#Tutorial: Getting started with MicroPython

Another quick tutorial, this time for MicroPython on ESP32/ESP8266. You can find all the information that I'm writing in this post in different articles on the Internet but I've not found anything that summarizes all the topics. That is why I am writting this article. I included some links at the end of each topic to extend the info. Feel free to visit them, if you want more information, or write a comment I will try to reply it ASAP!

	Code: https://github.com/lemariva/ESP32-MicroPython

MicroPython & Board

What's MicroPython?

Quoting the official micropython page results in the following

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 optimised to run on microcontrollers and in constrained environments.

As you see, in my last posts (sorry about the link, I need some pagekit taxonomy!), I have been programming the Wipy 2.0. This board is a tiny MicroPython enabled WiFi & Bluetooth IoT development platform.

Other development boards/kits, that support MicroPython are the following:

The cheapest boards are the ESP8266. They only have 160kb RAM, which can be a problem and you usually get a memory error exception, when you import 3 or 4 libraries. The ESP32 WROOM has 512kb RAM and the WROVER 4MB. There is also a new WROVER-B that has 8MB RAM.

More Info

Software Requirements

You can download and compile the MicroPython firmware from the GitHub repository, or you can download a compiled firmware from here. I took the second way.

To download the firmware to the ESP32 microcontroller, you have to install Python. You can use either Python 2.7 or Python 3.6. Then, you need to install pip. A tutorial for installing pip on Windows can be found here. pip can be downloaded from get-pip. After that, you need to install the esptools using the following command

pip install esptool
# or usually on windows
python -m pip install esptool 

You should get something like the Fig 1 (I typed python3 because I've the two versions (2.7 & 3.6) on Windows, so I changed the name of the executable file to python3.exe). Remember to include the Python directory to the Windows path in the Environment Variables.

Fig. 1: Installing esptool on Windows.

You should also install ampy. This tool is useful for uploading files to the ESP32 via serial interface. To do that, you need to type the following on a command prompt

python3 -m pip install adafruit-ampy

More Info

Firmware Download & Installation

Download the MicroPython firmware from here. You have to download the image under Firmware for ESP32 boards. Do not try another firmware; it is not going to work. If you have a version with extra pSRAM (WROVER-A/B modules) flash the version with SPIRAM. If you need to use the BLE module, read this tutorial: Tutorial: MicroPython and Bluetooth (BLE)

Connect the Wemos to a USB port on your PC, and check the serial interface number where the CP201x is connected (turn the board on, if it is not). On Windows, open the Device Manager and look under Ports (COM & LPT). In my case, the port is COM17. On Linux, it should be under /dev/ttyUSBx (change x to the corresponding port number). Using dmesg you should look for something like this: usb 5-3: cp210x converter now attached to ttyUSB0.

Fig. 2: Windows Device Manager.

First, open a cmd/terminal. You need first to erase the flash of the ESP32. To do so, just type the following comand lines:

# on Windows
python -m esptool --port COM17 erase_flash 
# on Linux
python -m esptool --port /dev/ttyUSB0 erase_flash 

Change the COM17 or /dev/ttyUSB0 to the serial port, where your ESP32 is connected.

After doing this, you can flash the firmware (.bin file) to the ESP32 typing these lines:

# for Windows
python -m esptool --port COM17 --baud 460800 write_flash --flash_mode dio --flash_size=detect 0x1000 <firmware_name>.bin
# for Linux
python -m esptool --port /dev/ttyUSB0 --baud 460800 write_flash --flash_mode dio --flash_size=detect 0x1000 <firmware_name>.bin

Again, replace the port with the ESP32 COM/Serial port, and change the <firmware_name>.bin with the path/file, where your firmware is located. If you get an error like Fig. 3, you should close all open connections to the board (e.g. putty, serial console etc.).

Fig. 3: Error by uploading MicroPython firmware

If everything goes right, you'll get something like Fig. 4.

Fig. 4: Uploading MicroPython Firmware

Programming using Atom and PyMakr plugin

Download Atom.io and install it. Then, search for the plugin pymakr. To do so, go to Packages, then Settings View, and finally Install Packages/Themes (see Fig. 5).

Fig. 5: Install Packages on Atom.io

Type pymakr to search the plugin, wait, and install it using the install button (Fig. 6) version 1.2.0 is available.

Fig. 6: pymakr Installation

If everything goes right, you get a console on Atom (lower side of the right panel), that can be configured to connect to the ESP32. The console should look like Fig. 7.

Fig. 7: Atom pymakr Console

It is usually closed at the beginning; you need to click on the open button on the right. Before that, you should click on Settings to configure the port on which the Wemos board is connected. You can set a Global settings (Fig. 8) for all your projects or a Project settings, if you have more than one board connected to your PC and different projects running on these boards.

• Note for Windows users: COMXX should be written in uppercase, otherwise pymakr doesn't find the port and asks the DNS server to translate that address, which usually does not exist, and you get an error!

Fig. 8: pymakr Global settings

Pymakr size problem - Atom 1.30:

If your console size is too small and you cannot resize it like this one:

Fig. 9: pymakr Console too small and not resizable

you need to disable the atom-ide-ui package (Packages > Settings View > Manage Packages):

Fig. 10: atom-ide-ui Package

It is a known bug.

More Info

Uploading files using adafruit-ampy

The MicroPython firmware for ESP32 doesn't have a FTP server like the version for PyCOM boards. You have to upload the files using the serial interface. The sync button of the pymark plugin on Atom doesn't work with this firmware (with the Wipy 2.0, it works).

Write the following code in a file called boot.py changing the <ssid> and <wpa2_pass values to the right ones of your WiFi configuration

# boot.py

ssid_ = <ssid>
wpa2_pass = <wpa2_pass>

def do_connect():
    import network
    sta_if = network.WLAN(network.STA_IF)
    if not sta_if.isconnected():
        print('connecting to network...')
        sta_if.active(True)
        sta_if.connect(ssid_, wpa2_pass)
        while not sta_if.isconnected():
            pass
    print('network config:', sta_if.ifconfig())

do_connect()

You can upload the boot.py file to the Wemos board using ampy with the following command line

# for Windows
ampy --port COM17 put /pathToFile/boot.py
# for Linux
ampy --port /dev/ttyUSB0 put /pathToFile/boot.py

You can upload a simple FTP server to upload files using e.g. Filezilla. You will find the FTP Python file on my GitHub repository, together with a boot.py to connect to the WIFI Router.

Uploading files using PyMakr console in Atom

With the PyMakr plugin version newer than 1.30, it is possible to upload files not only to the WiPy2.0/3.0 but also to the ESP32/ESP8266 modules. You need to open your project, configure the Settings as described above and click on the Upload button (see Fig. 11). The files are uploaded and after that the board is rebooted.

If you have a main.py file with a while True: and you want to stop it, you can press CTRL+C after clicking inside the console. The while will be breaked and you can type your commands inside the console. This could be helpfull when the microcontroller is doing too many task, and the Upload file action fails. Additionally, you can switch the "safe_boot_on_upload": true, inside the pymakr.conf file.

Fig. 11: atom-ide-ui Package

More Info

If you have further questions, please don't hesitate to comment this article. But, first check the section: MicroPython! There are many interesting articles and projects to follow!