Solar Minty + DHT22 + Waterproof DS18B20 + PH Probe

[andyx]

Solar powered Temperature corrected PH meter with Ambient Temperature and Humidity.

Display Shows Outside Temp and Humidity on top with PH and Water temp on bottom.

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[adafruit]

Intense! do you have a writeup, diagrams or code? would be an awesome example to show people what can be done with arduino!

[andyx]

I'll write something up with more info about it.

[adafruit]

awesome!

[andyx]

This is a work in progress project which uses a Solar charging MintyBoost to power an Arduino with a Proto Screw Shield on it. Attached is a 2X16 LCD using the I2C Backpack, a DHT22 Temperature and Humidity Sensor, a Waterproof DS18B20 Sensor and a 5V analog PH Probe/Adapter.

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LCDI2C_schem.jpg (75.08 KiB) Viewed 5401 times

Code: Select all

/*
Sketch combining DHT22, DS18B20 OneWire, LCD I2C and Analog PH 5V
Nothing very creative, but they all coexist no problem.
Make sure you visit each of these sensor's tutorials and get the required libraries.
*/

#include <Wire.h>
#include <LiquidCrystal.h>
#include <OneWire.h>
#include <DallasTemperature.h>
#include "DHT.h"

#define DHTPIN 11
#define DHTTYPE DHT22

DHT dht(DHTPIN, DHTTYPE);

#define ONE_WIRE_BUS 10
OneWire oneWire(ONE_WIRE_BUS);

DallasTemperature sensors(&oneWire);

int sensorPinPH = A0;

LiquidCrystal lcd(0);

void setup() {
 
  dht.begin();
 
  lcd.begin(16, 2); 
  lcd.setBacklight(HIGH);
  lcd.setCursor(8, 0);
 
  sensors.begin();
}

void loop() {
 
  float h = dht.readHumidity();
  float t = (dht.readTemperature()*9.0/5.0)+32.0;
  float sensorValue = 0;
  lcd.setCursor(0, 0);
  lcd.print(t);
  lcd.setCursor(8, 0);
  lcd.print(h);

  lcd.setCursor(0, 1);
 
  sensors.requestTemperatures();
   
  sensorValue = 7.0 - (2.5 - analogRead(sensorPinPH) / 204.8) / (0.257179 + 0.000941468 * sensors.getTempCByIndex(0));
  lcd.print(sensorValue);

  lcd.setCursor(8, 1);
  lcd.print((sensors.getTempCByIndex(0)*9.0/5.0)+32.0);
 
  delay(500);
}


[adafruit]

nice work! we'll post this up on our blog!

[senojcet]

What pH probe did you use? What is the BNC connector adapter board that you used? Thanks!

[andyx]

The adapter is a 1130 - pH/ORP Adapter from Phidgets.

The probe is a 3550 - ASP200-2-1M-BNC pH Lab Electrode.

Note that when using this sensor, formulas shown in the manual, need to be tweaked a bit. They use a 1000 analog input range, so adjust the formulas to work with the Arduino's 1024 analog input range.

[tmaros]

Hi!

It's an old post, but I hope someone could help me anyway. I'm trying to do aquarium controller, which should measure pH as well. I'm interfacing Arduino via LCD and buttons. I would like to have temperature compensated pH measurements, but also it would be nice to have calibration via LCD. My question is where did these "magic numbers" (in the quote) come from?

sensorValue = 7.0 - (2.5 - analogRead(sensorPinPH) / 204.8 ) / (0.257179 + 0.000941468 * sensors.getTempCByIndex(0));
lcd.print(sensorValue);

What is the meaning of 0.257179 or 0.000941468?
The equation is linear, but which numbers are supposed to stay the same and which should be changed when doing calibration?