https://github.com/peterhinch/micropython_data_to_py

A Python3 utility to convert an arbitrary binary file to Python source for storage in Flash
https://github.com/peterhinch/micropython_data_to_py

Last synced: 2 months ago
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A Python3 utility to convert an arbitrary binary file to Python source for storage in Flash

• Host: GitHub
• URL: https://github.com/peterhinch/micropython_data_to_py
• Owner: peterhinch
• License: mit
• Created: 2017-03-03T11:55:22.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2023-08-01T09:04:45.000Z (11 months ago)
• Last Synced: 2024-01-28T08:36:36.822Z (5 months ago)
• Language: Python
• Size: 3.91 KB
• Stars: 25
• Watchers: 3
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Lists

• awesome-micropython - micropython_data_to_py - A Python 3 utility to convert an arbitrary binary file to Python source for freezing as bytecode in Flash. (Libraries / Storage)

README

        
# data_to_py.py

A means of storing read-only data in Flash, conserving RAM.

The utility runs on a PC and converts an arbitrary binary file into a Python

source file. The generated Python file may be frozen as bytecode. Read-only

data may thus be stored in Flash and accessed with little RAM use.

Please see also [freezeFS](https://github.com/bixb922/freezeFS) - a utility by

@bixb922 which allows a complete directory tree to be frozen and mounted as a

filesystem.

## Arguments

The utility requires two arguments, the first being the path to a file for

reading and the second being the path to a file for writing. The latter must

have a ``.py`` extension. If the output file exists it will be overwritten.

## The Python output file

This instantiates a ``bytes`` object containing the data, which may be accessed

via the file's ``data()`` function: this returns a ``memoryview`` of the data.

The use of a ``memoryview`` ensures that slices of the data may be extracted

without using RAM:

```python

import mydata  # file mydata.py (typically frozen)

d = mydata.data()  # d contains a memoryview

s = d[1000:3000]  # s contains 1000 bytes but consumes no RAM

```

A practical example is rendering a JPEG file to an LCD160CR display. The Python

file ``img.py`` is generated using

```

$ ./data_to_py.py my_image.jpg img.py

```

The file ``img.py`` may then be frozen, although for test purposes it can just

be copied to the target. The following code displays the image:

```python

import lcd160cr

import img

lcd = lcd160cr.LCD160CR('Y')

lcd.set_orient(lcd160cr.PORTRAIT)

lcd.set_pen(lcd.rgb(0, 0, 0), lcd.rgb(0, 0, 0))

lcd.erase()

lcd.set_pos(0, 0)

jpeg_data = img.data()

lcd.jpeg(jpeg_data)  # Access the data and display it

```

## Validation

The utility can accept any file type as input, so no validation is performed.

If required, this must be done by the application at runtime. For example in

the above code, to be suitable for the device jpeg_data[:2] should be

``0xff, 0xd8`` and jpeg_data[-2:] should be ``0xff, 0xd9``.