ESP32 Micropython

Board preparation

• download latest micropython 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]

Board CLI

• 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.

Board files/directories operations

• 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

Micropython libraries compiltation

Micropython provides ability to compile source code into .mpy frozen module file. Main advantage of this that .mpy files will consume less RAM compared to raw Python .py source files

For .mpy file compilation you need:

• get mpy-cross tool

  git clone https://github.com/micropython/micropython.git
  cd micropython/mpy-cross
  make

• optionally get heapsize of your board via repl.

  >>> import gc
  >>> gc.collect()
  >>> gc.mem_free()
  2812256
  

• compile source code and get .mpy file

  ./mpy-cross -X heapsize=2812256 blynklib_mp.py

• .mpy files in the same manner can be placed to board libs with ampy as usual .py file

  ampy put blynklib_mp.mpy /lib/blynklib_mp.mpy

  and then imported within user scripts as usual .py lib

  # start of user script
  import blynklib_mp

Wifi Connection

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()