Blinking LEDs with Python: How to Code in Micro Python on the ESP8266/NodeMCU

Before when I talked about Circuit and Micro Python we have been looking at Adafruit and similar devices. Most of us, though, use the cheapest boards we can find, such as the Aliexpress NodeMCU and Wemos boards.

I did actually start with Micro Python using the official board from the Kickstarter, interestingly enough, but I quickly found I almost always needed internet connectivity, so have used wifi enabled boards for a lot of my projects since.

Don't worry, the cheap ESP8266 boards can play too!

While there are still a lot more libraries available for the ESP8266 in Arduino IDE land, I love the interactive and rapid development of Python, so I am willing to miss out on a few drivers.

Again, if you want the full Python, you are going to need Raspberry Pi and Python 3.6 >, but few of us would be happy leaving a full Raspberry Pi in a project long term, and these boards have lower power consumption.

Download the Firmware and ESP tool

Get the ESP8266 firmware from MicroPython.org and using PIP, grab the ESP tool

sudo pip install esptool

Now plug in your board and use the ESP tool to overwrite the firmware (rename the .bin file to firmware.bin)

esptool.py --port /dev/ttyUSB0 --baud 460800 write_flash --flash_size=detect 0 firmware.bin

First test

To check this worked, reset the board and use a serial terminal, such as Screen, to check the connection:

screen /dev/ttyUSB0 115200

You should see a prompt like this (maybe after some enter key presses)

>>>

Enter the following and hit return:
print("Woot!")

You should see Woot! as the response :)

The following can check the integrity of the firmware:

import esp
esp.check_fw()

Developing in Micro Python

Unlike the fancy Circuit Python Express, these boards don't have a drag and drop interface, but they do have nice third-party tools!

If you are using ESP8266/NodeMCU like me, install mpfshell
sudo pip install mpfshell

Otherwise, Adafruit created Ampy:
sudo pip3 install adafruit-ampy

Once you have run mpfshell, enter the following command to connect to your board:

open ttyUSB0

Now you can list, upload, download, create folders ... like a full shell.

You also have an interactive REPL.

Get the full command list here

Blink!

Now let's do the simple "hello world" equivalent of the firmware world!

Grab the code

Different boards have different LEDs and pins, so this will either/and light blue or red, or you might need to set the pin to a different number:

from time import sleep
import machine
from machine import Pin

redled = machine.Pin(0, machine.Pin.OUT)
blueled = machine.Pin(2, machine.Pin.OUT)

redled.value(0)
blueled.value(1)


for i in range(0,10):
    print(i)
    redled.value(1)
    blueled.value(0)
    sleep(1)
    redled.value(0)
    blueled.value(1)
    sleep(1)

To get the file onto your board use:

put blink.py

Now to run it, enter
repl

and now execute the script!
exec(open("blink.py").read())

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