Getting started with MicroPython and ESP8266

Table of contents

  1. Introduction
  2. Flashing the SOC
  3. Install better tooling
    1. ampy
    2. rshell
      1. Moving files to flash
      2. Executing scripts
  4. Additional resources

Introduction

A while ago I bought some ESP8266 and ESP32 dev boards to play around with and I finally found a project to try it out.

For my project, I used ESP32 but I could easily choose ESP8266. This guide contains which tools I use and how I prepared my workspace to code for ESP8266.

ESP8266 and ESP32 boards

This guide covers:

  • flashing SOC
  • install proper tooling
  • deploying a simple script

Make sure that you are using a good USB cable. I had some problems with mine and once I replaced it everything started to work.

Flashing the SOC

Plug your ESP8266 to USB port and check if the device was recognized with executing dmesg | grep ch341-uart.

Then check if the device is available under /dev/ by running ls /dev/ttyUSB*.

Linux users: if a device is not available be sure you are in dialout group. You can check this by executing groups $USER. You can add a user to dialout group with sudo adduser $USER dialout.

After these conditions are meet go to the navigate to https://micropython.org/download/esp8266/ and download esp8266-20200902-v1.13.bin.

mkdir esp8266-test
cd esp8266-test

wget https://micropython.org/resources/firmware/esp8266-20200902-v1.13.bin

After obtaining firmware we will need some tooling to flash the firmware to the board.

sudo pip3 install esptool

You can read more about esptool at https://github.com/espressif/esptool/.

Before flashing the firmware we need to erase the flash on device. Substitute USB0 with the device listed in output of ls /dev/ttyUSB*.

esptool.py --port /dev/ttyUSB0 erase_flash

If flash was successfully erased it is now time to flash the new firmware to it.

esptool.py --port /dev/ttyUSB0 --baud 460800 write_flash --flash_size=detect 0 esp8266-20200902-v1.13.bin

If everything went ok you can try accessing MicroPython REPL with screen /dev/ttyUSB0 115200 or picocom /dev/ttyUSB0 -b115200.

Sometimes you will need to press ENTER in screen or picocom to access REPL.

When you are in REPL you can test if all is working properly following steps.

> import machine
> machine.freq()

This should output a number representing a frequency of the CPU (mine was 80000000).

When you are in screen or picocom these can help you a bit.

Key Command
CTRL+d preforms soft reboot
CTRL+a x exits picocom
CTRL+a \ exits screen

Install better tooling

Now, to make our lives a little bit easier there are couple of additional tools that will make this whole experience a little more bearable.

There are twq cool ways of uploading local files to SOC flash.

ampy

# installing ampy
sudo pip3 install adafruit-ampy

Listed below are some common commands I used.


# uploads file to flash
ampy --delay 2 --port /dev/ttyUSB0 put boot.py

# lists file on flash
ampy --delay 2 --port /dev/ttyUSB0 ls

# outputs contents of file on flash
ampy --delay 2 --port /dev/ttyUSB0 cat boot.py

I added delay of 2 seconds because I had problems with executing commands.

rshell

Even though ampy is a cool tool I opted with rshell in the end since it's much more polished and feature rich.

# installing ampy
sudo pip3 install rshell

Now that rshell is installed we can connect to the board.

rshell --buffer-size=30 -p /dev/ttyUSB0 -a

This will open a shell inside bash and from here you can execute multiple commands. You can check what is supported with help once you are inside of a shell.

m@turing ~/Junk/esp8266-test
$ rshell --buffer-size=30 -p /dev/ttyUSB0 -a

Using buffer-size of 30
Connecting to /dev/ttyUSB0 (buffer-size 30)...
Trying to connect to REPL  connected
Testing if ubinascii.unhexlify exists ... Y
Retrieving root directories ... /boot.py/
Setting time ... Sep 06, 2020 23:54:28
Evaluating board_name ... pyboard
Retrieving time epoch ... Jan 01, 2000
Welcome to rshell. Use Control-D (or the exit command) to exit rshell.
/home/m/Junk/esp8266-test> help

Documented commands (type help <topic>):
========================================
args    cat  connect  date  edit  filesize  help  mkdir  rm     shell
boards  cd   cp       echo  exit  filetype  ls    repl   rsync

Use Control-D (or the exit command) to exit rshell.

Inside a shell ls will display list of files on your machine. To get list of files on flash folder /pyboard is remapped inside the shell. To list files on flash you must perform ls /pyboard.

Moving files to flash

To avoid copying files all the time I used rsync function from the inside of rshell.

rsync . /pyboard

Executing scripts

It is a pain to continuously reboot the device to trigger /pyboard/boot.py and there is a better way of testing local scripts on remote device.

Lets assume we have src/freq.py file that displays CPU frequency of a remote device.

# src/freq.py

import machine
print(machine.freq())

Now lets upload this and execute it.

# syncs files to remove device
rsync ./src /pyboard

# goes into REPL
repl

# we import file by importing it without .py extension and this will run the script
> import freq

# CTRL+x will exit REPL

Additional resources


Comment, contact: The easiest way to contact me is by writing me a message on Telegram (https://t.me/mitjafelicijan).

You can also just write me an email at m@mitjafelicijan.com.



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