Team Group 11: Glen Powell, Tim Osterhoudt

Published April 21, 2023

MEGR 3171 Spring 2023 Group 11: Pool Sensor

This pool sensor is designed to take measurements of water temperature and pH level using a thermistor, pH sensor, and two Particle Argons.

BeginnerWork in progress12 hours18

MEGR 3171 Spring 2023 Group 11: Pool Sensor

Things used in this project

Hardware components

Adafruit Thermistor

Particle Argon

Jumper wires (generic)

pH Sensor

Adafruit Thermistor

Resistor 1k ohm

Resistor 330 ohm

LED (generic)

Software apps and online services

Particle Build Web IDE

ThingSpeak API

Hand tools and fabrication machines

3D Printer (generic)

Story

The Background

Problem this project solves:

The pool sensor uses two Argons with a thermistor and pH sensor to record the pool's water temperature and pH level. By doing this the Argons are able to send the temperature and pH data to Thing Speak or the user's phone. The thermistor allows the user to monitor the pool's temperature and see how cold or hot the water is and if it's ready to go in. While the pH sensor sends the pool's pH level to let the user know if the chlorine or salt levels in the pool are within the ranges they need to be. The devices can be stored in the box with a power supply to keep them protected at the poolside while the thermistor and pH sensor hang out of the slots to take measurements of the water.

Usefulness:

After having experimented with the device it was found that the data collected was easily accessible and was within acceptable ranges. With the thermistor, pH sensor, and LED's all working coherently together and sharing data. The devices provide a backup to any already installed temperature and pH sensors for pools, or could serve as a low-cost alternative. If the user had their pool monitors outside or on sperate devices such as a remote, the pool sensor using the two Argons provides an element convenience to the user. As they would have the data on their phone and recorded on Thing Speak making it more accessible. However, there were some issues encountered when developing the pool sensor with the Argons. The largest and most persistent was the pH sensor's reliability, the device required frequent recalibrations and would sometimes record the same sample at different pH levels with no changes to the device or sample. Although these issues were resolved a higher quality pH sensor is recommended.

Temperature sensor with LED lit.

In addition, it is commonly found that the ideal pool swimming temperature is between 25°C to 31°C (77°F to 81°F). While the pool pH level is best maintained between 7 to 7.6 pH.

Why would you want to use it:

When you live in Florida like Tim, owning a pool is a wonderful luxury to have in your backyard. On hot days during the summer going out and checking the temperature by hand, finding the remote, or waiting to get home to check the water can be a tiring or boring experience. The same goes for pool maintenance, making sure the pH levels are correct for the chlorine and salt requires going outside in the heat. Our device serves these two purposes. By providing convenience and serving as a backup to any already installed systems or as a low-cost alternative.

Box with components inside and lid on.

In addition to providing a low-cost solution for the role of a pool sensor, the box used to house the devices has sufficient space to hold any power supplies or any additional devices. The two slots provide a means of allowing both of the sensors individually hang from the box to access the pool. Or if needed provided a means of allowing power cords to enter while allowing sensors to access the the water outside the box. When needed all components can be stored inside of the box.

Box with lid off showing interior space.

What makes our solution novel:

Low-cost
Easy to use and build
Can fit into smaller containers if needed
Provides data throughout the day
Beginner friendly

How are our newly acquired IOT skills allowing usto bring such a solution alive:

For beginner's like us with the Particle Argon this project allowed for us to learn new skills while reinforcing old skills. After having worked on this project we learned how to use C++ to code our devices, and how to have two Argon's communicate with each other using publish and subscribe. While old skills developed in previous classes such as circuitry and problem solving were put to the test and reinforced.

How it Works

This device uses two sensors and two particle argons as well as an LED to display the status of one of the sensors. The first Particle Argon controls the pH sensor. Every ten seconds the pH sensor records the voltage output from the water read by the sensor. This is converted into the initial pH level before being converted again into the final pH level after taking into account the temperature data received from the other Particle Argon. The reasoning for this is the inverse relationship between water temperature and the pH level, as the higher the water temperature the lower the pH level. This final pH level is then sent to the temperature sensor where a LED will be lit if it falls within the specified range.

pH sensor and Argon device.

The second sensor records the temperature of the pool water. Every ten seconds the thermistor notices the drop in voltage over the resistor which is then converted to degrees Celsius. This temperature measurement is then sent to the pH sensor for the conversion process from voltage to pH level. Once the other Argon has received the temperature data it sends the pH data to the temperature sensor Argon which will light an LED if the pH level is out of the acceptable range warning the user in addition the data on their device.

Thermistor and Argon device.

Video

Video summarizing the project.

Live Data

The data recorded by the sensors is recorded through Thing Speak and can be seen here: Live Data Here

Temperature data graphed on Thing Speak.

Thing Speak showing the temperature data.

pH data graphed on Thing Speak.

Thing Speak showing the pH data.

Schematics

Code

// This #include statement was automatically added by the Particle IDE.
#include <ThingSpeak.h>
#include <math.h>
#include <Particle.h>

int ThermistorPin = A3;
int rPin=A2; //Red LED light for pH Level
int Vo; //Thermistor Voltage
int pH; //pH measurement from Tim's Argon
float pHr=0.0;
double R1 = 11010; //Thermistor Value 
double logR, R2, T, Tt; 
double c1 = 0.001061048, c2 = 0.00024125, c3= 0.0000000876741; //Calibration Constants 

TCPClient client; //Thingspeak Channel Information
unsigned long chanelID= 2110325; 
const char *myWriteAPIKey= "MY1552UHPFGPH62M";

void setup() {
    pinMode (ThermistorPin, INPUT);
    pinMode(rPin,OUTPUT);
  Particle.subscribe("pH", myHandler);//pull pH data from Tim's Argon 
 
}

void loop() {
  // Gets data from the Thermistor and converts it into usable temperature data
  Vo = analogRead(ThermistorPin);
  R2 = R1/(2000.0/((double)Vo-1));
  logR = log(R2);
  T = (1.0 / (c1 + (c2 * logR) + c3 *( logR * logR * logR)));
  Tt = T - 273.15; //Conv. to Celsius 
  pHr = pH;
 //ThingSpeak Live Data
 ThingSpeak.begin(client);
 int temperature=Tt;

ThingSpeak.setField(1,temperature);

ThingSpeak.writeField(chanelID, 1, temperature, myWriteAPIKey);
delay(20000); //delay 20 seconds
 
 //Publish To Cloud
 Particle.publish("temperature_C", String(Tt));
  // Wait 10 seconds
  delay(5000);

}

SerialLogHandler logHandler; //LED Warning Light turns on when pH is out of tollerance

void myHandler(const char *event, const char *data)
{

  pH = atoi(data);
  if (pH >= 0 && pH < 7) {
    digitalWrite(rPin, HIGH); // Green LED
  } else if (pH >= 7 && pH < 7.2) {
    digitalWrite(rPin, HIGH); // Green LED
    delay(500); // delay for 0.5 second
    digitalWrite(rPin, LOW); // turn off LED
    delay(500); // delay for 0.5 second
  } else if (pH >= 7.2 && pH < 7.4) {
    digitalWrite(rPin, HIGH); // Green LED
    delay(250); // delay for 0.25 second
    digitalWrite(rPin, LOW); // turn off LED
    delay(250); // delay for 0.25 second
  } else if (pH >= 7.4 && pH <= 7.6) {
    digitalWrite(rPin, LOW); // green LED
  } else if (pH > 7.6 && pH <= 8) {
    digitalWrite(rPin, HIGH); // Green LED
    delay(250); // delay for 0.25 second
    digitalWrite(rPin, LOW); // turn off LED
    delay(250); // delay for 0.25 second
  } else if (pH > 8 && pH <= 9) {
    digitalWrite(rPin, HIGH); // Green LED
    delay(500); // delay for 0.5 second
    digitalWrite(rPin, LOW); // turn off LED
    delay(500); // delay for 0.5 second
  } else if (pH > 9) {
    digitalWrite(rPin, HIGH); // Green LED
  }
}

// This #include statement was automatically added by the Particle IDE.
#include <ThingSpeak.h>
#include <math.h>
#include <Particle.h>

int V = A0; // set V to the analog pin connected to the pH sensor
float V2;
float pH;
float pH_conv;
float temperature_C;

TCPClient client; 
unsigned long chanelID= 2110325; 
const char *myWriteAPIKey= "MY1552UHPFGPH62M";


void setup() 
{ 
  Serial.begin(9600);
  pinMode(V, INPUT); 
  Particle.subscribe("temperature_C", updateTemperature, MY_DEVICES); // read data from GlenArgon
} 

void loop() 
{ 
  pH_conv = temperature_C * 0.0133; // conversion for effect of temperature on pH level

  V2 = analogRead(V) * (13.0 / 1024.0 / 6); // voltage conversion from sensor to pH

  pH = V2 - pH_conv; // conversion for final pH with temperature accounted for

  Serial.println(pH); // print pH level 
  delay(10000); 
  Particle.publish("pH", String(pH)); // publish pH level to GlenArgon to light LED if working
  
   //ThingSpeak Communication
 ThingSpeak.begin(client);
 int pHread=pH;

 ThingSpeak.setField(2,pH);

ThingSpeak.writeField(chanelID, 2, pHread, myWriteAPIKey); 
delay(20000); //Delay of 20 seconds
  
  
}

void updateTemperature(const char *event, const char *data) {
  temperature_C = atof(data); // convert the temperature value from string to float
}

Credits

Glen Powell

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Tim Osterhoudt

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MEGR 3171 Spring 2023 Group 11: Pool Sensor