DESK-MX6UL-AN-0004: Using Python for Embedded applications
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 This application note has been validated using the kit version in the History table. |
Contents
History[edit | edit source]
| Version | Date | Development Kit version |
|---|---|---|
| Oct 2021 | ||
| 2.0.0 | --- 2022 | DESK-MX6UL-L 3.0.0 |
Introduction[edit | edit source]
As found on Python official website, Python is a programming language that lets you work more quickly and integrate your systems more effectively and also Python can be easy to pick up whether you're a first-time programmer or you're experienced with other languages.
These sentences got a real confirmation if you have a look at the IEEE Top Programming Languages 2021 ranking. As you can see in the following picture Python reached the Top of the ranking even more than the native C language used since the beginning in Embedded systems programming:
As reported in this article The C/C++ programming languages dominate embedded systems programming, though they have a number of disadvantages. Python, on the other hand, has many strengths that make it a great language for embedded systems.
This application note provides some examples of software packages installation that can be used for building an Industrial IoT Gateway adding python3 libraries to the SBC Lynx platform.
Python on DESK[edit | edit source]
python3 application is already present on DESK-MX6UL-L dave-image-devel root file system.
Installing python packages[edit | edit source]
First of all check for the default installed python/pip version in the DESK-MX6UL root file system:
root@desk-mx6ul-lynx:~# python3 --version Python 3.9.4 root@desk-mx6ul-lynx:~#
pip3 is not present - by default - on standard root file system, but can be easily installed using python:
root@desk-mx6ul-lynx:~# curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0:00:01 --:--:-- 1846k
root@desk-mx6ul-lynx:~# python3 get-pip.py
Collecting pip
Downloading pip-21.3.1-py3-none-any.whl (1.7 MB)
|################| 1.7 MB 2.1 MB/s
Collecting setuptools
Downloading setuptools-60.5.0-py3-none-any.whl (958 kB)
|###########| 958 kB 2.1 MB/s
Collecting wheel
Downloading wheel-0.37.1-py2.py3-none-any.whl (35 kB)
Installing collected packages: wheel, setuptools, pip
Successfully installed pip-21.3.1 setuptools-60.5.0 wheel-0.37.1
WARNING: Running pip as the 'root' user can result in broken permissions and conflicting behaviour with the system package manager. It is recommended to use a virtual environment instead: https://pip.pypa.io/warnings/venv
root@desk-mx6ul-lynx:~#
After the installation, pip3 is the latest version available for Python3 3.9.4:
root@desk-mx6ul-lynx:~# pip3 --version pip 21.3.1 from /usr/lib/python3.9/site-packages/pip (python 3.9) root@desk-mx6ul-lynx:~#
Virtual environments[edit | edit source]
As explained on python3 12. Virtual Environments and Packages tutorial it is better to "create a virtual environment, a self-contained directory tree that contains a Python installation for a particular version of Python, plus a number of additional packages"
This avoids the problem related to Applications that sometimes need a specific version of a library.
- for example, create the
virtual environmentnamed desk
root@desk-mx6ul-lynx:~# python3 -m venv desk-env root@desk-mx6ul-lynx:~# which pip3 /usr/bin/pip3 root@desk-mx6ul-lynx:~#
- activate the
virtual environment
root@desk-mx6ul-lynx:~# source desk-env/bin/activate (desk-env) root@desk-mx6ul-lynx:~# which pip3 /home/root/desk-env/bin/pip3 (desk-env) root@desk-mx6ul-lynx:~#
- update pip3 in the the
virtual environment
(desk-env) root@desk-mx6ul-lynx:~# /home/root/desk-env/bin/python3 -m pip install --upgrade pip
Collecting pip
Using cached pip-21.3.1-py3-none-any.whl (1.7 MB)
Installing collected packages: pip
Attempting uninstall: pip
Found existing installation: pip 20.2.3
Uninstalling pip-20.2.3:
Successfully uninstalled pip-20.2.3
Successfully installed pip-21.3.1
(desk-env) root@desk-mx6ul-lynx:~# /home/root/desk-env/bin/pip3 --version
pip 21.3.1 from /home/root/desk-env/lib/python3.9/site-packages/pip (python 3.9)
(desk-env) root@desk-mx6ul-lynx:~#
In this way it is possible to install the required packages (with their specific version required) only in this virtual environment (which may differ from the root installation).
pip package installation[edit | edit source]
For the purposes of this Application Note, pip3 has been used to install some python packages typically used in an Industrial Gateway equipment
In this example, the following packages are installed pyserial and pymodbus (for bus communications), flask, fastapi (web framework), bottle (lightweight WSGI micro web-framework), requests (HTTP library), schema, ssdp, scapy (network packet manipulation), nmap, ujson (JSON framework):
(desk-env) root@desk-mx6ul-lynx:~# pip3 install pyserial
Collecting pyserial
Downloading pyserial-3.5-py2.py3-none-any.whl (90 kB)
|################################| 90 kB 780 kB/s
Installing collected packages: pyserial
WARNING: Value for scheme.platlib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Value for scheme.purelib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Additional context:
user = False
home = None
root = None
prefix = None
Successfully installed pyserial-3.5
(desk-env) root@desk-mx6ul-lynx:~# pip3 install modbus
Collecting pymodbus
Downloading pymodbus-2.5.3-py2.py3-none-any.whl (154 kB)
|#############################| 154 kB 1.5 MB/s
Collecting six>=1.15.0
Downloading six-1.16.0-py2.py3-none-any.whl (11 kB)
Requirement already satisfied: pyserial>=3.4 in ./desk-env/lib/python3.9/site-packages (from pymodbus) (3.5)
Installing collected packages: six, pymodbus
WARNING: Value for scheme.platlib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Value for scheme.purelib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Additional context:
user = False
home = None
root = None
prefix = None
Successfully installed pymodbus-2.5.3 six-1.16.0
(desk-env) root@desk-mx6ul-lynx:~# pip3 install fastapi
Collecting fastapi
Downloading fastapi-0.72.0-py3-none-any.whl (52 kB)
|################################| 52 kB 68 kB/s
Collecting starlette==0.17.1
Downloading starlette-0.17.1-py3-none-any.whl (58 kB)
|###############################| 58 kB 594 kB/s
Collecting pydantic!=1.7,!=1.7.1,!=1.7.2,!=1.7.3,!=1.8,!=1.8.1,<2.0.0,>=1.6.2
Downloading pydantic-1.9.0-py3-none-any.whl (140 kB)
|############################| 140 kB 2.3 MB/s
Collecting anyio<4,>=3.0.0
Downloading anyio-3.5.0-py3-none-any.whl (79 kB)
|###############################| 79 kB 729 kB/s
Collecting typing-extensions>=3.7.4.3
Downloading typing_extensions-4.0.1-py3-none-any.whl (22 kB)
Collecting sniffio>=1.1
Downloading sniffio-1.2.0-py3-none-any.whl (10 kB)
Collecting idna>=2.8
Downloading idna-3.3-py3-none-any.whl (61 kB)
|###############################| 61 kB 805 kB/s
Installing collected packages: sniffio, idna, typing-extensions, anyio, starlette, pydantic, fastapi
WARNING: Value for scheme.platlib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Value for scheme.purelib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Additional context:
user = False
home = None
root = None
prefix = None
Successfully installed anyio-3.5.0 fastapi-0.72.0 idna-3.3 pydantic-1.9.0 sniffio-1.2.0 starlette-0.17.1 typing-extensions-4.0.1
(desk-env) root@desk-mx6ul-lynx:~# pip3 install bottle
Collecting bottle
Downloading bottle-0.12.19-py3-none-any.whl (89 kB)
|################################| 89 kB 688 kB/s
Installing collected packages: bottle
WARNING: Value for scheme.platlib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Value for scheme.purelib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Additional context:
user = False
home = None
root = None
prefix = None
Successfully installed bottle-0.12.19
(desk-env) root@desk-mx6ul-lynx:~# pip3 install requests
Collecting requests
Downloading requests-2.27.1-py2.py3-none-any.whl (63 kB)
|##############################| 63 kB 124 kB/s
Collecting charset-normalizer~=2.0.0
Downloading charset_normalizer-2.0.10-py3-none-any.whl (39 kB)
Requirement already satisfied: idna<4,>=2.5 in ./desk-env/lib/python3.9/site-packages (from requests) (3.3)
Collecting urllib3<1.27,>=1.21.1
Downloading urllib3-1.26.8-py2.py3-none-any.whl (138 kB)
|##############################| 138 kB 632 kB/s
Collecting certifi>=2017.4.17
Downloading certifi-2021.10.8-py2.py3-none-any.whl (149 kB)
|###########################| 149 kB 547 kB/s
Installing collected packages: urllib3, charset-normalizer, certifi, requests
WARNING: Value for scheme.platlib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Value for scheme.purelib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Additional context:
user = False
home = None
root = None
prefix = None
Successfully installed certifi-2021.10.8 charset-normalizer-2.0.10 requests-2.27.1 urllib3-1.26.8
(desk-env) root@desk-mx6ul-lynx:~# pip3 install schema
Collecting schema
Downloading schema-0.7.5-py2.py3-none-any.whl (17 kB)
Collecting contextlib2>=0.5.5
Downloading contextlib2-21.6.0-py2.py3-none-any.whl (13 kB)
Installing collected packages: contextlib2, schema
WARNING: Value for scheme.platlib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Value for scheme.purelib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Additional context:
user = False
home = None
root = None
prefix = None
Successfully installed contextlib2-21.6.0 schema-0.7.5
(desk-env) root@desk-mx6ul-lynx:~# pip3 install ssdp
Collecting ssdp
Downloading ssdp-1.1.0-py2.py3-none-any.whl (4.3 kB)
Installing collected packages: ssdp
WARNING: Value for scheme.platlib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Value for scheme.purelib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Additional context:
user = False
home = None
root = None
prefix = None
Successfully installed ssdp-1.1.0
(desk-env) root@desk-mx6ul-lynx:~# pip3 install scapy
Collecting scapy
Downloading scapy-2.4.5.tar.gz (1.1 MB)
|#########| 1.1 MB 1.3 MB/s
Preparing metadata (setup.py) ... - \ done
Using legacy 'setup.py install' for scapy, since package 'wheel' is not installed.
Installing collected packages: scapy
WARNING: Value for scheme.platlib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Value for scheme.purelib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Additional context:
user = False
home = None
root = None
prefix = None
Running setup.py install for scapy ... / - \ | / done
Successfully installed scapy-2.4.5
(desk-env) root@desk-mx6ul-lynx:~# pip3 install nmap
Collecting nmap
Downloading nmap-0.0.1-py3-none-any.whl (2.7 kB)
Installing collected packages: nmap
WARNING: Value for scheme.platlib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Value for scheme.purelib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Additional context:
user = False
home = None
root = None
prefix = None
Successfully installed nmap-0.0.1
(desk-env) root@desk-mx6ul-lynx:~# pip3 install ujson
Collecting ujson
Downloading ujson-5.1.0.tar.gz (7.1 MB)
|###############| 7.1 MB 10 kB/s
WARNING: Value for prefixed-purelib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /tmp/pip-build-env-aajn4vfi/normal/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Value for prefixed-platlib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /tmp/pip-build-env-aajn4vfi/normal/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Additional context:
user = False
home = None
root = None
prefix = '/tmp/pip-build-env-aajn4vfi/normal'
WARNING: Value for prefixed-purelib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /tmp/pip-build-env-aajn4vfi/overlay/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Value for prefixed-platlib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /tmp/pip-build-env-aajn4vfi/overlay/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Additional context:
user = False
home = None
root = None
prefix = '/tmp/pip-build-env-aajn4vfi/overlay'
WARNING: Value for purelib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Additional context:
user = False
home = None
root = None
prefix = None
WARNING: Value for platlib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
Installing build dependencies ... - \ | / - \ | / - done
Getting requirements to build wheel ... done
Preparing metadata (pyproject.toml) ... - \ done
Building wheels for collected packages: ujson
Building wheel for ujson (pyproject.toml) ... - \ | / - \ | done
Created wheel for ujson: filename=ujson-5.1.0-cp39-cp39-linux_armv7l.whl size=37764 sha256=10ac0ac0859d098528a5985fb09ddc0dcb2e7682ff9d587cbae8be01dafe3edd
Stored in directory: /home/root/.cache/pip/wheels/5b/11/cb/2e1acde83fd78adc6581984c55442e63d7595711b0b62d8110
Successfully built ujson
Installing collected packages: ujson
WARNING: Value for scheme.platlib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Value for scheme.purelib does not match. Please report this to <https://github.com/pypa/pip/issues/10151>
distutils: /home/root/desk-env/lib/python3.9/site-packages
sysconfig: /usr/lib/python3.9/site-packages
WARNING: Additional context:
user = False
home = None
root = None
prefix = None
Successfully installed ujson-5.1.0
(desk-env) root@desk-mx6ul-lynx:~#
check for installed packages and version[edit | edit source]
(desk-env) root@desk-mx6ul-lynx:~# pip3 list Package Version ------------------ --------- anyio 3.5.0 bottle 0.12.19 certifi 2021.10.8 charset-normalizer 2.0.10 click 8.0.3 contextlib2 21.6.0 fastapi 0.72.0 Flask 2.0.2 idna 3.3 itsdangerous 2.0.1 Jinja2 3.0.3 MarkupSafe 2.0.1 nmap 0.0.1 pip 21.3.1 pydantic 1.9.0 pymodbus 2.5.3 pyserial 3.5 requests 2.27.1 scapy 2.4.5 schema 0.7.5 setuptools 49.2.1 six 1.16.0 sniffio 1.2.0 ssdp 1.1.0 starlette 0.17.1 typing_extensions 4.0.1 ujson 5.1.0 urllib3 1.26.8 Werkzeug 2.0.2 wheel 0.37.1 (desk-env) root@desk-mx6ul-lynx:~#
import packages[edit | edit source]
Finally, after the installation steps, it is possible to import the packages:
(desk-env) root@desk-mx6ul-lynx:~# python3 Python 3.9.4 (default, Apr 4 2021, 18:23:51) [GCC 10.2.0] on linux Type "help", "copyright", "credits" or "license" for more information. >>> import sys >>> import os >>> import time >>> import ssl >>> import nmap >>> import scapy >>> import serial >>> import pymodbus >>> import schema >>> import ssdp >>> import requests >>> import flask >>> import bottle >>> import ujson >>> import fastapi >>> (desk-env) root@desk-mx6ul-lynx:~#
