Wemos MicroPython


#MicroPython: Getting started!

Another quick tutorial, this time for MicroPython on ESP32. 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 post. I included some links at the end of each topic to extend the info. Feel free to visit them if you want more info, or write a comment I will try to respond it.

Python 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.

Fortunately, there is a port of MicroPython for the ESP32, and this time I've installed the firmware on the Wemos board. The development tool includes a ESP-WROOM-32 microcontroller.

More Info

Wemos development tool
MicroPython


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.

Installing esptools tool
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

Python 3.6
pip
esptool
ampy

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.

Connect the Wemos to the PC using an USB cable, 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.

Checking Device Manager
Fig. 2: Windows Device Manager.

First, open a cmd/terminal. The flash of the ESP32 need to be erased. To do so, just give the command bellow on the command line:

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

You need to change the COM17 or /dev/ttyUSB0 to the serial port where your ESP32 is connected.

After this, we can upload the firmare (.bin file) to the ESP32 with the command bellow.

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

Error by uploading MicroPython firmware
Fig. 3: Error by uploading MicroPython firmware

If everything goes right, you get some results as the one on Fig. 4.

Uploading MicroPython Firmware
Fig. 4: Uploading MicroPython Firmware

Programming using Atom and PyMark plugin

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

Install Packages on Atom.io
Fig. 5: Install Packages on Atom.io

Type pymark to search the plugin, wait a second, and then when it comes in the plugin list, install it using the install button (Fig. 6) -version 1.2.0 is available.

PyMark Installation
Fig. 6: pymark 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.

Atom Console
Fig. 7: Atom pymark 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 again 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.

 Global settings
Fig. 8: pymark Global settings

More Info

ESP32 Firmware
Atom.io
Pymark Plugin

Uploading files using adafruit-ampy

The MicroPython firmware for ESP32 doesn't have a FTP server as standard function as the version for the Wipy2.0. Then, 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>
wp2_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_, wp2_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.

More Info

ampy
ESP32-MicroPython

If you have further questions, please don't hesitate to comment this article.

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