Arduino Aquaponics EnvDAQ with Water Temperature Sensor

Introduction

The Environment DAQ is an open source Arduino shield used to track air temperature, relative humidity and light in aquaponic and hydroponic grow beds.  An equally important parameter to track is root temperature and with the new prototyping area on the v2 Environment DAQ boards, it is easy to add a new sensor.

The goal is to add the water temperature sensor to the other sensors on the Arduino  shield.

This tutorial requires that you have already completed the tutorials: Environment DAQ and Water Temperature.  You can download the complete source code here.

Part I:  Arduino

In Figures A and B you can see the Fritzing diagrams.  Figure A shows the full Environment DAQ with the DS18B20 integrated in and Figure B shows it solo.

Figure A.  Full EnvDAQ with DS18B20 to digital pin 5.

Figure B.  DS18B20 solo to digital pin 5.

To start upgrading the Arduino sketch, include the one-wire libraries and the sensor information.

Figure C.  Include statements and assignments.

The DS18B20 is a one-wire sensor, meaning you could run more than one sensor to the same digital port and differentiate the values using the device address.  At the bottom of the highlighted code in Figure C you will find the device address for our DS18B20 used for the this tutorial.  The link above it is a tutorial for finding the address of your specific sensor.

 Figure D shows a miscellaneous string used to temporarily hold the water temperature reading.

Figure D.  Temporary string for holding the water temperature reading.

In setup(), we need to add the commands to begin the sensor and set the resolution - Figure E.

Figure E.  setup() commands for the DS18B20

Each sensor in the main loop resets a string to blank, requests the data string from its function and outputs the new string to Serial.  You can comment out the Serial when you put this into operation.

Figure F.  DS18B20 loop() code.

 Next, add the string from Figure F to the end of the GAE request - Figure G.

Figure G.  Add the water temp string to the end of the web request.

Finally, create the function that gets the root temperature and converts it from Celsius to Fahrenheit and finally, to the string the web request uses.

Part II: App Engine

To make this process as easy as possible, cut and paste the temperature code and add a "w" or "W" in the places shown.  This will dramatically decrease the chances of typo errors and the time this upgrade takes.

UserPrefs Model & Settings Template
Open settings.py and edit the UserPrefs model.  Add in the properties for water temperature minimum and water temperature maximum preferences - Figure 1.  This is the first example of the suggestion above about copy and pasting the temperature property data; here, copy and paste and a "w" to the beginning.

Figure 1.  Water temperature min and max preferences.

Scroll down settings.py and add the form variables below the light properties.

Figure 2.  Water temperature variables for settings form.

The water temperature preferences are in a template (which we will create in a minute).  First, add the code from Figure 3 to render the (yet-to-be-created) water temperature template and pass in the preferences.

Figure 3.  Render the water temperature template.

The water temperature template is loaded into the /templates/settings/content.html template - the main settings template.  Edit the template rendering code to pass in the water temperature template - Figure 4.

Figure 4.  Pass the water temperature template into the main template.

Next, edit /templates/settings/content.html by adding in the template variable for the water temperature template from Figure 4.

Figure 5.  Edit content.html for the new water temperature template.

Finally, create the water temperature template: water_temp.html.  Again, this is easily done by copying and pasting the original temperature.html code and add the "w" in places.  The full template is in Figure 6.

Figure 6.  Water temperature template.

Launch the web application in the sandbox and go to Settings to check the templates are loading correctly.

Figure 7.  Water temperature template rendered in Settings tab.

Saving Water Temperature Preferences

To save the preferences for water temperature, start by creating the onclick handler in javascript.  Open settings.js, copy the original saveTempSettings() function and edit for water temperature - Figure 8.

Figure 8.  Onclick handler for water temperature save button.

The onclick handler makes an asynchronous request to the server, so we need a request handler to process the request.

Figure 9.  Request handler for water temperature form.

Add the new request handler to the bottom so the request is properly routed.

Figure 10.  Request handler link.

Finally, reload the settings page in the sandbox and save water temperature settings.

Environment.py:  EnvData Model

In environment.py, amend the data model to include the water temperature parameter.

Figure 11.  EnvData water temperature property.

Adacs.py:  Arduino Request Handler

The request handler for the Arduino is in adacs.py.  Start by getting the water temperature argument passed from the Arduino and assigning it to WTemp.  Optionally, you can add a logging command to spit out the data that is passed.

Figure 12.  Arduino argument.

Next, assign the WTemp argument to the WTemp property of the EnvData model created in Figure 11.

Figure 13.  Assign the new argument to the WTemp property  of the EnvData entity.

One of the major upgrades to the EnvDAQ cloud application is the use of memcache.  Memcache stores data in system memory for a limited time and is specifically used here to hold the current parameters sent by the Arduino in order to reduce datastore read operations.  The original ~17,000+ read operations have been cut by a third, reducing the system load (and the potential for the server to instantiate new instances) and speeds up response times from the browser to the server.  Similarly, user preferences are stored in memcache.

Append the EnvNow assignment to include WTemp, before it is put in memcache.

Figure 14.  EnvNow with water temperature reading.

Test the Arduino request handler by typing in the following url in your browser

localhost:8080/adacs/arduino?Temp=84.1&Humidity=69.8&AmbientLDR=850&WaterTemp=75.0

If everything is working, the application will return "Connected".  To confirm the data was saved, open the Admin Console (localhost:8000/)  and then open Datastore Viewer.

water_temp.js

Just as we have JavaScript files for temperature, relative humidity and light, we need one for water temperature.  Create a new file: /static/scripts/water_temp.js and add the following

// Shared Aspects
var WTData = [[Time, WaterTemp, Min, Max]];       // Data for all water temp visualizations
var wtempChartData;

// Main Table
var wtempTable;

// Chart
var wtempChart;
var wtempChartOptions;

// Gauge
var wtempGauge;
var wtempGaugeData;
var wtempGaugeOptions;



function drawWTempTable() {
     // Chart data
     wtempChartData = google.visualization.arrayToDataTable(WTData);
     
     // Assign new visualization to DOM element
     wtempTable = new google.visualization.Table(document.getElementById(wtempTable));
     
     // Draw Table
     wtempTable.draw(wtempChartData);
}     

function updateWTempTable(Time, TempValue, MinTemp, MaxTemp) {
     // Get the last row number
     var lastRow = wtempChartData.getNumberOfRows();
     
     // Get the value of the last row
     var timeStamp = wtempChartData.getValue(lastRow - 1, 0);
     
     //alert(timeStamp + + TempValue);
     if (timeStamp == Now) {
          wtempChartData.removeRow(0);
     }
     
     
     wtempChartData.addRow([Time, TempValue, MinTemp, MaxTemp]);
     wtempTable.draw(wtempChartData);     
     
}

/////////////////////////////////////////////////////////////////////////////////////////////////

function drawWTempChart() {
     wtempChart = new google.visualization.LineChart(document.getElementById(wtempChart));
     wtempChartOptions = {         
       animation: {duration: 1000, easing: out},
       backgroundColor: { fill: "none" }
     };
     wtempChart.draw(wtempChartData, wtempChartOptions);          
}


function updateWTempChart() {
     wtempChart.draw(wtempChartData, wtempChartOptions);
}

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