MicroPython

boards Pycom

Description

Note: MicroPython on LoPy4 board is not actively supported by IoT-LAB.

MicroPython is an implementation of the Python programming language designed for highly constrained hardware platforms such as microcontrollers.

You can find a lot of documentation on the MicroPython website. The source code of MicroPython is hosted on GitHub.

Basic usage with IoT-LAB

In IoT-LAB, the ESP32 LoPy4 boards can run MicroPython firmware.

Once you run and flash MicroPython firmware, start using MicroPython the Pycom via the remote serial port of the board. The MicroPython REPL can be accessed as usual via the serial redirection mechanism (just press Enter once to get the REPL >>> prompt):

from the SSH frontend:

<login>@saclay:~$ nc lopy4-<id> 20000

>>>

from your local computer using an SSH tunnel:
```
$ ssh -L 20000:lopy4-<id>:20000 <login>@strasbourg.iot-lab.info
```
Then, in another terminal, connect to localhost:20000 with nc:
```
$ nc localhost 2000

>>>
```

Recommended local usage

Using nc is quite limited though: it’s not easily possible to use the Ctrl+D, Ctrl+E, etc keyboard shortcuts of the MicroPython REPL because they are first interpreted by the Linux shell.

That’s why it’s recommended to only interact with the REPL via an SSH tunnel and using local tools instead:

socat to redirect the TCP:20000 port in a TTY like file locally
miniterm.py from the pyserial Python package because it correctly forwards Ctrl+D, Ctrl+E, etc shortcuts to the REPL
the pymakr extension of VSCode

Setup the local REPL redirection

Open the SSH tunnel:

$ ssh -L 20000:lopy4-<id>:20000 <login>@strasbourg.iot-lab.info

Start the socat TCP to file redirection:

$ socat PTY,link=/tmp/ttyS0,echo=0,crnl TCP:localhost:20000

This command redirects the stream from localhost:20000 (which itself is connected to the serial port via the SSH tunnel) to the local pseudo-terminal in /tmp/ttyS0.

This way, /tmp/ttyS0 acts a local TTY, exactly like the board was plugged directly on the computer.

Access the REPL with miniterm

From this point, you can use miniterm.py to connect to the REPL:

miniterm.py /tmp/ttyS0 115200
--- Miniterm on /tmp/ttyS0  115200,8,N,1 ---
--- Quit: Ctrl+] | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H ---

>>>

Use the Ctrl+D to reset the board, Ctrl+E to switch to paste mode.

Access the REPL with `pymakr`

This pycom documentation page explains how to install the pymakr extension of the VSCode editor.

Edit the Pymakr global settings and change/add the address field as follows:

    "address": "/tmp/ttyS0"

Then use the control in the bottom menu of VSCode to Run/Upload/Download MicroPython scripts.