333e16521b
Includes an introduction to using the Zephyr port on MicroPython. The quickref details examples of how to use each module the port currently supports. The tutorial provides additional details for Zephyr specific modules. Signed-off-by: Julia Hathaway <julia.hathaway@nxp.com>
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 `uos Filesystem Mounting <https://docs.micropython.org/en/latest/library/uos.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 `uos.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 `uos.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.
|