# Measure soil moisture - Virtual IoT Hardware In this part of the lesson, you will add a capacitive soil moisture sensor to your virtual IoT device and read values from it. ## Virtual Hardware The virtual IoT device will use a simulated Grove capacitive soil moisture sensor. This keeps the lab consistent with using a Raspberry Pi and a physical Grove capacitive soil moisture sensor. In a physical IoT device, the soil moisture sensor would be a capacitive sensor that measures soil moisture by detecting the capacitance of the soil, a property that changes as the soil's moisture level changes. As the soil moisture increases, the voltage decreases. This is an analog sensor, so it uses a simulated 10-bit ADC to report a value between 1 and 1,023. ### Add the soil moisture sensor to CounterFit To use a virtual soil moisture sensor, you need to add it to the CounterFit app. #### Task - Add the soil moisture sensor to CounterFit Add the soil moisture sensor to the CounterFit app. 1. Create a new Python app on your computer in a folder called `soil-moisture-sensor` with a single file named `app.py`, set up a Python virtual environment, and add the CounterFit pip packages. > ⚠️ You can refer to [the instructions for creating and setting up a CounterFit Python project in lesson 1 if needed](../../../1-getting-started/lessons/1-introduction-to-iot/virtual-device.md). 1. Make sure the CounterFit web app is running. 1. Create a soil moisture sensor: 1. In the *Create sensor* box in the *Sensors* pane, open the *Sensor type* dropdown and select *Soil Moisture*. 1. Leave the *Units* set to *NoUnits*. 1. Ensure the *Pin* is set to *0*. 1. Click the **Add** button to create the *Soil Moisture* sensor on Pin 0.  The soil moisture sensor will be created and appear in the sensors list.  ## Program the soil moisture sensor app The soil moisture sensor app can now be programmed using the CounterFit sensors. ### Task - Program the soil moisture sensor app Program the soil moisture sensor app. 1. Make sure the `soil-moisture-sensor` app is open in VS Code. 1. Open the `app.py` file. 1. Add the following code to the top of `app.py` to connect the app to CounterFit: ```python from counterfit_connection import CounterFitConnection CounterFitConnection.init('127.0.0.1', 5000) ``` 1. Add the following code to the `app.py` file to import some required libraries: ```python import time from counterfit_shims_grove.adc import ADC ``` The `import time` statement imports the `time` module, which will be used later in this assignment. The `from counterfit_shims_grove.adc import ADC` statement imports the `ADC` class to interact with a virtual analog-to-digital converter that can connect to a CounterFit sensor. 1. Add the following code below this to create an instance of the `ADC` class: ```python adc = ADC() ``` 1. Add an infinite loop that reads from this ADC on pin 0 and writes the result to the console. This loop can then sleep for 10 seconds between reads. ```python while True: soil_moisture = adc.read(0) print("Soil moisture:", soil_moisture) time.sleep(10) ``` 1. From the CounterFit app, change the value of the soil moisture sensor that will be read by the app. You can do this in one of two ways: * Enter a number in the *Value* box for the soil moisture sensor, then click the **Set** button. The number you enter will be the value returned by the sensor. * Check the *Random* checkbox, and enter a *Min* and *Max* value, then click the **Set** button. Every time the sensor reads a value, it will read a random number between *Min* and *Max*. 1. Run the Python app. You will see the soil moisture measurements written to the console. Change the *Value* or the *Random* settings to see the value change. ```output (.venv) ➜ soil-moisture-sensor $ python app.py Soil moisture: 615 Soil moisture: 612 Soil moisture: 498 Soil moisture: 493 Soil moisture: 490 Soil Moisture: 388 ``` > 💁 You can find this code in the [code/virtual-device](../../../../../2-farm/lessons/2-detect-soil-moisture/code/virtual-device) folder. 😀 Your soil moisture sensor program was a success! --- **Disclaimer**: This document has been translated using the AI translation service [Co-op Translator](https://github.com/Azure/co-op-translator). While we strive for accuracy, please note that automated translations may contain errors or inaccuracies. The original document in its native language should be regarded as the authoritative source. For critical information, professional human translation is recommended. We are not responsible for any misunderstandings or misinterpretations resulting from the use of this translation.