Water my Basil plant

We wanted to grow some herbs at home and ensure they are well watered. So, we started with a low maintenance herb, the Basil Plant. Using a Grove soil moisture, it sends the sensor value every 30 minutes and shows it to water when the soil moisture gets below a certain level.

Wire up the Hardware

Hardware requirement is only the Grove soil moisture sensor, a Particle Photon and a breadboard. Take note of the Photon's Device ID and Access Token. Wiring up is really easy with just 3 pins from the soil moisture sensor:

• Pin VIN on Photon to VCC on soil moisture sensor

• Pin GND on Photon to GND on soil moisture sensor

• Pin A0 on Photon to SIG on soil moisture sensor

Finally connect the Particle Photon to a power source via the USB cable.

Flash the Firmware

Flash the firmware on Photon

int analogvalue = 0;
void setup()
{
 pinMode(D7, OUTPUT);
 if (Particle.variable("moisture", analogvalue) == false) {
   digitalWrite(D7, HIGH);
 }
 pinMode(A0, INPUT);
}
void loop()
{
 analogvalue = analogRead(A0);
 delay(200);
}

As you can see from the code above, it will publish a variable called moisture. You can also curl this value from the command line. Remember to replace the {DEVICE_ID} and {ACCESS_TOKEN} which your Photon's values.

curl "https://api.particle.io/v1/devices/{DEVICE_ID}/moisture?access_token={ACCESS_TOKEN}"

Start the Web Server

The web server will query this moisture sensor value every 30 minutes and will push the values on a web page. To setup the web server on your laptop you can follow these steps:

• Ensure Nodejs is installed in your laptop

• Clone the repository with git clone https://github.com/sayanee/cosmic

• Setup the environment variables on file .env

• Install all the Node packages with npm i

• Start the server with npm start

• View the webpage on your laptop at localhost:1337