Saturday, October 18, 2014

Recent Updates to HESA

I've been spending time in small bursts recently working on the code for the Home Environmental Sensor Array.

Status Page Updated with Graphs
First of all, I updated the HESA status web page to display a graph of the current day's settings.  I found some php code called PHPGraphLib that makes it easy to create graphs with PHP.  In order to use PHPGraphLib, I made a new PHP page that reads today's readings from the database and puts them in an array variable.  Then, the data in the array is added to the class for the graph.  Finally, PHPGraphLib dynamically creates the graph as an image file on the server.  The main HESA status page calls the php page with the graphing code.  The PHPGraphLib page has some good documentation and was fairly easy to get going.

I also changed the HESA status web page to have a simple table with the high, low, average, and current readings for each sensor.  There are links to bring up the last 48 readings for each sensor.  In the future, I would like to make graphs for monthly and yearly data.

The final change I made to the Hesa status web page is to show at a glance if the HESA is working or not.  It checks the last time something was written to the database.  If the last update time is over an hour old, the title of the page changes.  Also, the status shows up at the top of the page.  Now, I can tell if the HESA is transmitting or not just by looking at the title of the web page.

Basic Design Failed.  Design Changed.  Backup Pump Added.  
Recently, I was replacing the sump pump in my basement.  While the pump was out, the water softener turned on and started dumping water into the crock.  When the crock filled up, the HESA detected the water and shut off power to the water softener -- exactly as designed.  What I found out, is that the water softener continues dumping water into the sink without electricity.  In other words, shutting off power to the water softener does nothing.  Yar!

In order to fix this design problem, I did a couple of things.  First, I bought a submersible pump and battery powered sump pump but I would prefer to have a battery backup solution for the whole system.

added it to the crock.  The submersible pump will move water from the crock for the basement sink to the crock for the drain tiles.  The sump pump in the second crock will then move the water outside.  This will help when the first sump pump fails for some reason.  I still have a problem when the power in the basement fails.  Yes, I could have a

Finally, I changed the programming on the HESA so the Power Switch Tail is normally off.  When the HESA detects water, it sends a signal to the PST to turn it on and provide power to the submersible pump.  This is the opposite of the way the HESA provided power to the PST originally but it fixes the design flaw.

Send All Clear Message
One small improvement I made is to send an "all clear" message to the email address if the water goes away.  Now, when I am doing some testing, people will get a follow-up email when all is well.

HESA Not Transmitting
I have been having problems with the HESA not transmitting.

First, There were some bugs in the code that would stop the program if it could not reach the internet.  I fixed those.

Next, the GFCI outlet that my network hub was plugged in to would trip on occasion.  The HESA would stay running but it could not send any data to the internet.  I had to fix this because the sump pump was also plugged into the same power outlet.

That GFCI outlet has a freezer plugged in to it, plus the sump pump, and a power strip with my network hub and a small clock.  For some reason, the outlet would trip when the sump pump tried to run sometimes.  Perhaps it was when the freezer motor was also kicking on.  I solved this problem by adding a bigger outlet and a second GFCI outlet.  Now, the freezer has its own 20 amp GFCI outlet.  The sump pump and power strip share the other 20 amp GFCI outlet.  I have not had any more problems with the GFCI outlets tripping since I made this change.

Even after these changes, once or twice a week, the HESA still stops transmitting.  When I check the processes that are running, there is no HESA program.  It appears that some kind of run-time bug causes the program to stop.  I need to start recording everything that happens in a log file so I can see where it stops.  Then, I can fix the code to handle the errors.

Until then, I made a change the /etc/rc.local file to hopefully restart the program if it fails.  Here is the code.

until sudo python /home/pi/python/; do                
    echo "HESA crashed with exit code $?.  Respawning.." >&2 
    sleep 1                                                  

The HESA rebooted and started just fine.  We'll see if this change to the rc.local file fixes the HESA from stopping or not.

Friday, October 3, 2014

Power Connector for Chromebook Fixed

After about nine months of use, the power supply for our HP Chromebook stopped charging.  It looked like some wiring broke close to the end of the connector.  Too much flexing where the cable plugs in to the computer finally caused the wire to break.  What to do?

Best Buy sells a universal charger for $55.  That's bit steep.

Fortunately, I am a member at the Milwaukee Makerspace.  A few Fridays ago, I took the broken PSU to the 'space in hopes of saving myself $55.

My first idea was to find a power supply with a similar end.  I looked through the power supplies on the hack rack at the Makerspace.  There were plenty of old PSUs on the rack but none were an exact match.

Option two was to fix the connector on the current PSU.

To start, I cut away the plastic covering on the connector to reveal the wires.  Curiously, there are three conductors in the cable -- one white, one black, and one blue.  The white wire is hot.  The black wire is the return.  No idea what the blue wire is for.  I probably would need to break open the power supply brick to see what the blue wire is connected to.

The white and black wires were a bit frayed.  This was the problem.  I cut through the wires to separate the connector from the PSU.  Next, I used a Dremel tool to grind away the hard plastic that covered the connections on the connector.

Finally, I soldered the wires to the connect.  Heat shrink tubing was used to cover the wires.  The hole thing was also wrapped with electrical tape.

A quick test showed that the repair was good.  It has been charging the Chromebook for the last few weeks.

It felt good to fix the PSU.  Plus, saving $55 pays for one month at the Makerspace.  Bonus!

Friday, September 5, 2014

phpMyAdmin Works on HESA

I spent Labor Day weekend working on the Home Environmental Sensor Array on my Raspberry Pi.  I want to start reading and writing data on MySQL tables on the Raspberry Pi.  In order to make this easier, I need to use phpMyAdmin on my laptop to manage the MySQL databases on the Raspberry Pi.  There were several things I had to do to get this working.

First, phpMyAdmin tries to only connect to the MySQL server on the localhost.  I found a web page that explained how to get phpMyAdmin to connect to MySQL on another device.  Basically, I had to edit the file in the /etc/phpmyadmin folder.  The lines below were added after the section like it that setup the localhost connection.
$cfg['Servers'][$i]['verbose']         = 'HESA';$cfg['Servers'][$i]['host']            = 'hesa.local';$cfg['Servers'][$i]['port']            = '3306';$cfg['Servers'][$i]['connect_type']    = 'tcp';$cfg['Servers'][$i]['extension']       = 'mysqli';$cfg['Servers'][$i]['compress']        = FALSE;$cfg['Servers'][$i]['auth_type']       = 'cookie';$i++;
One thing to note is that these lines can be added to this file for every server that you want to control with this copy of phpMyAdmin.

Next, I had to go to the Raspberry Pi and tell MySQL to allow connections on the public internet connection and port 3306.  This is done by editing the /etc/mysql/my.cnf file and changing the bind-address variable in the [mysql] section to the local IP.  In my case, it looked like this:
bind-address =
Finally, I had to setup security for the users in MySQL.  I started up the mysql command line tool and executed a command like this:
Now that I am documenting all of this, it seems pretty simple. Its hard to believe that I spent so much time trying to get this to work.  Here is the end result.  Now, there is a Server Choice dropdown that shows all the servers, I can connect to from my laptop.

After getting this working, I created tables for the data that I store on the website.  I also mostly copied data from the production site to the database on the Raspberry Pi.  The RJ comments table did not fully copy.  There is probably something wrong with the variable size for the id column.  I'll deal with that later.

Tried Soldering the USB Connector to the PCDuino

I did not post this right away but about two weeks ago, I attempted to re-attach the USB port to the pcDuino that I am working on.  The USB port got disconnected soon after I started working with the pcDuino.  The design of the board is such that a USB cable does not fit correctly when an HDMI cable is plugged in.  The first picture below shows the USB port separated from the board.

The picture below is me trying to solder the USB port back onto the board.  I used a microscope at the Milwaukee Makerspace to see the work since the connections were so small.  I tried to take my time to do it right.  The USB port was solidly connected to the board when I was done and it looked like a decent job but the board still does not power up when I plug a USB cable into it.

Friday, August 8, 2014

Motorshield Assembled for pcDuino v2

Today, I continued working on the Wifi Enabled, Remote Controlled, pcDuino Powered, Video Surveillance Robot.  I bought a MotorShield v2.3 from Adafruit.  It came mostly assembled for some reason.  I simply had to solder on the connector pins.  That was pretty easy.  (See the pictures below.)

The next step is to test an Arduino script to run a motor.  The problem is that I need to run a GUI interface on the pcDuino.  This means that I need to have both a keyboard and mouse plugged in to the one USB port on the pcDuino at the same time.  I do not have a USB hub and I could not find one at the Makerspace.  I thought about making one but it looks like I would have to make my own PCB.  Probably not worth it.

So, I will have to put off testing the motor shield until I get a USB hub.  In the meantime, I downloaded the Arduino script files for the board from Adafruit.  The files were in a zip format, that I downloaded to my laptop.

In order to get the zip file to the pcDuino, I installed FTP server on the pcDuino by executing sudo apt-get install vsftpd.  Then, I used FileZilla to move the zip file to the pcDuino.

Whenever I get a USB hub, I will be ready to test the motor.

Unassembled motor shield.

Bottom view of shield with pins soldered on.

Top view of shield with pins soldered on.

The shield attached to the pcDuinoV2.

Saturday, August 2, 2014

HESA Now Recording Temperature and Humidity

After getting the HESA to write data to a SQL database, I feel like I need to measure more things.  This week, my new DHT 22 temperature and humidity sensor arrived from Adafruit.  I spent a few hours Home Environmental Sensor Array.
this morning hooking it in to the

Adafruit makes it super-easy to use the DHT22.  They have their own code library for Python.  There are a few steps to get the code installed.  Full instructions are here.

The first step is to download the code from github to the modules folder on the pi.
git clone
The next step is to update the python development library.  Mine was up-to-date so I did not need this.

The final step is to install the DHT code library into python so it can be loaded as an include.  The Adafruit code from github comes with a program that does this automatically.  All I needed to do was cd into the correct folder and type
sudo python install
Next, I wired the DHT 22 into my Raspberry Pi.  It has four pins but only uses three.  Pin one goes to power.  Pin two connects to a GPIO pin to read the settings.  I used GPIO 7 or physical pin 4 on the Pi.  Pin two also connects to power through a resistor.  Pin four connects to ground.

The code to read the temperature and humidity is simple:
humidity, tempC = Adafruit_DHT.read_retry(sensor, dhtPin)
 The sensor variable tells the function what model sensor we are using.  In this case, sensor = 22.  The dhtPin variable tells the function which physical pin on the Pi pin 2 on the DHT is connected to.

The function sends back the humidity and temperature.  The temperature is in Celsius.  I convert it to Fahrenheit with this formula:
if tempC is not None : tempF = '{0:0.1f}'.format(1.8 * tempC + 32)
This formula also formats the temperature to have only one decimal point.

The code for the HESA now sends temperature and humidity readings to my SQL server database once an hour.  I also changed the code so it updates my local web page once every ten minutes and updates the database once every sixty minutes.  Before this, it was simply counting cycles and estimating the times for updating.

The link to view the data on the webpage is here.

Saturday, July 26, 2014

Setting up the pcDuinoV2 -- Wireless and xWindows

I spent some more time working on the basic setup of the pcDuinoV2 that Pete from the Milwaukee Makerspace asked me to play with.

First of all, the board was booting up into xWindows on startup.  I thought I disabled that feature using the configuration program that is in the OS but apparantly not.  I managed to get xWindows to stop loading by creating a file named lightdm.override in the /etc/init folder.  The only line it had was one word: 'manual'.  

Now, the device boots to a text-based screen but the resolution looks like it is 1024x768.  In order to fix that, I had to run the configuration program from the command line by typing 
 and then setting the screen resolution back to 1152x864-75.  Rebooted.   The screen still came up in the lower resolution.  Maybe there is a permanent fix for this but I don't have time to research it.  It is pretty easy to set the screen resolution after bootup.

Next, I worked on the wireless network card.  There are some pretty good instructions about enabling a wireless NIC in Ubuntu at this website:

First, I created a file named wpa_supplicant.conf in the /etc folder.  It had these lines in it:
network={    ssid="MilwaukeeMaker"    psk="secretPassword"}

Next, I put these commands in /etc/network/interfaces

auto wlan3iface wlan3 inet dhcp    pre-up wpa_supplicant -B -Dwext -i wlan3 -c /etc/wpa_supplicant.conf    post-down killall -q wpa_supplicant

That's it.  The initial setup of the pcDuino is done.  
  • it boots to the command line
  • can connect to it at pcDuinoV2.local on any network because of Avahi
  • all upgrades are done (updates still don't seem to work)
  • wireless networking works
The next phase in this project is to build the robot base and control it with the
pcDuino.  In order to keep things moving, I ordered a Motor/Stepper/Servo Shield for Arduino v2 Kit from Adafruit.  

Since the pcDuino has Arduino compatible pins on it, shields made for the Arduino will work with the pcDuino.  I can use the motor shield to learn how to control motors with the pcDuino.  That should take a few weeks.  In the meantime, I will try to find parts for the base.  I'd like to find or make as many parts as possible at the Makerspace.  

Finally, I think I would like to make a robot that looks like Wall-E.  This means, I will need treads instead of wheels.  I did a bit of research into treads and they are not cheap.  Maybe I can 3D print something.