Your Smart IOT

<p>The last time, we used the <strong>Arduino as a Web server</strong>. In the next few entries, we will aim to expand the Web server by building a Stevenson screen. While there are thermometers and hydrometers in a Stevenson screen, this time, we will be building a Stevenson screen for indoor use, using optical and ultrasonic sensors used previously, so that besides temperature and humidity, it is capable of sensing the indoor environment.</p>
<p><img alt="2014-08-29-14.53.39-e1409555341163" class="alignnone wp-image-522 size-full" height="394" src="http://ift.tt/1r81334" width="700" /></p>
<p>We aim to be able to store the data collected by the Stevenson screen in an SD card, and integrate it with a server-side program through the Web server.</p>
<p>In this article, we will se how to operate the temperature sensor with <a href="http://ift.tt/25oS3pH" itemprop="url" target="_bank" title="Arduino"><strong>Arduino</strong></a>. We will combine it with the Web server light sensor used previously.</p>
<h2>Today’s Electronics Recipe</h2>
<p>Estimated time to complete: 45 minutes<br />
Parts needed:</p>
<ul>
<li>Arduino (Arduino Uno R3) <a href="http://ift.tt/19qjkOK" target="_blank">http://ift.tt/19qjkOK</a></li>
<li>Breadboard <a href="http://ift.tt/1z7Tzip" target="_blank">http://ift.tt/1z7Tzip</a></li>
<li>Temperature sensor (LM35DZ)</li>
<li>7-segment <a href="http://ift.tt/1Rq2vDU" itemprop="url" target="_bank" title="LED"><strong>LED</strong></a> NAR161-B (high intensity red, 7-segment LED display, common anode)</li>
<li>Resistor (220Ω)</li>
</ul>
<h3>How to use the temperature sensor</h3>
<p>While there are many types of temperature sensors, we will be using the common LM35DZ.</p>
<p><img alt="2014-08-28-23.26.23-e1409555477202" class="alignnone size-full wp-image-523" height="394" src="http://ift.tt/1r811bt" width="700" /></p>
<p>Temperature sensor LM35DZ</p>
<p>Compared to other sensors, temperature sensors are easy to use. The LM35DZ is able to measure temperatures from 0℃ to 100℃, giving an output of 0V when the temperature is 0℃, 10mv at 1℃, and 100mV at 10℃.</p>
<p>As Arduino can receive analog inputs with values from 0 to 1023, it is possible to measure temperature using Arduino with the following formula.</p>
<p><strong>Temperature = (([Base voltage(5V)] * [input value from analog pin]) / 1024) * 100;</strong></p>
<p>Let’s connect this up to the Arduino.</p>
<p>The temperature sensor is connected as per the picture below.</p>
<p><img alt="5vs" class="alignnone size-full wp-image-524" height="369" src="http://ift.tt/1qAdcwP" width="700" /></p>
<p>With the flat part on top, from the left: +Vs, Vout, GND</p>
<p><img alt="fig" class="alignnone size-full wp-image-526" height="512" src="http://ift.tt/1r811bx" width="473" /></p>
<p><img alt="2014-08-29-02.22.13-e1409557281714" class="alignnone size-full wp-image-525" height="394" src="http://ift.tt/1qAdaVS" width="700" /></p>
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<div class="line number1 index0 alt2"><code class="cpp comments">//</code></div>
<div class="line number2 index1 alt1"><code class="cpp comments">// Program to display the temperature sensor value on serial monitor</code></div>
<div class="line number3 index2 alt2"><code class="cpp comments">//</code></div>
<div class="line number4 index3 alt1"><code class="cpp color1 bold">int</code> <code class="cpp plain">sensorPin = A0;</code> <code class="cpp comments">// using analog pin 0</code></div>
<div class="line number5 index4 alt2"><code class="cpp color1 bold">int</code> <code class="cpp plain">sensorValue = 0;</code></div>
<div class="line number6 index5 alt1"><code class="cpp keyword bold">void</code> <code class="cpp plain">setup() {</code></div>
<div class="line number7 index6 alt2"><code class="cpp plain">Serial.begin(9600);</code> <code class="cpp comments">// setting to display on serial monitor</code></div>
<div class="line number8 index7 alt1"><code class="cpp plain">}</code></div>
<div class="line number9 index8 alt2"><code class="cpp keyword bold">void</code> <code class="cpp plain">loop() {</code></div>
<div class="line number10 index9 alt1"><code class="cpp plain">sensorValue = analogRead(sensorPin);</code> <code class="cpp comments">// getting input from analog pin 0</code></div>
<div class="line number11 index10 alt2"><code class="cpp color1 bold">float</code> <code class="cpp plain">temp = modTemp(sensorValue);</code> <code class="cpp comments">// converting input values from the temperature sensor</code></div>
<div class="line number12 index11 alt1"><code class="cpp plain">Serial.println(temp);</code> <code class="cpp comments">// displaying results on serial monitor</code></div>
<div class="line number13 index12 alt2"><code class="cpp plain">delay(500);</code> <code class="cpp comments">// 0.5 second delay</code></div>
<div class="line number14 index13 alt1"><code class="cpp plain">}</code></div>
<div class="line number15 index14 alt2"><code class="cpp comments">// converting analog input value to ℃</code></div>
<div class="line number16 index15 alt1"><code class="cpp color1 bold">float</code> <code class="cpp plain">modTemp(</code><code class="cpp color1 bold">int</code> <code class="cpp plain">analog_val){</code></div>
<div class="line number17 index16 alt2"><code class="cpp color1 bold">float</code> <code class="cpp plain">v = 5;</code> <code class="cpp comments">// base voltage (V)</code></div>
<div class="line number18 index17 alt1"><code class="cpp color1 bold">float</code> <code class="cpp plain">tempC = ((v * analog_val) / 1024) * 100;</code> <code class="cpp comments">// conversion to Celsius</code></div>
<div class="line number19 index18 alt2"><code class="cpp keyword bold">return</code> <code class="cpp plain">tempC;</code></div>
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<p><img alt="f92b43078d19f73a01485426adea25ef-e1409557333163" class="alignnone size-full wp-image-527" height="505" src="http://ift.tt/1r811bB" width="700" /></p>
<p>Display on serial monitor</p>
<p>Using the serial monitor ([Tool]-[Serial monitor]), also used in the <a href="http://ift.tt/1qAdaVU" target="_blank">article about the light sensor</a>, to display the current temperature on the screen!</p>
<p>Looking at the program, besides the setup() and loop() functions, the modTemp() function also appears in the program. The process can be to some degree consolidated into functions.</p>
<h2>Structure of Functions</h2>
<p><strong>[return value type] [function name]([parameters]){</strong><br />
<strong>〜define the processing here〜</strong><br />
<strong>return [value to return];</strong></p>
<p>Example:</p>
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<div class="line number1 index0 alt2"><code class="cpp plain">loop(){</code></div>
<div class="line number2 index1 alt1"><code class="cpp color1 bold">int</code> <code class="cpp plain">result01 = testFunc(1,2);</code></div>
<div class="line number3 index2 alt2"><code class="cpp color1 bold">int</code> <code class="cpp plain">result02 = testFunc(3,4);</code></div>
<div class="line number4 index3 alt1"><code class="cpp plain">}</code></div>
<div class="line number5 index4 alt2"><code class="cpp color1 bold">int</code> <code class="cpp plain">testFunc(</code><code class="cpp color1 bold">int</code> <code class="cpp plain">A,</code> <code class="cpp color1 bold">int</code> <code class="cpp plain">B){</code></div>
<div class="line number6 index5 alt1"><code class="cpp color1 bold">int</code> <code class="cpp plain">C = A + B;</code></div>
<div class="line number7 index6 alt2"><code class="cpp keyword bold">return</code> <code class="cpp plain">C;</code></div>
<div class="line number8 index7 alt1"><code class="cpp plain">}</code></div>
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<p>Process flow and results: Calling of function “testFunc” within “loop”, and returning the results of the processing by “testFunc” in “result01” and “result02” based on the parameters passed. Value in “result01” is 3 and “result02” is 7.</p>
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<p>As the program gets longer, using functions will allow to consolidate the process, avoid the code repetitions, and make the change needed directly in the functions. So, let’s try to use functions when there is similar process to be carried out.</p>
<p>This is all we need to us the temperature sensor. Easy, right?</p>
<h2>Installation on the Web server</h2>
<p>Let’s install the temperature sensor on the Web server that we’ve built previously.</p>
<p> </p>
<p><img alt="lightsensor" class="alignnone size-full wp-image-528" height="548" src="http://ift.tt/1r811bD" width="518" /></p>
<p><img alt="2014-08-29-05.52.03-e1409570177197" class="alignnone size-full wp-image-529" height="394" src="http://ift.tt/1qAdcwT" width="700" /></p>
<p> </p>
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<div class="line number1 index0 alt2"><code class="cpp comments">//</code></div>
<div class="line number2 index1 alt1"><code class="cpp comments">// Program to display temperature sensor and <a href="http://ift.tt/1SDfTEN" itemprop="url" target="_bank" title="light"><strong>light</strong></a> sensor through the Web server</code></div>
<div class="line number3 index2 alt2"><code class="cpp comments">//</code></div>
<div class="line number4 index3 alt1"><code class="cpp preprocessor">#include <SPI.h></code></div>
<div class="line number5 index4 alt2"><code class="cpp preprocessor">#include <Ethernet.h></code></div>
<div class="line number6 index5 alt1"><code class="cpp plain">byte mac[] = {</code></div>
<div class="line number7 index6 alt2"><code class="cpp plain">0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };</code> <code class="cpp comments">// specifying the MAC address on the Ethernet shield</code></div>
<div class="line number8 index7 alt1"><code class="cpp plain">IPAddress ip(192,168,0,177);</code> <code class="cpp comments">// specifying the IP address assigned to the Arduino server</code></div>
<div class="line number9 index8 alt2"><code class="cpp plain">EthernetServer server(80);</code> <code class="cpp comments">// specifying the server port (no issue to keep as 80 as we are using HTTP)</code></div>
<div class="line number10 index9 alt1"><code class="cpp keyword bold">void</code> <code class="cpp plain">setup() {</code></div>
<div class="line number11 index10 alt2"><code class="cpp comments">// Open serial communications and wait for port to open:</code></div>
<div class="line number12 index11 alt1"><code class="cpp plain">Serial.begin(9600);</code></div>
<div class="line number13 index12 alt2"><code class="cpp keyword bold">while</code> <code class="cpp plain">(!Serial) {</code></div>
<div class="line number14 index13 alt1"><code class="cpp plain">;</code> <code class="cpp comments">// wait for serial port to connect. Needed for Leonardo only</code></div>
<div class="line number15 index14 alt2"><code class="cpp plain">}</code></div>
<div class="line number16 index15 alt1"><code class="cpp plain">Ethernet.begin(mac, ip);</code> <code class="cpp comments">// testing connection with Ethernet shield</code></div>
<div class="line number17 index16 alt2"><code class="cpp plain">server.begin();</code></div>
<div class="line number18 index17 alt1"><code class="cpp plain">Serial.print(</code><code class="cpp string">"server is at "</code><code class="cpp plain">);</code></div>
<div class="line number19 index18 alt2"><code class="cpp plain">Serial.println(Ethernet.localIP());</code></div>
<div class="line number20 index19 alt1"><code class="cpp plain">}</code></div>
<div class="line number21 index20 alt2"><code class="cpp keyword bold">void</code> <code class="cpp plain">loop() {</code></div>
<div class="line number22 index21 alt1"><code class="cpp plain">EthernetClient client = server.available();</code> <code class="cpp comments">// monitor for external connections to the server</code></div>
<div class="line number23 index22 alt2"><code class="cpp keyword bold">if</code> <code class="cpp plain">(client) {</code></div>
<div class="line number24 index23 alt1"><code class="cpp plain">Serial.println(</code><code class="cpp string">"new client"</code><code class="cpp plain">);</code></div>
<div class="line number25 index24 alt2"><code class="cpp comments">// an http request ends with a blank line</code></div>
<div class="line number26 index25 alt1"><code class="cpp plain">boolean currentLineIsBlank =</code> <code class="cpp keyword bold">true</code><code class="cpp plain">;</code></div>
<div class="line number27 index26 alt2"><code class="cpp keyword bold">while</code> <code class="cpp plain">(client.connected()) {</code></div>
<div class="line number28 index27 alt1"><code class="cpp keyword bold">if</code> <code class="cpp plain">(client.available()) {</code></div>
<div class="line number29 index28 alt2"><code class="cpp color1 bold">char</code> <code class="cpp plain">c = client.read();</code></div>
<div class="line number30 index29 alt1"><code class="cpp plain">Serial.write(c);</code></div>
<div class="line number31 index30 alt2"><code class="cpp keyword bold">if</code> <code class="cpp plain">(c ==</code> <code class="cpp string">'\n'</code> <code class="cpp plain">&& currentLineIsBlank) {</code></div>
<div class="line number32 index31 alt1"><code class="cpp comments">// send a standard http response header</code></div>
<div class="line number33 index32 alt2"><code class="cpp plain">client.println(</code><code class="cpp string">"HTTP/1.1 200 OK"</code><code class="cpp plain">);</code></div>
<div class="line number34 index33 alt1"><code class="cpp plain">client.println(</code><code class="cpp string">"Content-Type: text/html"</code><code class="cpp plain">);</code></div>
<div class="line number35 index34 alt2"><code class="cpp plain">client.println(</code><code class="cpp string">"Connection: close"</code><code class="cpp plain">);</code> <code class="cpp comments">// the connection will be closed after completion of the response</code></div>
<div class="line number36 index35 alt1"><code class="cpp plain">client.println(</code><code class="cpp string">"Refresh: 3"</code><code class="cpp plain">);</code> <code class="cpp comments">// refresh the page <a href="http://ift.tt/1UDKUyD" itemprop="url" target="_bank" title="How to automatically water your plants with the Raspberry Pi"><strong>automatically</strong></a> every 5 sec</code></div>
<div class="line number37 index36 alt2"><code class="cpp plain">client.println();</code></div>
<div class="line number38 index37 alt1"><code class="cpp plain">client.println(</code><code class="cpp string">"<!DOCTYPE HTML>"</code><code class="cpp plain">);</code></div>
<div class="line number39 index38 alt2"><code class="cpp plain">client.println(</code><code class="cpp string">"<html>"</code><code class="cpp plain">);</code></div>
<div class="line number40 index39 alt1"><code class="cpp comments">// A) input from each sensor</code></div>
<div class="line number41 index40 alt2"><code class="cpp comments">// input from optical sensor</code></div>
<div class="line number42 index41 alt1"><code class="cpp color1 bold">int</code> <code class="cpp plain">sensorReading = analogRead(0);</code> <code class="cpp comments">// analog pin 0</code></div>
<div class="line number43 index42 alt2"><code class="cpp plain">client.print(</code><code class="cpp string">"Light:"</code><code class="cpp plain">);</code></div>
<div class="line number44 index43 alt1"><code class="cpp plain">client.print(sensorReading);</code></div>
<div class="line number45 index44 alt2"><code class="cpp plain">client.println(</code><code class="cpp string">"<br />"</code><code class="cpp plain">);</code></div>
<div class="line number46 index45 alt1"><code class="cpp plain">delay(50);</code></div>
<div class="line number47 index46 alt2"><code class="cpp comments">// input from temperature sensor</code></div>
<div class="line number48 index47 alt1"><code class="cpp plain">sensorReading = analogRead(1);</code> <code class="cpp comments">// analog pin 1</code></div>
<div class="line number49 index48 alt2"><code class="cpp plain">client.print(</code><code class="cpp string">"Temp:"</code><code class="cpp plain">);</code></div>
<div class="line number50 index49 alt1"><code class="cpp plain">client.print(modTemp(sensorReading));</code></div>
<div class="line number51 index50 alt2"><code class="cpp plain">client.println(</code><code class="cpp string">"<br />"</code><code class="cpp plain">);</code></div>
<div class="line number52 index51 alt1"><code class="cpp plain">client.println(</code><code class="cpp string">"</html>"</code><code class="cpp plain">);</code></div>
<div class="line number53 index52 alt2"><code class="cpp keyword bold">break</code><code class="cpp plain">;</code></div>
<div class="line number54 index53 alt1"><code class="cpp plain">}</code></div>
<div class="line number55 index54 alt2"><code class="cpp keyword bold">if</code> <code class="cpp plain">(c ==</code> <code class="cpp string">'\n'</code><code class="cpp plain">) {</code></div>
<div class="line number56 index55 alt1"><code class="cpp comments">// you're starting a new line</code></div>
<div class="line number57 index56 alt2"><code class="cpp plain">currentLineIsBlank =</code> <code class="cpp keyword bold">true</code><code class="cpp plain">;</code></div>
<div class="line number58 index57 alt1"><code class="cpp plain">}</code></div>
<div class="line number59 index58 alt2"><code class="cpp keyword bold">else</code> <code class="cpp keyword bold">if</code> <code class="cpp plain">(c !=</code> <code class="cpp string">'\r'</code><code class="cpp plain">) {</code></div>
<div class="line number60 index59 alt1"><code class="cpp comments">// you've gotten a character on the current line</code></div>
<div class="line number61 index60 alt2"><code class="cpp plain">currentLineIsBlank =</code> <code class="cpp keyword bold">false</code><code class="cpp plain">;</code></div>
<div class="line number62 index61 alt1"><code class="cpp plain">}</code></div>
<div class="line number63 index62 alt2"><code class="cpp plain">}</code></div>
<div class="line number64 index63 alt1"><code class="cpp plain">}</code></div>
<div class="line number65 index64 alt2"><code class="cpp comments">// give the web browser time to receive the data</code></div>
<div class="line number66 index65 alt1"><code class="cpp plain">delay(1);</code></div>
<div class="line number67 index66 alt2"><code class="cpp comments">// close the connection:</code></div>
<div class="line number68 index67 alt1"><code class="cpp plain">client.stop();</code></div>
<div class="line number69 index68 alt2"><code class="cpp plain">Serial.println(</code><code class="cpp string">"client disonnected"</code><code class="cpp plain">);</code></div>
<div class="line number70 index69 alt1"><code class="cpp plain">}</code></div>
<div class="line number71 index70 alt2"><code class="cpp plain">}</code></div>
<div class="line number72 index71 alt1"><code class="cpp comments">// B) converting analog input value to ℃</code></div>
<div class="line number73 index72 alt2"><code class="cpp color1 bold">float</code> <code class="cpp plain">modTemp(</code><code class="cpp color1 bold">int</code> <code class="cpp plain">analog_val){</code></div>
<div class="line number74 index73 alt1"><code class="cpp color1 bold">float</code> <code class="cpp plain">v = 5;</code> <code class="cpp comments">// base voltage (V)</code></div>
<div class="line number75 index74 alt2"><code class="cpp color1 bold">float</code> <code class="cpp plain">tempC = ((v * analog_val) / 1024) * 100;</code> <code class="cpp comments">// conversion to Celsius</code></div>
<div class="line number76 index75 alt1"><code class="cpp keyword bold">return</code> <code class="cpp plain">tempC;</code></div>
<div class="line number77 index76 alt2"><code class="cpp plain">}</code></div>
</div>
</td>
</tr>
</tbody>
</table>
</div>
</div>
<p>The parts in red are what has changed from the program previously used for the Web server. Using part A to get the actual analog value (previously used for “for” statement), and part B to define the function to convert the temperature value, it is possible to display the values from the two sensors.</p>
<p>Once you are ready with the program, try displaying it in your browser.</p>
<p><img alt="6d3b02a0a26f9863ef645556093e4bbf" class="alignnone size-full wp-image-530" height="143" src="http://ift.tt/1r811rV" width="289" /></p>
<p>We are one step closer to our Stevenson screen!</p>
<h2>Display of Arduino Data</h2>
<p>After using Arduino, you may have realized that there are many methods for displaying data. You can use Arduino and display the data through parts such as LED, on a PC through serial monitors, via the Ethernet shield through a network, and etc. There are many display methods, but in this example, as we build the Stevenson screen, what would be an interesting way to display data obtained? After all the trouble to set up a Web server with an Ethernet shield, it would be interesting to be able to display the data on a smart phone.<br />
Whether it is interesting or boring depends on the display method. Let’s try displaying the input values using an electrical component known as a 7-segment LED.</p>
<p>* There will be a detailed explanation on how to use a 7-segment LED next time.</p>
<h2>Attempt to display the temperature sensor value on 7-segment LED</h2>
<p>When operating Arduino using power adapters, you cannot see the serial monitor. For those who want to see the sensor values immediately, try setting up a 7-segment LED. It can display the analog input value as a numerical value.</p>
<p><img alt="2014-08-29-05.10.12-e1409570497886" class="alignnone wp-image-531 size-full" height="394" src="http://ift.tt/1qAdcwX" width="700" /></p>
<p>7-segment LED</p>
<p><iframe width="678" height="381" src="https://www.youtube.com/embed/O0qd768FV1M?feature=oembed" frameborder="0" allowfullscreen=""></iframe></p>
<p>Testing a 7-segment LED using a test count-up program</p>
<h2>How to use a 7-segment LED</h2>
<p>Let’s try using the 7-segment LED to display the value of the temperature sensor. Trying to use the 7-segment LED as it is led to the value inside the circuit overflowing, making the Arduino into something like a bomb <img alt=":)" class="wp-smiley" src="http://ift.tt/1r813ju" /></p>
<p><iframe width="678" height="381" src="https://www.youtube.com/embed/wKIJIbcRWzY?feature=oembed" frameborder="0" allowfullscreen=""></iframe></p>
<p>Displaying the value of the temperature sensor using a 7-segment LED</p>
<p><img alt="2014-08-29-14.53.39-e1409555341163" class="alignnone size-full wp-image-532" height="394" src="http://ift.tt/1qAdcwZ" width="700" /></p>
<p>Final installation of temperature sensor and optical sensor</p>
<p>After installing the temperature sensor and the light sensor, the setup looks more complete. In the next article, we will be installing another sensor, and then we will be having a look at the case that will house the Arduino.</p>
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Make a Stevenson Screen with Arduino Part 1

The last time, we used the Arduino as a Web server . In the next few entries, we will aim to expand the Web server by building a Stevenson ...

Make a Stevenson Screen with Arduino Part 1

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