lcarnevale / upy-driver-yl69

MicroPython driver of the resistive soil moisture sensor (YL-69, HL-69)

Resistive Soil Moisture Driver in MicroPython

This project contains a MicroPython driver for the resistive soil moisture sensor (YL-69 or HL-69), which measures the volumetric water content in soil, providing in output the voltage value.

The picture below shows the proper operation of the sensor. A lower output voltage is the result of sensing a wet soil, whereas a higher output voltage is the result of sensing a dry soil.

Before to start

Resolve the project dependecies by using the collected requirements.

$ virtualenv -p python3 venv
$ source venv/bin/activate
$ pip install -r requirements

Install picocom, a minimal dumb-terminal emulation program that is great for accessing a serial port based Linux console.

$ sudo apt-get install picocom

Plug the device to your PC and flash a clean micropython firmware. I am using an ESP-WROOM-32. After plugging the device, it typically appears on /dev/ttyUSB0. Try another enumeration otherwise, but be sure the USB cable you are using is a data cable (not energy only).

$ esptool.py --port /dev/ttyUSB0 erase_flash
$ esptool.py --chip esp32 --port /dev/ttyUSB0 write_flash -z 0x1000 /PATH/OF/FIRMWARE

For more information about how flashing MicroPython on ESP32-based device, see the MicroPython official documentation here.

Upload the MicroPython script

Put all files in the board by using the ampy tool as follow.

$ ampy --port /dev/ttyUSB0 put examples/boot.py
$ ampy --port /dev/ttyUSB0 put examples/main.py
$ ampy --port /dev/ttyUSB0 put drivers

For more information about how using the ampy tool, see the official documentation here.

Monitor your application

Monitor the application's output by using the picocom tool.

$ picocom -b 115200 -r -l /dev/ttyUSB0

To quit picocom use CTRL+A CTRL+X.

Troubleshooting

sudo chmod 666 /dev/ttyUSB0

Credits

1. Guide for Soil Moisture Sensor YL-69 or HL-69 with Arduino, Random Nerd Tutorials