Sunday, June 25, 2017

Kitesurfing 26th Jun 2017

Great wee session this afternoon down at Downhill. Wind was quite changeable, I tried both the 9 and the 12, but settled on the 9. Ended up doing two downwinders from the river to the mouth. Lovely flats between the waves, and nice ramps, up to 6-8 ft at the outside. Cross from the west side. Best day I've had for ages. The 9 is so nimble, makes me wonder if I should change the 12....

Wednesday, May 31, 2017

Connecting to a Raspberry Pi behind a 3G Router

Experimenting with 3G router and '3' free 200MB/Mth data SIM and of course there is the NAT problem, so I did this:

/usr/bin/sshpass -p "password" ssh -o ServerAliveInterval=60 -o ServerAliveCountMax=2 -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o ConnectTimeout=15 -N -R 22222:localhost:22 -p 1234

Then I can "ssh localhost -p 22222" on my local pi and get connected to the one behind the NAT. Excellent.

Saturday, April 01, 2017

Raspberry pi eGalax touchscreen calibration on zero / Raspberry pi 3 / PIXEL

Software updates bring compatibility problems, that's just how it is. Although the eGalax touch screen drivers are now in the kernel, and the touch screen functionality works out of the box, I couldn't get the touch calibrated.

Long story short, this is what I ended up with. Sometime xinput_calibrator came out with a section like this :

 Section "InputClass"
        Identifier      "calibration"
        MatchProduct    "eGalax Inc. USB TouchController"
        Option  "MinX"  "2881"
        Option  "MaxX"  "62736"
        Option  "MinY"  "60381"
        Option  "MaxY"  "5495"
        Option  "SwapXY"        "0" # unless it was already set to 1
        Option  "InvertX"       "0"  # unless it was already set
        Option  "InvertY"       "0"  # unless it was already set

but that was no good!

Then, finally, it came out with a section like this:
 Section "InputClass"
        Identifier      "calibration"
        MatchProduct    "eGalax Inc. USB TouchController"
        Option  "Calibration"   "103 1962 1864 158"
        Option  "SwapAxes"      "0"

with the "Option Calibration stuff on one line, and this seemed to work. I put it in /usr/share/X11/xorg.conf.d/99-calibration.conf

Hope that saves someone else the time :)

Wednesday, March 29, 2017

moving from inittab to systemd

For better or for worse raspbian has moved from the old System V init process control to the newer systemd version. I liked my inittab file, because it was quite simple and extremely easy to use, but it is no longer a choice.

So, I had this old line in inittab:
Gar:2345:respawn:start-stop-daemon --start -p /tmp/  -m --exec /usr/bin/java  -v -d /home/pi/builds -- -jar garageController.jar

And now I want to run it on a new Raspberry Pi.

So, we need to create a service, its actually quite simple. I created the file /etc/systemd/system/garage.service with this text:
Description=Garage Door Control Software

ExecStart=/usr/bin/java -jar garageDoor.jar gpio


Then we need to run a few commands to make sure our new service auto-starts.

sudo systemctl daemon-reload

sudo systemctl enable garage.service
sudo systemctl start garage.service

sudo systemctl --all | grep garage
##this should show that the service is started.

That's it. 

(I used instructions from

Monday, March 13, 2017

Raspberry pi wont update time on NTP

Weird problem with a pi zero-w, where when I put it on my friend's network it gets the wrong time.

Bit of a workaround, rather than a fix, but it got me up and running, and should be reliable...

  1. Open rc.local file
    sudo nano /etc/rc.local
  2. add following line to the rc.local file
    sudo date -s "$(wget -qSO- --max-redirect=0 2>&1 | grep Date: | cut -d' ' -f5-8)Z"
  3. reboot the Rpi
    sudo reboot
Basically, it gets the HTTP headers from the server at and sets the pi's time to that.


Monday, January 02, 2017

Using a Raspberry Pi to fix a broken Ethernet mains switch

Energenie LAN Switcher

My father-in-law uses an Energenie LAN switch to remotely manage the lighting in a shed where animals are kept. This means that the animals can be monitored remotely day and night by CCTV, and the lighting can be controlled either via the local web server on the LAN Switch, or via Energenie's internet web interface.

However, it stopped working. Time to call in the Raspberry Pi.

I already control my central heating using a Raspberry Pi and an off-the-shelf relay module, so I wondered if the exact same solution would work for the shed lights. I also wondered if I could shoehorn a Pi and the relay module into the energenie casing, so I opened it up.

Inside with the old electronics - you can see scorch marks from the old board failing

It looked like there was enough space there, so I removed the old control board with the burnt out components, and the next stage was to get the software and hardware working. I had an 8 channel relay board and an old Raspberry Pi lying around, so I decided to use those.

It is a while since I installed or updated Raspbian, so I downloaded the latest version, and I have to say, it seems that there is a lot more there by default now, which is helpful. I quickly got my heating server installed and configured, and connected the relay board, and it all worked easily.

The Pi with a relay module - I'm only using 4 relays

Using this I was able to connect via the PHP web interface, or via the android app I wrote for it. It's strangely satisfying to hear relays click on and off when you press buttons on your phone.

As this is really just a quick fix I wasn't going to change the app at all, so it still gets the title "heating controls" and the "on" command is "boost" like it is for the heating.

I set the boost to put the lights on for 6 hours, so that is effectively as long as would be required in one go. The heating controller backend has no concept of "on" or "off", only timed programs.

With this all working, it was time to box it all up. This was probably the trickiest part of the project, but I managed to get the relay module and Pi into the box. I had to do a bit of filing, but it turned out to fit quite snugly allowing the Ethernet connection out the end for easy access.

Relay board wired in

Everything fitting snugly

And some photos with the cover back on

The system has been in the shed for a few weeks now, and is working perfectly. The app allows connection over the local LAN or over the internet seamlessly, depending on which network is available, and the text based protocol means that with even with only GPRS or Edge the switching is very fast.