit the terminal session	exit

---

API Reference

Initialization and Mounting

MjolnFileSystem(AT24CXType eepromModel);
boolmount();

• Initializes the file system with the selected EEPROM model.
• Use format() before mounting if the EEPROM is unrecognized.

---

File Operations

boolwriteFile(constchar *filename, constchar *data);
uint32_treadFile(constchar *filename, char *buffer);
booldeleteFile(constchar *filename);
boolupdateFile(constchar *filename, constchar *data);
voidlistFiles();

• writeFile(): Creates and writes data to a file.
• readFile(): Reads file contents into a dynamically allocated buffer. Caller must free it.
• deleteFile(): Deletes the specified file.
• updateFile(): Updates the contents of a file, replacing any existing data.

/** * @brief Updates data in a file. * @param filename Name of the file to write to. * @param data Data to be written. * @return True if update operation is successful, false otherwise. * @note Overwrites existing content if the file already exists.*/boolupdateFile(constchar *filename, constchar *data);

---

File System Information

voidprintFileSystemInfo();
voidprintFileInfo(constchar *filename);
boolformat();
boolcleanFormat();
floatgetStorageUsage();
uint32_tgetBytesUsed();
voidshowLogs(bool show);

• Print file system and file-specific information.
• format() and cleanFormat() clear EEPROM data.
• getStorageUsage() returns the usage percentage.
• showLogs() enables or disables debug logs.

---

Terminal Interaction

voidterminal();

• Launches an interactive serial terminal for file operations and system management.

---

Performance Optimization

Internal File Lookup Cache

To enhance lookup speed, the following mechanism is used:

uint16_tMjolnFileSystem::findFileFromCache(constchar *filename)

• Searches filenames cached during initial boot.
• Reduces the need for repeated FAT scans.
• Applies a load-balancing strategy for efficiency.

Initial FAT Indexing

voidMjolnFileSystem::runInitialIndexingAndStore();

• Runs during boot to cache filenames into a list.
• Enables faster findFileFromCache() execution.
• Balances memory usage vs. lookup performance.

---

Notes

• Memory Management: Caller is responsible for freeing memory returned by readFile():

char* buffer = newchar[256];
uint32_t len = fs.readFile("config", buffer);
Serial.println(buffer);
delete[] buffer;

• File System Formatting: Use delpart or format() with caution; all data will be erased.

• Serial Communication: Ensure commands sent to terminal() are well-formatted.

---

Warnings

• FAT Entry Size Limitation: Filenames are limited to 8 characters due to a 16-byte FAT entry size. Exceeding this may cause file errors.

---

License

This project is licensed under the MIT License. You are free to use, modify, and distribute it for personal or commercial purposes.

---

Let me know if you'd like this converted into an actual `README.md` file or need further enhancements (e.g., diagram of internal architecture, example terminal session logs, etc.).