mimxrt — functionality specific to NXP i.MXRT

The mimxrt module contains functions and classes specific to the NXP i.MXRT family of microcontrollers.

Classes

class mimxrt.Flash

Get the singleton object that exposes the user-storage region of the on-board QSPI flash as a vfs.AbstractBlockDev-compatible block device. Block numbers are relative to the start of that region, not the physical start of flash.

In most cases, to store persistent data on the device, you’ll want to use a higher-level abstraction – for example the filesystem via Python’s standard file API. This interface is useful to customise the filesystem configuration or implement a low-level storage system for your application.

The object also implements the buffer protocol, allowing read-only memory-mapped access to the entire flash storage region via the QSPI XIP base. This makes a zero-copy view of the region available without issuing any flash reads:

flash = mimxrt.Flash()
view = memoryview(flash)
magic = bytes(view[:4])      # read the first 4 bytes directly from XIP

The block size used by the underlying flash sectors can be queried at runtime with ioctl(5, 0).

readblocks(block_num: int, buf: bytearray) → None

readblocks(block_num: int, buf: bytearray, offset: int) → None

Read bytes from the flash into buf. Two overloads expose the simple and extended interfaces:

Simple form (readblocks(block_num, buf)): reads whole blocks starting at block index block_num. len(buf) must be a multiple of the flash block size.

Extended form (readblocks(block_num, buf, offset)): reads len(buf) bytes – not necessarily a whole number of blocks – starting at byte offset within block block_num. len(buf) has no alignment constraint.

writeblocks(block_num: int, buf: bytes) → None

writeblocks(block_num: int, buf: bytes, offset: int) → None

Write bytes from buf to the flash. Two overloads expose the simple and extended interfaces:

Simple form (writeblocks(block_num, buf)): writes whole blocks starting at block index block_num. len(buf) must be a multiple of the flash block size. Each affected block is erased automatically before being written.

Extended form (writeblocks(block_num, buf, offset)): writes len(buf) bytes – not necessarily a whole number of blocks – starting at byte offset within block block_num. len(buf) has no alignment constraint, and no implicit erase is performed – the caller must ensure the affected blocks have been erased via a prior ioctl(6, block_num) call.

Raises OSError if the underlying flash erase or write operation fails.

ioctl(cmd: int, arg: int) → int | None

Standard vfs.AbstractBlockDev ioctl entry point. See vfs.AbstractBlockDev.ioctl() for the full list of cmd values. cmd=5 returns the flash block size in bytes; cmd=6 erases the block with index arg.