- Python is more user-friendly than C/C++
- Board can be remotely controlled via WebREPL in a real-time manner: Here is a Python client.
- ROM: Read-only memory. Everything that would not lost after power off the device stays here.
- Firmware: Codes in the rom.
- Bootloader:
- First part of firmware.
- First execute during power-up sequence (remain dormant thereafter)
- Responsible for guide rest of firmware.
- esptool: Tool that talks to Espressif boards' bootloader.
- By talking to bootloader, we can add or remove more codes in the rom. For example, operating system is "more codes"
- Change Linux user's group id so we gain the right to talking with bootloader.
sudo usermod -aG dialout $USER newgrp dialout - Flash: Adding more codes is called flashing because we are storing codes in flash memory.
To Raspberry Pi Pico [W] (Hello world)
- Connect Pico to PC via USB cable.
- A new removable media appears as RPI-RP2
- There is a pre-compiled micropython fireware, a downloadable UF2 file.
- Download the UF2 file into RPI-RP2.
- Pico will restart automatically then boot into micropython.
- A new serial port is now avaiable at /dev/ttyACM0
- Use screen to play with micropython (ported Python3.4)
# screen /dev/ttyACM0 115200
>>> import sys
>>> print(sys.version)
3.4.0
- Pico's MicroPython Docs
To ESP32
- Remove "more codes" (For some special board like Heltec Wireless Stick Lite, One has to bring down GPIO0 to flash the board)
pip install esptool
esptool.py --port /dev/ttyUSB0 erase_flash # Erase flash. Only bootload left in ROM
- Add "more codes" which is MicroPython
# https://micropython.org/download/esp32/
wget https://micropython.org/resources/firmware/esp32-20210902-v1.17.bin
esptool.py --port /dev/ttyUSB0 --chip esp32 write_flash -z 0x1000 esp32-20210902-v1.17.bin
- Hello World
$ screen /dev/ttyUSB0 115200
>>> import sys
>>> print(sys.version)
3.4.0
To ESP8266
- Flash MicroPython
esptool.py --port /dev/ttyUSB0 erase_flash
esptool.py --port /dev/ttyUSB0 --baud 460800 write_flash --flash_size=detect 0 esp8266-20210902-v1.17.binAll-in-One script: Flash ESP8266 and Enable WebREPL
wget https://micropython.org/resources/firmware/esp8266-20220618-v1.19.1.bin
bash flash_esp.sh --model esp8266 --port /dev/ttyUSB0 --bin esp8266-20220618-v1.19.1.bin --hostname myESP8266 --webrepl-passwd 123456 --ssid xxx --wifi-passwd xxxAccess ESP board Remotely (WebSocket)
- Setup WebREPL
- Flash MicroPython (>1.8.6)
- Use Serial Communication
screen /dev/ttyUSB0 115200 import webrepl_setup # >>> E (Press Shift + E Keys) # >>> 123456 (As WebREPL password)- Visit https://micropython.org/webrepl/ so one can connect to ESP board after step 4.
- Connect MicroPython's WiFi access point so the board can be accessed remotely.
- Access WebREPL when ESP board is in Station Mode
- Run following code via Serial Com to join the board to a WiFi network and it will be accessiable via WebSocket automatically even after reboot.
import network wlan = network.WLAN(network.STA_IF) wlan.active(True) wlan.config(dhcp_hostname="IwantThisHostname") wlan.connect('ssid', 'password') wlan.ifconfig() # ('192.168.x.128', '255.255.255.0', '192.168.x.x', '8.8.8.8') - Here is a Python client
- All in One
esptool.py --port /dev/ttyUSB0 erase_flash esptool.py --port /dev/ttyUSB0 --baud 460800 write_flash --flash_size=detect 0 esp8266-20210902-v1.17.bin screen -d -m -S esp8266 /dev/ttyUSB0 115200 screen -S esp8266 -X stuff "^M" screen -S esp8266 -X stuff "import webrepl_setup ^M" screen -S esp8266 -X stuff "E^M" screen -S esp8266 -X stuff "123456^M" screen -S esp8266 -X stuff "123456^M" screen -S esp8266 -X stuff "y^M" screen -S esp8266 -X stuff "^M" screen -S esp8266 -X stuff "import network ^M" screen -S esp8266 -X stuff "wlan = network.WLAN(network.STA_IF) ^M" screen -S esp8266 -X stuff "wlan.active(True) ^M" screen -S esp8266 -X stuff "wlan.config(dhcp_hostname='IRreceiver') ^M" screen -S esp8266 -X stuff "wlan.connect('SSID', 'PASSWORD') ^M" screen -S esp8266 -X stuff "wlan.ifconfig() ^M" screen -S esp8266 -X quit
Develop on a remote device --- esptool
- Caution: We are going to run esp_rfc2217_server.py and it listens tcp/4000 on 0.0.0.0
- Ref
- An ESP32 is attached to a remote raspberry "piMachine"
- The remote PiMachine has pySerial installed on it.
- Run on the client
wget https://raw.githubusercontent.com/espressif/esptool/master/esp_rfc2217_server.py
scp piMachine esp_rfc2217_server.py
# Start a remote screen session on pi
ssh piMachine "screen -S esp_rfc2217_server -d -m -s /bin/bash"
# Run esp_rfc2217_server in remote screen session so that piMachine:4000 is listening.
ssh piMachine "screen -S esp_rfc2217_server -X stuff \"python3 esp_rfc2217_server.py -p 4000 /dev/ttyUSB0 ^M\""
esptool.py --port rfc2217://piMachine:4000?ign_set_control --chip esp32 erase_flash
Use VScode as IDE
- Install VScode
- Search Pico-Go in extensions marketplace
- Create a folder so we can configure Pico-Go
- In Vscode's Command Palette, run "Pico-Go > Global settings".
- Change global settings' pico-go.json
{ "auto_connect": false } - In Vscode's Command Palette, run "Pico-Go > configurate project"
- Add new key and value in project's pico-go.json
{ "sync_folder": "", "open_on_start": true, "manual_com_device": "/dev/ttyACM0" } - Restart VScode
Run a script after boot
- Just name a script main.py instead of test.py and use rshell to upload
- When the board reboot, the script will run.
Paste code into REPL in screen (Better to use VScode)
Use jupyter-notebook instead of screen (Better to use VScode)
- Add MicroPython Kernel
pip install jupyter_micropython_kernel
python -m jupyter_micropython_kernel.install
Use rshell for file upload (Better to use VScode)
- Prepare a lib on Desktop
cat << EOF > test.py
def hello_world():
print("Hello World!")
EOF- Use rshell to transfer file
rshell -p /dev/ttyACM0 cp test.py /pyboard- Import lib
>>> import test
>>> test.hello_world()
Hello World!
- ENOMEM: Not enough memory
- create output pin on GPIO14
from time import sleep
from machine import Pin
p = Pin(14, Pin.OUT, value=0)
p.value(1)