FlashFile.h File Reference

High-level implementation of the file system implementation. More...

Go to the source code of this file.

Functions
uint32_t	OS_File_New (uint32_t buf[64])
	create new file More...
uint32_t	OS_File_Size (uint32_t num)
	file size new file More...
uint32_t	OS_File_Append (uint32_t num, uint32_t buf[64])
	append to existing file More...
uint32_t *	OS_File_Read (uint32_t num, uint32_t location)
	read from existing file More...
uint32_t	OS_File_Format (void)
	create new file More...

Detailed Description

High-level implementation of the file system implementation.

Runs on MSPM0G3507. One memory bank as MAIN memory. Each flash word is 8 bytes (64 bits). Each word line is 16 word lines, 128 bytes. Each sector 8 word lines, 1024 bytes (minimum erase size). There is one Bank on MSPM0G3507, with 128k bytes, 128 sectors. Once a byte has been programmed, it cannot be reprogrammed unless the sector is erased

Version

ECE445M RTOS V1.2

Author

Jonathan Valvano

Copyright

Copyright 2026 by Jonathan W. Valvano, valva.nosp@m.no@m.nosp@m.ail.u.nosp@m.texa.nosp@m.s.edu,

Warning

AS-IS

Note

For more information see http://users.ece.utexas.edu/~valvano/

Date

June 4, 2026

This solution is predicated on the assumption that erased flash will read as all 1's The data sheet says flash is indeterminate after erasing, but experimentation shows it as all 1's

After erasing

• File system is in Flash locations 0x10000 to 0x1FFFF (64k)
• Since MSPM0 has a simple way to write 64-bit data, all pointers are 64 bits
• Sector size is 1k (erase boundary), 64 sectors
• Block size is 256 bytes

• Write data size is 64 bits, 8 bytes, one flash word

  Directory/FAT are in last two sectors of Flash Rom
  

• Directory has 16 entries for file numbers 0 to 15 (16*8=128=0x80 bytes)
• FAT has 240 entries for blocks 0 to 239 (240 blocks each 256 bytes is 61,440 bytes
• 2 sectors for Directory/FAT leaving 62 sectors for data (63,488 bytes) (most of 64k Flash)
• Directory+FAT is (16+240) 64-bit values = 2048 bytes (last two sectors 0x1F800-0x1FFFF)
• Since directory/FAT are in ROM, they are always loaded, valid, and available