How to read and write files on RaspberryPi Pico series ~ MicroPython ~

Introduction

This blog post explains how to use MicroPython to read and write files on the Raspberry Pi Pico series.

The MicroPython firmware allows you to use a virtual file system and powerful Python functions to read and write files just like you would on a regular computer (CPython).

No special configuration or equipment is required, so we hope you will find it useful for your projects, including log output and configuration files.

Environment

The environment used in this blog post is the following.

Connection with RaspberryPi Pico series

The Pico series can be used by itself.

Parts in use

Ready-to-use kits are also available.

Ready to use kits with soldered headers, USB cable and pin layout chart are also available.

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Programme overview

Results of running the program

The following is the result of running the program described below.

A text file named “pico.txt” is created inside Pico, and its contents are displayed as read into Thonny’s shell.

If the file does not appear when you run it,
Try clicking the “Refresh” button in the settings.

Entire code

The full text of the Code is as follows. The details are explained in the section “Key Points of the Code” below.

import os

# Specify a filename.
fileName = "pico.txt"

# Open the file in write mode
f = open( fileName,  "w")

# Write content
f.write("Raspberry\n")
f.write("Pi\n")
f.write("Pico 2\n")

#  Closes the file when writing is complete.
f.close()

# Reopen the file in read mode
f = open(fileName, "r")

# Line by line reading and display.
print( f.readline() )
print( f.readline() )
print( f.readline() )

# Closes file after writing.
f.close()

Key Points of the Code

Write and save files

The open function is used to write and save a file.

By specifying “w” for write and a file name as arguments, a text file is opened in “write mode” (if the file does not exist, a new file is created).

After opening, specify the string to write as an argument to the write function.
Since line feeds are not inserted, specify the string with “\n” at the end of the sentence or other places where you want to insert line feeds.

Calling the close function finishes writing and saves the file.

# Open the file in write mode
f = open( fileName,  "w")

# Write content
f.write("Raspberry\n")
f.write("Pi\n")
f.write("Pico 2\n")

#  Closes the file when writing is complete.
f.close()

Loading Files

The open function is also used to read a file.

Specifying “r” for read and the name of the file will open a text file in read mode.

Once opened, the text in the file can be read line by line using the readline function.

As with writing, when you are done reading, close the file with the close function.

# Reopen the file in read mode
f = open(fileName, "r")

# Line by line reading and display.
print( f.readline() )
print( f.readline() )
print( f.readline() )

# Closes file after writing.
f.close()

Finally

This blog post explains how to use MicroPython to read and write files on the Raspberry Pi Pico series.

As mentioned above, MicroPython formware allows you to read and write files on the Pico just like you would on a regular computer.

Once you learn file operations, you can apply them to a wide range of applications, such as logging data and creating configuration files.

It can also improve the completeness and debuggability of your products, so please give it a try.

I would be happy to help.

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