Stuff for Gadgeteers and Makers

Blog Comments with Staticman

2018-06-08T00:00:00+00:00

Despite not being good at responding to all Comments on my WordPress Blog (I blame the fact that I could never get the email notifications to work from WordPress), I had some good Comments on a number of my posts that I didn’t want to loose. The Jekyll WordPress migration tool copied all the Comments into the front-matter of each post, so it was easy enough to render them under each blog post. But the real issue was how do you allow people to post Comments with a static site? Most of the big blog sites seem to have switched off Comments and instead rely on Social Media. I came up with various ideas involving Twitter and Amazon Lambda, and was about to abandon Comments entirely when I discovered a really elegant solution in a system call Staticman.

Staticman provides a couple of simple HTTP API endpoints that create Git Pull requests to add Comment files to your Git repository inside a Jekyll Collection. That’s a really elegant solution to the problem of Comments, all I have to do to approve a comment is merge the pull request to my Master branch. GitHub even sends me email notifications so I might even be better at responding to Comments in the future. Take a look at my Staticman config file if you want to see how I set it up.

Staticman is very flexible in how you want to organise your Comment collection but I still had the problem of my existing Comments. Rather than treat the old Comments different to any new Comments I wrote a small script in Ruby to create comment YAML files in my chosen collection from Jekyll front-matter. Look in the scripts folder of my sites Git repository if you want to see more.

I ❤️ Jekyll

2018-05-27T00:00:00+00:00

After a few years of neglect and paying Digital Ocean $5/month+tax for hosting by Wordpress site, I decided it was time for a change. I have been using the static website generator, Jekyll, at work to power a couple of websites and I just love it’s simplicity. Jekyll is also what powers GitHub Pages making it really simple to host really great looking blog totally for free on GitHub. There are plenty of examples of Jekyll sites and blogs hosted on GitHub Pages just a few clicks away on Google, but I thought I’d share some of the details of how I set up this site that I didn’t find elsewhere. Firstly, some of the things I love about Jekyll:

Markdown: It’s great being able to just type words and add simple formatting, but I’m still able to sprinkle in a few HTML tags if needed. I can even rely on my text editor (currently Atom) to check spelling as I type.
Git Workflow: Unlike my Wordpress site I can write content any where with just a simple text editor then push changes to a Git repository next time I’m online (I’m currently writing this 37,000 feet somewhere above the Indian Ocean). With GitHub Pages pushing to the Master branch of my repository automatically publishes the latest version of the site. Similarly, on my other Jekyll sites I have started using Git Hooks to invoke build and deploy scripts automatically when the Master Branch is pushed.
[Liquid]: Scripting in Liquid is good enough to create some pretty flexible layouts. See below for more about Liquid and Arrays.
Posts, Collections & Data: Jekyll’s built in ability to create pages and content from data files and YAML is really powerful.

The Challenges Moving my blog from Wordpress to Jekyll + GitHub Pages wasn’t all easy though, there were a few challenges I had to solve. Rather than describe them all here and make one long enormous post, I’ll create separate posts about each and include links here.

Blog Comments with Staticman

GitHub Pages and Jekyll plug-ins GitHub has a fixed, limited set of Jekyll plugins that it supports and will not execute any custom or 3rd party plug-ins. I assume they want to avoid people running custom code on their servers. I never felt the need to use Jekyll Plug-ins on the other Jekyll sites I have built so I didn’t think this would be much of an issues, but there was more than one occasion where a custom liquid filter (e.g. for processing a Jekyll data hash table) or Jekyll generator (e.g. for generating category pages) would have made things simpler. So far I have found work arounds but I keep wondering whether I will have to switch to generating my site elsewhere then pushing the generated site to GitHub. I really want to avoid that but we’ll see how it goes.

Soil Moisture Sensor with Arduino, XBee and Node-Red

2015-02-09T20:52:39+00:00

I have planted some chilli seeds and I am supposed to keep them moist, only trouble is I am rubbish at remembering to water my plants. I bought three cheap soil moisture sensor kits off ebay and hooked them up to an Arduino. The Arduino has an XBee shield and sends messages to my Raspberry Pi over a Zigbee network. The Pi is running Node-Red on node.js. When the soil moisture goes above a certain threshold it sends a message via Prowl to my iPhone.

Everything worked fine for three days then the sensors failed and I was continually receiving prowl alerts. Thank heavens for iOS "Do Not Disturb" otherwise I would have been woken up by constant alerts! It turns out that putting a continuos DC current through moist soil causes electrolysis on the soil moisture probes. One probe on each sensor had lost nearly all it's conductive coating. Apparently the only real solution to this problem is to use AC current, swapping polarity across the probes at regular intervals. I can't see how that is possible with my soil moisture kits so I have now redesigned things so that the sensors are only powered up for a second every 30 mins to take readings. According to my calculations the probes should last about 10 years this way - that should be long enough for my chillies to grow.

Assuming I can get this working, the next step will be to connect up 1 or 3 small water pumps to automate the watering. Although I think I might wait until the seedlings are big enough to put outside before I start spraying water all over the place in-doors.

Fibre Optic Broadband Availability Tools

2014-03-13T11:25:54+00:00

So what do you do if the BT's Broadband availability checker says that your exchange has been enabled for FTTC (Fibre to the cabinet), but your broadband provider says it is not available at your address? Dig a little deeper and look at whether you are connected directly to the exchange of via a cabinet.

Try these links:

BT Openreach When and Where: http://www.superfast-openreach.co.uk/where-and-when/

FTTC Checker : http://fttc-check.alc.im/results.php?postcode=SW1A2AA (change the post code to your own)

BT Broadband Availability Checker: http://www.dslchecker.bt.com/adsl/adslchecker.welcome

SamKnows Broadband Checker: https://www.samknows.com/broadband/broadband_checker

Only trouble is I still can't figure out how to find out when my local cabinet will be upgraded.

This looks like a useful troubleshooting tip.

With your modem/router unplugged, on your phone dial 17070, option 3, 1, 2, 2. What does it report back ?

Pretty as a Pi-cture: Raspberry Pi Server in a Picture Frame Case (phase 1)

2014-02-03T23:26:33+00:00

A couple of years ago I watched hak.5's Darren build a case for his gaming rig out of a couple of IKEA picture frames. Ever since then I have been waiting for the right opportunity to do the same. A couple of months ago the motherboard failed in My Mini-ITX server so I thought I'd try replacing it with a Raspberry Pi. The Pi has been performing it's home automation duties perfectly ever since but I couldn't find a decent Raspberry Pi server case. And so the inspiration for this project began.

I have a few USB peripherals hooked up to my Pi; an XBee coordinator attached to a XBee Explorer Dongle, an RFXCOM RFXtrx433 and a IOGear Bluetooth 4 dongle. The Pi is known to struggle to supply enough power for some USB devices so it made sense to use a powered USB hub, for which I chose a PiHub. I wanted all of this to go in the server case with the Pi.

The overall design is pretty simple. Mount the Pi, the USB hub and the USB devices in one picture frame without the glass. Then attach the second frame with hinges on top of the first without the backing panel. I also wanted to add sockets for power and Ethernet to the bottom edge so that they can be attached/detached easily from outside the case.

For phase 1 of this project I wanted to concentrate on getting everything mounted in the first frame.

Here's the parts list for my Pi-cture Frame case so far:

2 x IKEA RIBBA 500mmx500mm deep picture frames
SMA Male Plug Right Angle 10cm GSM GPRS 433MHz Antenna
Panel mount Ethernet extension cable
2.5mm Panel mount DC power socket
2.5mm Inline DC male plug
Short USB A to micro USB right angle cable
Short USB A to USB B cable
5 x M2.5x12 plastic nuts, bolts and washers
500mm-ish double strand cable

I spaced things out to leave me some flexibility to add other peripherals later. After all I still have one free USB port and all the Pi's GPIO pins left to play with.

The M2.5x12 nuts and bots fit the Raspberry Pi's mounting holes perfectly. All I had to do was to drill appropriate holes in the backing plate to bolt them together.

I used the same bolts with the PiHub but I had to dissemble it's casing to drill my own mounting holes. Two larger screwdriver sized holes in the backing board behind the casing screws make relatively easy to refit the hub's casing.

It was a similar situation with the RFXCOM but it's casing is stiffly snapped on. I decided it would be too hard to use the bolts so I just looped a couple of cable ties through holes in the casing and backing board. As the RFXCOM is effectively now mounted on its side, I also replaced it's original antenna with one that has a 90 degree mount. It's not officially supported by RFXCOM but so far I haven't noticed any degradation in performance.

The DC power socket was easy to fit by just drilling a suitable hole in the frame. The case was too thick to be able to use the socket's screw on retaining ring but it's a pretty tight fit without it. I soldered on some double strand cable and the inline male plug to the other end. This plugs directly into the PiHub. The 2.5mm socket is the same size as on the PiHub and it's power supply fits perfectly.

The Ethernet socket cable was actually the hardest thing to fit. It's basically square shaped and alI I have is round drills. It was that NASA "square plug in a round hole" problem. The end result is not as tidy as I would have liked but it's ok if you don't look too close underneath!

The whole thing in now hanging on my study wall, minus the glass front. The two antennas stick out a little too far to just use one frame. So in phase 2 I will add the glass fronted second frame onto the first frame with a set of hinges. To make it look nicer I will cover the backing board with something like dark felt. I'll also replace the long cable between the hub and RFXCOM with a shorter one. I am a little worried about ventilation so I might drill some extra large holes I the backing board which won't be visible from the front.

Improvised ReadyNAS NV Power Supply

2013-12-25T18:03:01+00:00

The power supply on my Infrant/Netgear ReadyNAS NV has died again. That's the third power supply in just over 7 years that has failed.

The ReadyNAS has mostly been great but the power supply really has been it's achilles heal. The RAID set up means that if a disk fails you can still get at your data and can simply swap out the failed disk for a new one. But when the power supply fails you are screwed. You can't get at your data and, since they use a proprietary wiring scheme, you can't just pop into you local PC store to buy a new one. Netgear will sell you a replacement, but they are really overpriced and it can take several days for shipping, assuming they even have them in stock.

Thanks to this ReadyNAS PSU pinout document I found on Netgear's ReadyNAS site, I figured out how to re-wire a standard ATX power supply to work with the ReadyNAS. I pulled a power supply out of an old PC and swapped a couple of wires around. The result isn't pretty but it works.

The hardest bit was actually pulling out the two molex pins without destroying the molex. This video came in very handy.
http://www.youtube.com/watch?v=kXMwCQ9fIVM&w=500

Howto fix a missing eth0 adapter after moving ubuntu server from one box to another

2013-12-12T20:00:34+00:00

The SATA controller on my Mini-ITX server's mother board has died. To get the important files off the drive I hooked it up to another PC and booted into Linux. It seemed to boot up perfectly (try doing that with Windows!), except the network adapter wouldn't start. After a bit of Googling around I found this article.

http://www.serenux.com/2009/11/howto-fix-a-missing-eth0-adapter-after-moving-ubuntu-server-from-one-box-to-another/

A Simple edit of a config file and reboot and we were back in business.

It seems that this is more a Debian thing than specific to Ubuntu. Same problem can occur on a Raspberry Pi and the same fix works.

Node-RED and XBee

2013-09-26T18:56:00+00:00

I recently discovered a really interesting new Open Source project for integrating devices and services, it's called Node-RED. Sponsored by IBM, the project is built on node.js and describes itself as "A visual tool for wiring the Internet of Things". It combines a graphical design tool that runs in a web browser and a runtime execution engine. Devices and services are represented by "nodes" which are wired together using the design tool to create a "flow". Although a number of built-in nodes are provided there isn't one for integrating an XBee wireless network so I rolled up my sleeves and built one.

My XBee "node" (there are definitely too many things called "node" in this project!) communicates with the XBee network through an XBee wireless module connected to the computer's serial port. It uses the excellent svd-xbee node.js module to communicate with an XBee module configured as a network Coordinator, using the XBee API mode. I use the Sparkfun XBee Explorer USB to connect the XBee module to my serial port. If you need information on how to configure XBee modules take a look at my earlier posts on XBee.

To use the XBee node in your own Node-RED flow, follow these steps:

Install node.js and Node-RED as per these instructions.
Install svd-xbee module. Currently the XBee node depends on the latest version of svd-xbee which is only available directly from GitHub.
$ npm install git+https://github.com/jouz/svd-xbee.git
Download or clone the XBee node from GitHub https://github.com/freakent/NR-XBee.git
$ git clone https://github.com/freakent/NR-XBee.git
Edit and run the XBee node's install script
Edit the install.sh script and change the NR_HOME variable to match the directory where you installed Node-RED. Make sure the script is executable and then run it.
$ chmod +x install.sh $ ./install.sh
Connect your Coordinator configured XBee module into a USB port and take note of the serial port your operating system associates it with.
On MacOS you can use
$ ls /dev/tty.usb*
Start up your Node-RED installation, as per the instructions here.
Hopefully Node-RED will start up and you shouldn't see any error messages relating to either the Serial or XBee nodes.
Check the XBee components are available in the Node-RED console
Fire up your web browser and point it at the URL given to you during Node-RED startup, typically http://127.0.0.1:1880/. The XBee node should be visible in the palette on the left as input and output nodes. You can now drag an XBee node into your flow and configure it as required.

Eventually Node-RED will support nodes being installed as regular npm modules so hopefully these instructions should get shorter in the future.

I now have everything I need to create v3 of my iDoorbell project, replacing Apache ServiceMix with Node-RED. Node-RED is looking like a much simpler and easier to use integration solution for me. Watch this space to see how it turns out.

Raspberry Pi Powered, Android Controlled, Tomcat Serviced, Remote Garage Door Opener

2013-06-28T13:22:56+00:00

http://ryanfx.blogspot.co.uk/2013/06/raspberry-pi-powered-android-controlled.html

http://pi4j.com/ The PI4J Project, Connecting Java to the Raspberry Pi

Teensy 3.0, like Arduino but better

2013-06-27T21:03:24+00:00

I've been looking for a low cost and smaller footprint Arduino board to use with XBee. Teensy 3.0 is now officially my favourite Arduino board.

I had high hopes for DigiSpark but it doesn't have a serial UART and I wasn't able to get the software serial library to work with it. The need to have 5V to 3.3V logic conversion didn't help either. Then I stumbled upon Teensy, a range of really small Arduino compatible boards. The latest model is the Teensy 3.0, powered by a 32bit ARM Cortex-M4 processor. Unlike most other Arduino boards, the Teensy 3.0 runs at 3.3V not 5V. This makes it much simpler to connect the Teensy 3.0 to an XBee which also runs at 3.3V. It has more analog and digital IO pins than a regular Arduino and THREE hardware serial ports. The USB connection can also be used to send additional Serial messages to the Arduio IDE serial monitor, very useful for debugging XBee serial communication without the debug messages interfering with the XBee communication.

Like the DigiSpark, the latest Teensy 3.0 was also a successful KickStarter project. The Teensy 3.0 is now available from PJRC's web site and other online electronics retailers. I ordered mine through Proto-Pic in the UK and it arrived less than 48 hours later.

It didn't take long to get the regular Arduino Blink program running on the Teensy. Soon after that I had the Teensy on a breadboard and wired up to an XBee on one of the Teensy's three serial ports. I'm really pleased with how painless it's been to get the Teensy 3.0 working. I will be ordering more for future projects.