Jupyter MicroPython extended Kernel

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Jupyter MicroPython extended Kernel

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Description

Tested with MicroPython v1.12 - v1.27 on ESP32-Boards in Jupyter Lab.

Typically used with MicroPython boards over the

• USB / Serial interface.

It also allows

• serial connection with the Uart-REPL, f.e. classic BlueTooth with HC-05/HC-06,
• connecting over WiFi with the Web-REPL and
• connecting over Bluetooth Low Energy with the BLE-REPL (based on bleak).

With the cell magic %%iPython you can run normal Python in MicroPython-Jupyter Notebooks.
Within such a Python cell functions and variables on the controller can be accessed with the special functions micropython_eval, micropython_value and micropython_run, meaning, for example, that data captured by the controller can be displayed directly with matplotlib.

For details see Example further down, the KernelTest.ipynb Notebook and the example Notebooks.

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Background

Why another MicroPython kernel for JuypterLab?

After using Julian Todd's excellent kernel for a while, I wanted to program an ESP32 via a BLE connection instead of USB. I simply couldn't establish a connection with Carlos Gil Gonzalez's great kernel. However, this kernel offers a very useful feature: calling IPython code in a MicroPython notebook and facilitating data exchange between MicroPython and IPython. Another kernel is Jos Verlinde's. It allows you to call MicroPython code in an IPython notebook using a Cell Magic. But I wanted the exact opposite: an IPython cell in a MicroPython notebook.

Therefore, I took Todd's kernel as a base, did a little refactoring and added the ideas from the other two kernels.
The BLE connection is implemented with the bleak library, which doesn't require administrator privileges for installation on Windows, which is important in environments with restricted rights, such as is common in many schools.

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Installation

Install JupyterLab

If not done yet, set up JupyterLab:

Linux:

python3 -m venv .venv
source .venv/bin/activate

or Windows:

python -m venv .venv
.venv\Scripts\activate

Then (Linux, Windows):

pip install --upgrade pip
pip install jupyterlab

Install JupyterLab MicroPython extended Kernel

Requirements

Linux & Macintosh:
On Linux and Macintosh systems a USB driver is generally already installed.
If you are on Linux and don't have the correct permissions to access the Serial ports you will get a "permissions error". Fix it by adding yourself to the dialout and tty groups:

sudo usermod -a -G tty your_user_name
sudo usermod -a -G dialout your_user_name

Windows:
On Windows systems, usually a USB driver needs to be installed:
in most cases, you will need the CP210x Universal Windows Driver from the Silicon Lab download site.
Extract this file and, on standard 64-bit Windows systems (almost all of them these days), run the file CP210xVCPInstaller_x64.exe.

Install dependencies:

pip install --upgrade unsync bleak pyserial websocket-client

Install the kernel:

pip install jupyter-micropython-extended-kernel

and register the kernel within JupyterLab so it can be selected for use in notebooks:

python -m jupyter_micropython_extended_kernel.install

See also Installing the kernel if in a running JupyterLab environment.

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Running

Start JupyterLab:

Linux:

jupyter lab --notebook-dir ~

Windows:

jupyter lab --notebook-dir %USERPROFILE%

In the launcher click on the MicroPython - extended - USB button to create a new NoteBook or, if a NoteBook is already loaded, select the MicroPython - Extended - USB-kernel in the upper right corner.

If not already running on your ESP32 or ESP8266, you have to flash MicroPython to your ESP32 or ESP8266. Please look at micropython.org/download for how to do it, or f.e. here.

Connect controller:

Now connect the ESP32 or ESP8266 using a USB cable, write the following command into the first cell and run it:

%serialconnect

If everything goes well, you see something like

[...]
Connecting to --port=/dev/ttyUSB0 --baud=115200  
 ** Connected to SerialPort: port=/dev/ttyUSB0 baudrate=115200 **
Ready.

This differs from system to system and what you have done before, but Ready. should appear at the end.

Program!

Now execute in a cell:

print( "Hello world!" )

This gives:

Hello world!

as output.

For more examples please go to the KernelTest.ipynb notebook.

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Example:

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MicroPython cell:

import random

def getRandom( bits, offset=2**7, factor=1 ):
    return ( random.getrandbits(bits)-offset ) * factor

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Python-3 cells:

Calling function getRandom on controller with default parameters and print return value on local PC:

%%iPython
# Test call with default parameters:
iRandom = micropython_run( "getRandom", 8 )
print( f"iRandom = {iRandom}" )

Call micropython_run( 'getRandom', bits=1, offset=0.5, factor=2 ) in a loop and display data in a dynamically updated plot:

%%iPython
# load libraries to display the plots
import bqplot.pyplot as plt
import numpy as np
from time import sleep

plt.clear()  # clear any previous plots
plt.show()

aData   = []
dataSum = 0

for i in range(100):
    dataSum += micropython_run( "getRandom", bits=1, offset=0.5, factor=2 )
    aData.append(dataSum)
    plt.plot(aData)
    sleep(0.1)

Output:

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Further notes

• Normally, you have to run %serialconnect every time you switch to a different notebook. Sometimes, disconnecting the device from the USB cable, reconnecting it, and then running %serialconnect helps.
• Endless loops can be stopped with "Esc ii", "Ctrl C" (does not work in some cases) or hitting the stop button at the top of the Notebook
  Also Kernel → Interrupt in the menu may help.
• To find out where your kernelspecs are stored, you can open a terminal with File→New→Terminal an then execute there jupyter kernelspec list.
• Restarting the kernel does not actually reboot the device!
• You can list all the magics with: %lsmagic