MicroPython and SCP: A Comprehensive Guide

MicroPython is a lean and efficient implementation of the Python 3 programming language that includes a small subset of the Python standard library and is optimized to run on microcontrollers and constrained systems. Secure Copy Protocol (SCP) is a network protocol used for securely transferring files between a local and a remote host or between two remote hosts. Combining MicroPython with SCP allows developers to transfer files to and from MicroPython - enabled devices in a secure manner. This is especially useful when updating code on the device, transferring configuration files, or retrieving data logged by the device. In this blog post, we will explore the fundamental concepts of using SCP with MicroPython, how to use it, common practices, and best practices.

Table of Contents#

  1. Fundamental Concepts
  2. Usage Methods
  3. Common Practices
  4. Best Practices
  5. Conclusion
  6. References

Fundamental Concepts#

MicroPython#

MicroPython is designed to bring Python's high - level programming concepts to microcontrollers and embedded systems. It allows developers to write code in Python, which is then executed directly on the device, eliminating the need for cross - compilation in many cases.

Secure Copy Protocol (SCP)#

SCP is based on the Secure Shell (SSH) protocol. It uses SSH for authentication and encryption, ensuring that the data transferred between the source and destination is secure. SCP follows a simple client - server model, where the client initiates the file transfer request and the server responds accordingly.

Using SCP with MicroPython#

To use SCP with MicroPython, the device running MicroPython needs to have an SSH server implemented. Some MicroPython - enabled boards like the Pyboard with appropriate firmware can act as an SSH server. The client side can be a computer running an SCP client, such as the scp command in Linux or macOS, or a Python script using libraries like paramiko in Windows or other systems.

Usage Methods#

Using the scp Command (Client - side in Linux/macOS)#

Assume you have a MicroPython device with an SSH server running at IP address 192.168.1.100, and you want to transfer a file test.py from your local machine to the device.

scp test.py [email protected]:/flash

Here, root is the username, 192.168.1.100 is the IP address of the device, and /flash is the destination directory on the device.

Using paramiko in Python (Cross - platform)#

The following is a Python script that uses the paramiko library to transfer a file using SCP.

import paramiko
from scp import SCPClient
 
def createSSHClient(server, port, user, password):
    client = paramiko.SSHClient()
    client.load_system_host_keys()
    client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
    client.connect(server, port, user, password)
    return client
 
ssh = createSSHClient('192.168.1.100', 22, 'root', 'password')
scp = SCPClient(ssh.get_transport())
scp.put('test.py', '/flash')
scp.close()
ssh.close()

In this script, we first create an SSH client using paramiko, then use SCPClient from the scp library to transfer the file test.py to the /flash directory on the device.

Common Practices#

Transferring Code Updates#

One common use case is to transfer updated Python code to the MicroPython device. You can write your code on your local machine, test it in a simulated environment if possible, and then transfer it to the device using SCP.

scp main.py [email protected]:/flash

Retrieving Logs#

If your MicroPython device is logging data, you can use SCP to retrieve the log files.

scp [email protected]:/flash/log.txt .

Here, the log file log.txt is retrieved from the device and saved to the current directory on the local machine.

Best Practices#

Secure Authentication#

Use strong passwords or public - key authentication for SSH. Public - key authentication is more secure as it uses cryptographic keys instead of passwords. You can generate an SSH key pair on your local machine and copy the public key to the MicroPython device.

Error Handling#

When using SCP in Python scripts, add proper error handling. For example, in the paramiko script above, you can add try - except blocks to handle connection errors, authentication failures, etc.

import paramiko
from scp import SCPClient
 
def createSSHClient(server, port, user, password):
    client = paramiko.SSHClient()
    client.load_system_host_keys()
    client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
    try:
        client.connect(server, port, user, password)
        return client
    except paramiko.AuthenticationException:
        print("Authentication failed, please verify your credentials.")
    except paramiko.SSHException as sshException:
        print(f"Could not establish SSH connection: {sshException}")
    except Exception as e:
        print(f"Unexpected error: {e}")
    return None
 
ssh = createSSHClient('192.168.1.100', 22, 'root', 'password')
if ssh:
    scp = SCPClient(ssh.get_transport())
    try:
        scp.put('test.py', '/flash')
    except Exception as e:
        print(f"Error during file transfer: {e}")
    finally:
        scp.close()
        ssh.close()

Testing in a Safe Environment#

Before deploying code updates or making changes to the device's configuration files, test the SCP transfer and the new code in a safe, isolated environment. This can prevent issues such as device malfunctions or data loss.

Conclusion#

Using SCP with MicroPython provides a secure and convenient way to transfer files between a local machine and a MicroPython - enabled device. By understanding the fundamental concepts, usage methods, common practices, and best practices, developers can efficiently manage code updates, retrieve data, and configure their devices. Whether you are a hobbyist or a professional developer, these techniques can significantly enhance your MicroPython development workflow.

References#

2025-10