Your Smart IOT

<h2>1 Overview</h2>
<p>I left off having hopefully shown just how easy it is to get turn on an <a href="http://bit.ly/1WT6RcH" itemprop="url" target="_bank" title="LED"><strong>LED</strong></a> on the <a href="http://bit.ly/26nCm2K" itemprop="url" target="_bank" title="Raspberry"><strong>Raspberry</strong></a> Pi. First up I’m going to show a quick Blinky example, for now I’m going to stick with just using <a href="http://bit.ly/1WT6RcI" itemprop="url" target="_bank" title="Raspberry Pi GPIO Pins and Python"><strong>python</strong></a> in interactive mode form the terminal, but we may get into script files after I show the basic’s of inputs.</p>
<p> </p>
<h2><a name="2"></a>2 Blink on the Pi</h2>
<p>Straight in with the the code then:</p>
<pre class="brush:bash">
$ sudo python
>>> from time import sleep
>>> import RPi.GPIO as GPIO
>>> GPIO.setup(18, GPIO.OUT)
>>> while 1:
...     GPIO.output(18, False)
...     sleep(1)
...     GPIO.output(18, True)
...     sleep(1)
...
</pre>
<p> </p>
<p><a href="http://bit.ly/1qUAuO3" target="_blank"><img alt="" height="474" src="http://bit.ly/1qUAuO3" title="GPIO Code 3" width="672" /></a></p>
<p>So a little more to that than before, notice the prompt changed after the</p>
<pre class="brush:bash">
while 1:
</pre>
<p>to</p>
<pre class="brush:bash">
...
</pre>
<p>After this we need to indent the code with a tab for it to be considered part of the loop. Hit enter twice after the</p>
<pre class="brush:bash">
sleep(1)
</pre>
<p>and we now have a blinking red <a href="http://bit.ly/1UhB2tm" itemprop="url" target="_bank" title="LED"><strong>LED</strong></a> <img alt=":)" class="wp-smiley" src="http://bit.ly/1VNqWSO" style="height: 1em; max-height: 1em;" /></p>
<p>Now to stop the loop and get back to the <a href="http://bit.ly/1UhAZOh" itemprop="url" target="_bank" title="How to Build a Basic Web Crawler in Python"><strong>python</strong></a> prompt use Ctrl-C and to get out of python and back to the bash prompt you can use Ctrl-D. Below you can see I just used Ctrl-C to get back to the python prompt<br />
<a href="http://bit.ly/21fu8FY" target="_blank"><img alt="" height="474" src="http://bit.ly/21fu8FY" title="GPIO Code 4" width="672" /></a></p>
<p> </p>
<h2><a name="3"></a>3 Inputs</h2>
<p>Time to play with the push buttons, here the code again, if you are at the python prompt from above then just ignore the first two lines:</p>
<pre class="brush:bash">
 $ sudo python
>>> import RPi.GPIO as GPIO
>>> GPIO.setup(11, GPIO.IN)
>>> GPIO.input(11)
</pre>
<p> </p>
<p>Now we should get back a</p>
<pre class="brush:bash">
False
</pre>
<p>as below<br />
<a href="http://bit.ly/1WT6TBh" target="_blank"><img alt="" class="alignnone size-full wp-image-382" height="474" src="http://bit.ly/1WT6TBh" title="GPIO Code 5" width="672" /></a></p>
<p>Try holding down the button and doing that last line again</p>
<pre class="brush:bash">
>>> GPIO.input(11)
</pre>
<div class="ezAdsense adsense adsense-midtext" style="text-align:center;margin:12px;"><script async="" src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js" type="text/javascript">
</script> <ins class="adsbygoogle" style="display:block" data-ad-client="ca-pub-2979805726071943" data-ad-slot="7471922310" data-ad-format="auto"></ins> <script type="text/javascript">
//<![CDATA[
(adsbygoogle = window.adsbygoogle || []).push({});
//]]>
</script></div>
<p> </p>
<p>This time you should get back</p>
<pre class="brush:bash">
True
</pre>
<p>Now lets see if we can’t combine inputs and outputs</p>
<p> </p>
<h2><a name="4"></a>4 Combining Inputs and Outputs</h2>
<p>Ill give the full code example again:</p>
<pre class="brush:bash">
$ sudo pyton
>>> import RPi.GPIO as GPIO
>>> GPIO.setup(18, GPIO.OUT)
>>> GPIO.setup(11, GPIO.IN)
>>> while 1:
...     if GPIO.input(11):
...         GPIO.output(18, False)
...     else:
...         GPIO.output(18, True)
...
</pre>
<p> </p>
<p><a href="http://bit.ly/1qUAvS9" target="_blank"><img alt="" height="474" src="http://bit.ly/21fuah7" title="GPIO Code 6" width="672" /></a><br />
Now have a simple push button turning on an LED</p>
<p> </p>
<h2><a name="5"></a>5 Something a little more complex</h2>
<p>So it’s time to move onto something a little more complex and for this I’m going to start using a IDE called Geany, its already available on the Pi’s and has been used in some great youtube videos by Liam, check out his channel <a href="http://www.youtube.com/user/RaspberryPiTutorials" target="_blank">RaspberryPiTutorials</a></p>
<p>There are however a few limits to using geany, first we need to install xterm (at least on the debian image)</p>
<pre class="brush:bash">
$ sudo apt-get install xterm
</pre>
<p> </p>
<p>The second is a little more tricky, using RPi.GPIO needs root permission, hence we have been using sudo python up till now, luckily we can ask geany todo the same. Open geany form the <a href="http://bit.ly/1UhB04w" itemprop="url" target="_bank" title="Programming"><strong>Programming</strong></a> menu, once it loads, we want a new file from the main.py template, try the little down arrow at the side of the ‘New’ button.<br />
This should give us an untitled.py file pre filled with a load of text, we will go back to that in a bit. Next click on the ‘Build’ menu and then ‘Set Build Commands’. In the ‘Execute’ box near the bottom add the word “sudo” in front of the ‘python “%f” and hit ‘OK’</p>
<p><a href="http://bit.ly/21fu8G2" target="_blank"><img alt="" height="489" src="http://bit.ly/21fu8G2" title="Geany_1" width="590" /></a></p>
<p>Now back to that file in the editor, lets delete everything but the first line #!/usr/bin/env python and type in some code, lets try out our button to led example from above:</p>
<p><a href="http://bit.ly/1UhB04z" target="_blank"><img alt="" height="208" src="http://bit.ly/21fuahb" title="Geany_2" width="300" /></a></p>
<p>Now hit the ‘Execute’ button (3 little gears) and a black window pops up in which the python script will run and we have our push button LED again. But I wired up 4 LED’s and two Buttons so lets get them all working together:</p>
<pre class="brush:bash">
#!/usr/bin/env python
from time import sleep
# get the GPIO Library
import RPi.GPIO as GPIO
 
# setup some names references to the LED's and buttons
# red     = pin 18
# yellow  = pin 16
# green   = pin 15
# blue    = pin 13
 
# using an list to hold the led numbers
leds = [13, 15, 16, 18]
# the input buttons
up = 12
down = 11
 
# setup the pins as output and input as needed
# looping over the list 
for n in leds:
    GPIO.setup(n, GPIO.OUT)
 
GPIO.setup(up, GPIO.IN)
GPIO.setup(down, GPIO.IN)
# turn off all but the blue LED
GPIO.output(leds[3], True)
GPIO.output(leds[2], True)
GPIO.output(leds[1], True)
GPIO.output(leds[0], False)
 
#state trackers
level = 0
oldlevel = level
 
while 1:
    if GPIO.input(up):
        #up button pressed
        if level < 3:
            level += 1
    elif GPIO.input(down):
        #down button pressed
        if level > 0:
            level -= 1
    if oldlevel != level:
        # turn off last led and turn on next one
        GPIO.output(leds[oldlevel], True)
        GPIO.output(leds[level], False)
        # update state tracker
        oldlevel = level
        # sleep for a bit so button press is counted only once
        sleep(1)
</pre>
<p> </p>
<p>Try it out, file is <a href="http://bit.ly/1WT6TBm" target="_blank">here</a>, if all goes well the blue LED will light up and clicking the up button will change it to the green, and so on.</p>
<p>Another long post but should give an idea of how easy it can be to use the GPIO’s on the Raspberry Pi with a little Python.<br />
Next I’ll be looking at either the little Charlieplex LED display I built on another slice or it will be about using the XRF and URF radio modules with pyserial. Here’s some pics <img alt="😉" class="wp-smiley" src="http://bit.ly/1XRgdUu" style="height: 1em; max-height: 1em;" /><br />
<a href="http://bit.ly/1UhB2JJ" target="_blank"><img alt="" height="225" src="http://bit.ly/21fuahd" title="Charlieplex" width="300" /></a><br />
<a href="http://bit.ly/1WT6TBp" target="_blank"><img alt="" height="225" src="http://bit.ly/21fu8G4" title="XRF_URF" width="300" /></a></p>
<p> </p>
<div id="huge-it-share-buttons-top" class="huge-it-share-buttons nobackground">
<h3>Share This:</h3>
<ul class="huge-it-share-buttons-list">
<li class=" nobackground"><a href="http://bit.ly/1XReO0c" id="backforunical590" name="backforunical590" onclick="javascript:void window.open('http://bit.ly/1XReO0c','1410949501326','width=700,height=500,toolbar=0,menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');return false;" style="background-position: -0px -120px" target="_blank"></a></li>
<li class=" nobackground"><a href="https://twitter.com/share?status=http://yoursmart.mobi/feed&text=Raspberry%20Pi%20GPIO%20Inputs%20in%20Python" id="backforunical590" name="backforunical590" onclick="javascript:void window.open('https://twitter.com/share?status=http://yoursmart.mobi/feed&text=Raspberry Pi GPIO Inputs in Python','1410949501326','width=700,height=500,toolbar=0,menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');return false;" style="background-position: -30px -120px" target="_blank"></a></li>
<li class=" nobackground"><a href="http://bit.ly/1WT6RsY%20Pi%20GPIO%20Inputs%20in%20Python" id="backforunical590" name="backforunical590" onclick="javascript:void window.open('http://bit.ly/1WT6RsY Pi GPIO Inputs in Python','1410949501326','width=700,height=500,toolbar=0,menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');return false;" style="background-position: -60px -120px" target="_blank"></a></li>
<li class=" nobackground"><a href="http://bit.ly/1XReO0d" id="backforunical590" name="backforunical590" onclick="javascript:void window.open('http://bit.ly/1XReO0d','1410949501326','width=700,height=500,toolbar=0,menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');return false;" style="background-position: -90px -120px" target="_blank"></a></li>
<li class=" nobackground"><a href="http://bit.ly/1qUAv4w%20Pi%20GPIO%20Inputs%20in%20Python&mini=true&url=http://bit.ly/1XReO0g" id="backforunical590" name="backforunical590" onclick="javascript:void window.open('http://bit.ly/1qUAv4w Pi GPIO Inputs in Python&mini=true&url=http://bit.ly/1XReO0g','1410949501326','width=700,height=500,toolbar=0,menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');return false;" style="background-position: -120px -120px" target="_blank"></a></li>
<li class=" nobackground"><a href="http://bit.ly/1WT6TRE%20Pi%20GPIO%20Inputs%20in%20Python" id="backforunical590" name="backforunical590" onclick="javascript:void window.open('http://bit.ly/1WT6TRE Pi GPIO Inputs in Python','1410949501326','width=700,height=500,toolbar=0,menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');return false;" style="background-position: -150px -120px" target="_blank"></a></li>
<li class=" nobackground"><a href="http://di.gg/1qUAw8H%20Pi%20GPIO%20Inputs%20in%20Python" id="backforunical590" name="backforunical590" onclick="javascript:void window.open('http://di.gg/21fu8G7 Pi GPIO Inputs in Python','1410949501326','width=700,height=500,toolbar=0,menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');return false;" style="background-position: -180px -120px" target="_blank"></a></li>
<li class=" nobackground"><a href="http://stumble.it/1WT6TRG%20Pi%20GPIO%20Inputs%20in%20Python" id="backforunical590" name="backforunical590" onclick="javascript:void window.open('http://stumble.it/1WT6TRG Pi GPIO Inputs in Python','1410949501326','width=700,height=500,toolbar=0,menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');return false;" style="background-position: -210px -120px" target="_blank"></a></li>
<li class=" nobackground"><a href="http://bit.ly/1XReO0l" id="backforunical590" name="backforunical590" onclick="javascript:void window.open('http://bit.ly/1XReO0l','1410949501326','width=700,height=500,toolbar=0,menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');return false;" style="background-position: -240px -120px" target="_blank"></a></li>
<li class="none nobackground"><a href="http://bit.ly/1qUAvSg%20Pi%20GPIO%20Inputs%20in%20Python" id="backforunical590" name="backforunical590" onclick="javascript:void window.open('http://bit.ly/1qUAvSg Pi GPIO Inputs in Python','1410949501326','width=700,height=500,toolbar=0,menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');return false;" style="background-position: -270px -120px" target="_blank"></a></li>
<li class="none nobackground"><a href="http://bit.ly/1WT6Rt1%20Pi%20GPIO%20Inputs%20in%20Python" id="backforunical590" name="backforunical590" onclick="javascript:void window.open('http://bit.ly/1WT6Rt1 Pi GPIO Inputs in Python','1410949501326','width=700,height=500,toolbar=0,menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');return false;" style="background-position: -300px -120px" target="_blank"></a></li>
<li class="none nobackground"><a href="http://bit.ly/1VNpzTU" id="backforunical590" name="backforunical590" onclick="javascript:void window.open('http://bit.ly/1VNpzTU','1410949501326','width=700,height=500,toolbar=0,menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');return false;" style="background-position: -330px -120px" target="_blank"></a></li>
<li class="none nobackground"><a href="http://bit.ly/1qUAw8P%20Pi%20GPIO%20Inputs%20in%20Python" id="backforunical590" name="backforunical590" onclick="javascript:void window.open('http://bit.ly/1qUAw8P Pi GPIO Inputs in Python','1410949501326','width=700,height=500,toolbar=0,menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');return false;" style="background-position: -360px -120px" target="_blank"></a></li>
<li class="none nobackground"><a href="http://bit.ly/1VNpzTX" id="backforunical590" name="backforunical590" onclick="javascript:void window.open('http://bit.ly/1VNpzTX','1410949501326','width=700,height=500,toolbar=0,menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');return false;" style="background-position: -390px -120px" target="_blank"></a></li>
<li class="none nobackground"><a href="http://bit.ly/1WT6Rt2%20Pi%20GPIO%20Inputs%20in%20Python" id="backforunical590" name="backforunical590" onclick="javascript:void window.open('http://bit.ly/1UhB04O Pi GPIO Inputs in Python','1410949501326','width=700,height=500,toolbar=0,menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');return false;" style="background-position: -420px -120px" target="_blank"></a></li>
<li class="none nobackground"><a href="http://bit.ly/1qUAv4D%20Pi%20GPIO%20Inputs%20in%20Python&pic=&ralateUid=&" id="backforunical590" name="backforunical590" onclick="javascript:void window.open('http://bit.ly/1qUAv4D Pi GPIO Inputs in Python&pic=&ralateUid=&','1410949501326','width=700,height=500,toolbar=0,menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');return false;" style="background-position: -450px -120px" target="_blank"></a></li>
<li class="none nobackground"><a href="http://bit.ly/1WT6TRH%20Pi%20GPIO%20Inputs%20in%20Python" id="backforunical590" name="backforunical590" onclick="javascript:void window.open('http://bit.ly/1UhB30d Pi GPIO Inputs in Python','1410949501326','width=700,height=500,toolbar=0,menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');return false;" style="background-position: -480px -120px" target="_blank"></a></li>
<li class="none nobackground"><a href="http://bit.ly/1qUAwp8%20Pi%20GPIO%20Inputs%20in%20Python" id="backforunical590" name="backforunical590" onclick="javascript:void window.open('http://bit.ly/21fuaxu Pi GPIO Inputs in Python','1410949501326','width=700,height=500,toolbar=0,menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');return false;" style="background-position: -510px -120px" target="_blank"></a></li>
</ul>
<div class="clear"></div>
</div>
View more at: <a href="http://bit.ly/1XReQFr">http://bit.ly/1XReQFr</a>

Raspberry Pi GPIO Inputs in Python

1 Overview I left off having hopefully shown just how easy it is to get turn on an LED on the Raspberry Pi. First up I’m going to show a ...

Raspberry Pi GPIO Inputs in Python

Contact Form