Published November 25, 2017 © GPL3+

Plant Saver

Don't you just hate when you buy a nice house plant, forget to water it and within a week or two it dies. We have a solution for you!

BeginnerShowcase (no instructions)2.5 hours2,591

Things used in this project

Hardware components

Particle Photon

SparkFun Soil Moisture Sensor (with Screw Terminals)

Breadboard (generic)

Jumper wires (generic)

Depending on how long of a connection you need, the amount of wires used can vary

Software apps and online services

ThingSpeak API

IFTTT Maker service

Story

Plant Saver

This project was designed to help those of us who struggle with remembering to water their house plants on a regular basis. We start out with good intentions but life gets busy and those plants seem to take a place on the back burner of our minds. They aren't like a cat or dog or even a child who can let you know when they need something, so we have come up with an idea to give these plants a voice. It's nothing fancy, just two photons and a soil moisture monitor.

Project Basics

Both Photons are connected to small breadboards of their own, but only one photon will be directly connected to the soil moisture monitor. The soil moisture monitor will be connected through the A0, D7, and the GND pins of the photon. The plan is for one photon to collect the soil moisture data and send it to Thingspeak while the second photon will read this data and send a notification to the smartphone, via email, to let you know the plant needs to be watered. Since the soil moisture level is not in need of constant monitoring we want the notifications to only come whenever the soil is considered dry. House plants generally only need to be watered once a day in order to thrive in their environment. The photon will be programmed to take readings every ten minutes instead of updating constantly. This delay time will hopefully reduce the amount of time that the photon and soil moisture monitor will have to be running, thus reducing the battery usage for the moniter which will extend its lifetime. If the reading determines the plant needs to be watered then a notification will be sent; however, if the plant does not need water then a notification will not be sent. When running the project my photon is located in Bessemer City, NC while Daniel's photon is located in Charlotte, NC. There is a distance of about 36 miles between the photons while the project is running and collecting data. This goes to show that the photons do not have to be directly beside each other to work and send data over the internet to each other.

Programming

This project uses ThingSpeak and IFTTT, which require additional accounts to use. It should be noted that this requires a Web hook to work properly, and that creating this is not covered in this project. IFTTT is very straight forward, and once linked to your Particle account, you simply run the code at least once so that the variable appears on the IFTTT website in order to use it. From here, phone notifications, texts, emails, Tweets, and more can be sent if the moisture level falls below 50. It is also important to note that the dry level can vary based on the voltage being supplied to the Photon, and the soil being used. It's recommended to calibrate the sensor when you use it yourself!

VVideo

Sorry for the poor video quality. For the video purposes the photon was connected to the laptop as a power source. If we want to have a constant power source then we can use an Iphone power block to connect the photon set up to the wall outlet and let it run for an extended amount of time.

Pictures

Here are some of the graphs from ThingSpeak of the plant soil moisture data readings. We have assigned a range of numbers to indicate whether or not the soil is considered wet or dry. So, 0-35 is dry and the plant needs water and 35-70 is wet so the plant does not need to be watered. It's important to note that these numbers will likely be different for everyone, depending on the soil composition as well as the voltage being supplied to the sensor. Supplying 3.3 volts from the Photon will render lower values than if 5 volts were being supplied. Also, for general usage, we recommend taking samples every 10 minutes, however, for testing it's more practical to take samples every 60 seconds.

A Small Sample of Data Recorded To ThingSpeak

Code

int soilPin = A0;//read pin A0
int soilPower = 7;//gives power to D7 (has an LED on Photon - You can clearly see when it takes a value this way. Good for troubleshooting.)
int value = readSoil();//starts readSoil() function below
#define publish_delay 600000//publish every 10 minutes
unsigned int lastPublish = 0;//sets time since last publish to an initial value of 0
void setup() {
    pinMode(soilPower, OUTPUT);//sets D7 as an OUTPUT
    digitalWrite(soilPower, LOW);//turns D7 off
    //Spark.variable for particle
    //"Moisture" is the name you're looking out for when you're using IFTTT
    //&value is the variable you're using from your code to send using IFTTT
    Spark.variable("Moisture", &value, INT);//sets Spark.variable to Moisture, with the value from variable "value". For use with IFTTT applet
}
void loop() {
    unsigned long now = millis(); 
    if ((now - lastPublish) < publish_delay) {
        return;
    }
    int value = readSoil();//Calls function from below
    //Publishes the event "thingSpeakWrite_A0" to the Particle Cloud
    Particle.publish("thingSpeakWrite_A0", "{ \"1\": \"" + String(value) + "\", \"k\": \"EX4AMP13-REPLACE-WITH-YOUR-WRITE-KEY\" }", 60, PRIVATE);//publishes to ThingSpeak
    lastPublish = now;//resets lastPublish variable to now (resets timer)
}
int readSoil()
{
    digitalWrite(soilPower, HIGH);//turn D7 "On"
    delay(50);//wait 50 milliseconds 
    int val = analogRead(soilPin);//Read the SIG value form sensor 
    delay(50);//wait 50 milliseconds 
    digitalWrite(soilPower, LOW);//turns D7 off
    return val;//send current moisture value
}

int num = Particle.subscribe("thingSpeakWrite_A0", MoistureNotify, "YOUR-DEVICE-ID#");
void setup() {
    Particle.subscribe("thingSpeakWrite_A0", MoistureNotify, "YOUR-DEVICE-ID#");
    Spark.variable("MoistureLvl", &num, INT);
}
void loop() {
}
void MoistureNotify(const char *event, const char *data)
{
    int num = atoi(data);
    if (num<=100) {
      digitalWrite(D7,HIGH);
    }else if (num>100 && num<200) {
      digitalWrite(D7,LOW);
    }else {
      digitalWrite(D7,LOW);
  }
}