nvblock is a small translation layer that provides block based access for non volatile memories (e.g. eeprom, nor-flash, nand-flash, ...). It is designed for usage on resource constrained systems. nvblock divides the non volatile memories in size-configurable blocks and provides standard read and write routines. It has the following features:
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Configurable block size: with a minimum of 32 bytes (or the write block size if this is bigger).
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Wear levelling: the erase of any two (non bad) blocks differ with atmost 1.
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Trim: blocks can be deleted when they are no longer to improve system performance
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Data integrity, write (and trim) of sectors are atomic, if during a write the power fails the system recovers to the last finished write (or trim).
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Support for bad blocks (optional for eeprom/nor flash, required for nand flash)
The nvblock author is gratefull to the developers of the dhara nand flash wear levelling library. Idea's from the dhara library (e.g. the radix tree) have been adapted in the nvblock library.
The minimum block size of 32 byte also imposes a limitation that is built into nvblock: the maximum number of blocks supported is limited to 2^16-1.
The implementation has almost no assumptions on the non volatile memory (hence the capability to support different kind of memory). The library can take advantage of hardware features if available, e.g.:
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Use internally buffered copy operation.
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The library consumes no OOB bytes if available.
The implementation requires the hardware routines to be provided. These
routines are documented in lib/nvblock.h as a nvb_config structure. More
specifically the hardware routines should provide:
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read, prog, move, comp (optional) routines. When working on non volatile memory that uses block erase, the prog and move routines should erase a block when a write is performed to the start of a eraseable block.
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is_bad/mark_bad routines for non volatile memory that needs bad block marking. Blocks marked bad will not be erased nor will they ever be used again for writing.
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is_free routine to determine wether a block is free.
For zephyr users the library provides support for nor-flash devices as a zephyr
module. This module can be enabled by adding it to example.yaml in the
submanifest folder as:
manifest:
projects:
- name: nvblock
url: https://github.com/Laczen/nvblock
revision: main
After west update the module should be available and can be found as nvblock
in the local workspace.