57 lines
2.8 KiB
ReStructuredText
57 lines
2.8 KiB
ReStructuredText
.. _storage_zephyr:
|
|
|
|
Filesystems and Storage
|
|
=======================
|
|
|
|
Storage modules support virtual filesystem with FAT and littlefs formats, backed by either
|
|
Zephyr DiskAccess or FlashArea (flash map) APIs depending on which the board supports.
|
|
|
|
See `os Filesystem Mounting <https://docs.micropython.org/en/latest/library/os.html?highlight=os#filesystem-mounting>`_.
|
|
|
|
Disk Access
|
|
-----------
|
|
|
|
The :ref:`zephyr.DiskAccess <zephyr.DiskAccess>` class can be used to access storage devices, such as SD cards.
|
|
This class uses `Zephyr Disk Access API <https://docs.zephyrproject.org/latest/reference/storage/disk/access.html>`_ and
|
|
implements the `os.AbstractBlockDev` protocol.
|
|
|
|
For use with SD card controllers, SD cards must be present at boot & not removed; they will
|
|
be auto detected and initialized by filesystem at boot. Use the disk driver interface and a
|
|
file system to access SD cards via disk access (see below).
|
|
|
|
Example usage of FatFS with an SD card on the mimxrt1050_evk board::
|
|
|
|
import os
|
|
from zephyr import DiskAccess
|
|
bdev = zephyr.DiskAccess('SDHC') # create block device object using DiskAccess
|
|
os.VfsFat.mkfs(bdev) # create FAT filesystem object using the disk storage block
|
|
os.mount(bdev, '/sd') # mount the filesystem at the SD card subdirectory
|
|
with open('/sd/hello.txt','w') as f: # open a new file in the directory
|
|
f.write('Hello world') # write to the file
|
|
print(open('/sd/hello.txt').read()) # print contents of the file
|
|
|
|
|
|
Flash Area
|
|
----------
|
|
|
|
The :ref:`zephyr.FlashArea <zephyr.FlashArea>` class can be used to implement a low-level storage system or
|
|
customize filesystem configurations. To store persistent data on the device, using a higher-level filesystem
|
|
API is recommended (see below).
|
|
|
|
This class uses `Zephyr Flash map API <https://docs.zephyrproject.org/latest/reference/storage/flash_map/flash_map.html#>`_ and
|
|
implements the `os.AbstractBlockDev` protocol.
|
|
|
|
Example usage with the internal flash on the reel_board or the rv32m1_vega_ri5cy board::
|
|
|
|
import os
|
|
from zephyr import FlashArea
|
|
bdev = FlashArea(FlashArea.STORAGE, 4096) # create block device object using FlashArea
|
|
os.VfsLfs2.mkfs(bdev) # create Little filesystem object using the flash area block
|
|
os.mount(bdev, '/flash') # mount the filesystem at the flash storage subdirectory
|
|
with open('/flash/hello.txt','w') as f: # open a new file in the directory
|
|
f.write('Hello world') # write to the file
|
|
print(open('/flash/hello.txt').read()) # print contents of the file
|
|
|
|
For boards such as the frdm_k64f in which the MicroPython application spills into the default flash storage
|
|
partition, use the scratch partition by replacing ``FlashArea.STORAGE`` with the integer value 4.
|