It's easy to use the seesaw soil sensor with Python or CircuitPython and the Adafruit CircuitPython seesaw module. This module allows you to easily write Python code that reads the moisure/temperature from the sensor.
You can use this sensor with any CircuitPython microcontroller board or with a computer that has GPIO and Python thanks to Adafruit_Blinka, our CircuitPython-for-Python compatibility library.
CircuitPython Microcontroller Wiring
First wire up the soil sensor to your board exactly as shown on the previous pages for Arduino. Here's an example of wiring a Feather M0 to the sensor with I2C:
- Board 3V to sensor VIN
- Board GND to sensor GND
- Board SCL to sensor SCL
- Board SDA to sensor SDA
Python Computer Wiring
Since there's dozens of Linux computers/boards you can use we will show wiring for Raspberry Pi. For other platforms, please visit the guide for CircuitPython on Linux to see whether your platform is supported.
Here's the Raspberry Pi wired with I2C:
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CircuitPython Installation of seesaw Library
You'll need to install the Adafruit CircuitPython seesaw library on your CircuitPython board.
First make sure you are running the latest version of Adafruit CircuitPython for your board.
Next you'll need to install the necessary libraries to use the hardware--carefully follow the steps to find and install these libraries from Adafruit's CircuitPython library bundle. For example the Circuit Playground Express guide has a great page on how to install the library bundle for both express and non-express boards.
Remember for non-express boards like the Trinket M0, Gemma M0, and Feather/Metro M0 basic you'll need to manually install the necessary libraries from the bundle:
- adafruit_seesaw.mpy
- adafruit_bus_device
You can also download the adafruit_seesaw.mpy from its releases page on Github.
Before continuing make sure your board's lib folder or root filesystem has the adafruit_seesaw.mpy, and adafruit_bus_device files and folders copied over.
Next connect to the board's serial REPL so you are at the CircuitPython >>> prompt.
Python Installation of seesaw Library
You'll need to install the Adafruit_Blinka library that provides the CircuitPython support in Python. This may also require enabling I2C on your platform and verifying you are running Python 3. Since each platform is a little different, and Linux changes often, please visit the CircuitPython on Linux guide to get your computer ready!
Once that's done, from your command line run the following command:
sudo pip3 install adafruit-circuitpython-seesaw
If your default Python is version 3 you may need to run 'pip' instead. Just make sure you aren't trying to use CircuitPython on Python 2.x, it isn't supported!
CircuitPython & Python Usage
This example sketch shows connecting to the sensor and reading temperature and moisture/capacitive measurement
import time
from board import SCL, SDA
import busio
from adafruit_seesaw.seesaw import Seesaw
i2c_bus = busio.I2C(SCL, SDA)
ss = Seesaw(i2c_bus, addr=0x36)
while True:
# read moisture level through capacitive touch pad
touch = ss.moisture_read()
# read temperature from the temperature sensor
temp = ss.get_temp()
print("temp: " + str(temp) + " moisture: " + str(touch))
time.sleep(1)
Try touching the body of the sensor to make the 'moisture' measurement go up. In soil, you'll see this range from about 300 to 500, but make sure to test it by placing in a pot of soil and looking at the serial console to get an idea of what the range is. Note that it does depend on how packed/loose the soil is!
The temperature reading is only on the chip itself. It's not terribly precise but it is within a few degrees. Good for getting a basic sense of how the temperature is moving around the house
