• download latest micropython esp8266 firmware for your board

• on your host system install python3

• install esptool, rshell, ampy on your host to communicate with esp32 board

  # Example on Linux 
  sudo pip3 install esptool
  sudo pip3 install rshell
  sudo pip3 install adafruit-ampy

• connect board via USB. Run command:

   dmesg | grep tty

  that will help to find ttyUSB connection port.This port will be used later for all communication operations

• check board flash status. (In this example and below we assume that port=ttyUSB0)

   esptool.py --port /dev/ttyUSB0 flash_id

• erase board flash before new firmware uploading

   esptool.py --chip esp32 --port /dev/ttyUSB0 erase_flash

• burn new firmware

   esptool.py --chip esp32 --port /dev/ttyUSB0 write_flash -z 0x1000 [your esp32 firmware .bin]

• For board CLI access rshell can be used:

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

  after board prompt appears ">" you will have access to some board commands:

  args      cat       connect   echo      exit      filetype  ls        repl      rsync
  boards    cd        cp        edit      filesize  help      mkdir     rm        shell 
  

• repl command will start micropython interactive shell.

  Also this shell can be used for board soft reboots(Ctrl+D).

  Hard reboots can be done by board "RST" button.

• ampy utility can be used for storing/deleting files, directories creation/removing and scripts run

  export AMPY_PORT=/dev/ttyUSB0
  ampy mkdir /lib
  ampy put blynklib_mp.py /lib/blynklib_mp.py
  ampy put test.py test.py
  ampy run test.py

The firmware including the MicroPython subsystem is stored in the onboard flash. The remaining capacity is available for use. For reasons connected with the physical architecture of the flash memory part of this capacity may be inaccessible as a filesystem. In such cases this space may be employed by incorporating user modules into a firmware build which is then flashed to the device.

There are two ways to achieve this:

• frozen modules
• frozen bytecode.

Frozen modules store the Python source with the firmware.

For custom esp8266 firmware build creation:

• install docker to your host system. Steps how to do it under different OS described here

• clone with git esp8266 docker repository. Virtual environment will be needed for firmware build operation.

  git clone https://github.com/enqack/docker-esp8266-micropython.git
  cd ./docker-esp8266-micropython

• place your library module to docker-esp8266-micropython root

• modify Dockerfile. You need place your library module to esp8266 frozen modules directory. Thus Copy instruction in Dockerfile should be placed after 'RUN apt-get update' and before 'USER micropython'

  RUN apt-get update ...
  ...    
  COPY blynklib_mp.py /micropython/ports/esp8266/modules/blynklib_mp.py
  USER micropython
  ...
  

• follow this instructions to build and copy custom esp8266 firmware.

  Build process can take some time ~ 15-40 minutes.

• after firmware created and copied locally - you can try to burn it with esptool to your ESP8266 board.

• connect to board CLI with rshell and test blynklib_mp availability within repl

  import blynklib_mp
  print(blynklib_mp.LOGO)

Frozen bytecode approach uses the cross compiler to convert the source to bytecode which is then stored with the firmware.

Examine this document to get more details how to compile *.py files into *.mpy bytecode

After *.mpy files can be placed to /lib directory of esp8266 board with ampy tool. Libraries *.mpy can be simply imported in the same manner as standard *.py library

import blynklib_mp

Note!! During custom firmware creation your libraries will be converted and adopted to esp8266 environment automatically. So you can create custom build and then just copy *.mpy files from docker system to local

docker cp micropython:/micropython/ports/esp8266/build/frozen_mpy/blynklib_mp.mpy blynklib_mp.mpy

Micropython allows to use core network module for WiFi connection setup.

In script just place:

import network

WIFI_SSID = 'YourWifiSSID'
WIFI_PASS = 'YourWifiPassword'

wifi = network.WLAN(network.STA_IF)
wifi.active(True)
wifi.connect(WIFI_SSID, WIFI_PASS)

# check if board connected 
connect_status = wifi.isconnected()