• Fix orphan image attachments in wordpress/woocommerce

    November 18, 2015 Author: RobinC
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    I ended up with a load of orphan image attachments. By which i mean the post_parent of the image attachment was 0. This is bad in one particular situation. Although all the images were in use on posts, Google has a habit of indexing the attachment pages as well and often these are not themed and do not contain the info you want end users to see, For example http://example.org/product/attachment/1234/. Its possible to use plugins to add no-index no-follow meta tags to the attachment pages that will remove them from search. But this seemed a bit half-arsed. Plugins such as Yoast SEO have options to redirect attachment pages back to the parent post. But this is useless if the post_parent is 0.

    So i came up with the following quick hack to run on the server from a ssh prompt.

    
<?php 
$sapi_type = php_sapi_name(); 
if (substr($sapi_type, 0, 3) == 'cgi') 
{ die("You are using CGI PHP\n"); } 

require('wp-blog-header.php'); 
require ( ABSPATH . 'wp-admin/includes/image.php' ); 

$args = array( 'posts_per_page' => 1000,
        'offset'           => 0,
        'category'         => '',
        'category_name'    => '',
        'orderby'          => 'date',
        'order'            => 'DESC',
        'include'          => '',
        'exclude'          => '',
        'meta_key'         => '',
        'meta_value'       => '',
        'post_type'        => 'product',
        'post_mime_type'   => '',
        'post_parent'      => '',
        'author'           => '',
        'post_status'      => 'publish',
        'suppress_filters' => true
);

$posts = get_posts($args);


foreach ($posts as $post) {
   // Get post title
   $post_thumbnail_id = get_post_thumbnail_id( $post->ID );
   $parentid = wp_get_post_parent_id( $post_thumbnail_id );
   if($parentid == 0)
   {
        wp_update_post(
                array(
                        'ID' =>  $post_thumbnail_id,
                        'post_parent' =>  $post->ID
                )
        );
   }

}

?>

    This script finds each post of post_type, gets the featured image ID, then looks up this to see if the post_parent is 0. If it is 0 it sets the post_parent of the image to the post ID determined before. The first few lines ensure that this script is only executable from the command line/ssh prompt so that if you leave this on your web-server it cannot be executed by the http process. However i would encourage removing it directly after use.

    The things to note with this are:-

    1. This will run on the first 1000 posts, if you need more, probably best to create an outer loop and use that offset parameter
    2. post_type is set to “product” this is good for woocommerce product posts, for regular posts make this “post”

  • CanOpen on a Raspberry PI using CanFestival

    November 12, 2015 Author: RobinC
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    I wanted to hook a Raspberry PI into a CanOpen network and have it as a slave device, mainly for logging purposes. I had previously identified CanFestival  as a potential CanOpen stack to be used for this project as it describes itsself as “CanFestival focuses on providing an ANSI-C platform independent CANOpen® stack that can be built as master or slave nodes on PCs, Real-time IPCs, and Microcontrollers” so that is sounding promising.

    The other potential stack I had considered was CanOpenNode, this stack wins hands down for implementing on a PIC32/24 as it pretty much works out of the box on those platforms. The devil is always in the details and in this case the detail is the driver, or how the stack connects to the actual can hardware. Both stacks have certain “drivers” that allow them to interface to the host, both stacks as C implementations that just seem to work. But the winner was CanFestival supported socket_can.

    Socket_can is an implementation of can using unix sockets, this might not seem like a big deal, but its very efficient. Sockets have built in queuing mechanisms and expose them selves to usespace in a nice friendly way. Through put is not going to be an issue. Other CAN systems use character devices, eg they emulate a serial port and you talk one byte at a time to the character device. This is inefficient and has no queuing, so on busy networks things could go wrong.

    The hardware selected was the PICAN board from SK Pang (UK Supplier). Quick delivery, the board arrived next day and I was excited to start playing with it. I am using a Raspberry PI 2 and there are slight differences between the 1 and 2 when setting up the drivers on the PI (hint PI2 is much improved)

    Can board on raspberry pi 2

    Complete instructions can be found on SK Pang’s blog but the TLDR; version is in raspi-config, advanced -> turn on SPI. then add to /boot/config.txt the following

    dtoverlay=mcp2515-can0-overlay,oscillator=16000000,interrupt=25
dtoverlay=spi-bcm2835-overlay

    Thats it, a reboot later everything should be good the correct kernel modules will load at boot and the can interface will be ready to go.

    CanFestival

    The purpose of this was CanOpen not just raw can so lets proceed with Festival, we will do this on the raspberry PI as it should be ready to go with code compiling and will save the hassle of a cross compile setup for such a trivial thing.

    Download the source code from http://dev.automforge.net/CanFestival-3/ , you can check out the code as a Mecurial repository, or if you don’t know what that is, just download the latest source from http://dev.automforge.net/CanFestival-3/archive/tip.tar.bz2 which will get the latest code as a tar ball with bz2 compression.

    wget http://dev.automforge.net/CanFestival-3/archive/tip.tar.bz2
    Unpack the code
    tar -xvjf tip.tar.bz2
    Change directory to move into the source tree, Note at the time of writing the tip ID was 8bfe0ac00cdb when you do this it may have changed so just cd into the folder just unpacked which will be named CanFestival-3-?????????????
    cd CanFestival-3-8bfe0ac00cdb
    Now configure and build the code
    ./configure --arch=armv6 --target=unix --can=socket
    make
    sudo make install

    So thats good to go at this point and you should be able to test, an annoying niggle is that the can interface needs to be brought up with the “link” command, i am sure this can be fixed in festival but as it stands out of the box to run the first thing you need to do is :-

    sudo /sbin/ip link set can0 up type can bitrate 500000
    CanOpenShell load#libcanfestival_can_socket.so,can0,500k,1,1
    Where the paramaters for load are library name, can channel, bitrate, nodeID and master(1)/slave(0)

    If CanOpenShell starts correctly you should see

     Node_initialisation
Note_preOperational

    at this point press enter

    You can then sent NMT commands with the ssta/ssto/srst/scan commands eg ssta#0 start all nodes, and you can read and write SDOs with the rsdo and wsdo commands
    so you can talk to other CanOpen devices and prove you have a working network.

    Creating a node with festival

    So how do you actually use festival to do something real? The best example to start with and the simplest is in examples/SillySlave and is a very basic demo of a CanOpen slave on the network. Of cause sillyslave didn’t compile out of the box with the rest of festival and to get it to work do the following, firsty move to the /examples/sillyslave directory and edit the Makefile( eg use nano Makefile -c) on line 42 go to the very end and remove “-lcanlib”

    Next you also need to edit main.h and change the following defines in the section marked “Please tune the following defines to suit your needs:”

    #define NODE_MASTER 0x1
    #define NODE_SLAVE 0x40
    #define DRIVER_LIBRARY "libcanfestival_can_socket.so"
    #define BAUDRATE 500
    #define BUS 0

    Next you need to build as follows :-
    make mrproper
    make

    This is important as the SillySlave.c file is out of date and old and needs to be regenerated, only the mrproper target will remove it, not just make make all or clean. What it actually does is generate SillySlave.c from an XML representation of the object dictionay and using another tool this can be converted to/from the EDS/electronic data sheet files that is part of the CanOpen standard.

    To run the sample just do :-

    ./SillySlave

    If you have another can node, you can start/stop the node with NMT commands, and it will send a PDO for every SYNC it receives.

    The important thing to take home here is main.c is trivial, its the minimum needed to start up the application, SillySlave.c is machine generated and this is the goodness of the object dictionary and how you configure the main parts of your node.

    Creating an object dictionary with festival

    So the time has come to make the Sillyslave something real, your friend in this process is the objdicteditor tool, which is a python tool

    You need to run this from a GUI, either the PI’s X windows or another system (even windows) with python and python wx installed. Lets assume you are using the PI still. Firstly ensure you have the wx widgets for python
    sudo apt-get install python-wxtools
    Then change to X windows and use a keyboard and mouse to continue
    Open a terminal window and CD to the directory containing the canfestival source, then cd into the objdictgen directory and do the following python objdictedit.py Then if you go to File->Open abd browse to the examples/SillySlave directory and open SillySlave.od you can edit the object dictionary from a nice GUI with ease, any changes you make if you save them back to the od file you can then build this into the slave by following the previous steps to build sillyslave with your new changes.

    Canfestival object dictionary editor

    A few finishing words

    Sillyslave is very basic, the bare minimum and really the defines for the nodeid and the bitrate are wrong and these should be read from the object dictionary directly. If you need to add more advanced functionality CanFestival has callback hooks which can be used, but i leave developing a real application as an exercise for you to do on your own as this is where the business end of what ever you are trying to do actually starts now all the boiler plate is taken care of.

  • Ustream videos from the command line on a RaspberryPi

    November 9, 2015 Author: RobinC
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    As i’ve just got my hands on a 7″ offical Raspberry PI display and a PI 2.0 i was playing around and thought what is the easiest way to get some interesting video on the screen. So i though as a test i would use the live ISS HD feed from NASA as that is on Ustream and is a pretty cool thing to have on.

    After some quick research omxplayer was the way to do this. And http://blog.miguelgrinberg.com/post/watch-live-video-of-earth-on-your-raspberry-pi did exactly what i needed

    So I installed omxviewer, python-pip and livestreamer (using python-pip) and the basic command is livestreamer http://ustream.tv/channel/iss-hdev-payload mobile_480p --player omxplayer --fifo

    I changed it to

    livestreamer http://ustream.tv/channel/iss-hdev-payload mobile_480p --player omxplayer --fifo --player-args "--blank {filename}" to ensure it blanked the unused parts of the screen.

     

    NASA ISS HD feed running on omxplayer on a Raspberry Pi

    NASA ISS HD feed running on omxplayer on a Raspberry Pi

    Lots of playing to be done, but for the moment on with some serious work…

  • CanOpen

    November 6, 2015 Author: RobinC
    No comment yet

    I’m currently using CanOpen a lot and although there are loads of good documents they are scattered around the internet but no one site I find has everything i need. So this represents my own personal notes on CanOpen that I hope if of benefit to others. I cannot guarantee everything is accurate and if you find a mistake please let me know so i can correct it.

    The start of my documentation can be found here

  • Quick and dirty wordpress to twitter feed with images

    September 6, 2015 Author: RobinC
    1 Comment

    I wanted a really quick and dirty implementation of a wordpress blog post to twitter feed and came up with the following. i didn’t even bother to implement this as a plugin (although you could quite easily and this is really where it belongs). But just as a proof of concept i added the code to the functions.php file in my theme

    The basic principle is to hook the new post event which is
    add_action( 'publish_post', 'post_published_notification', 10, 2 );

    This is fired every time a post is published so you can then feed the data on to twitter. I also wanted to send embedded images to twitter, so i used the posts thumbnail as the image source. For the engine to actually speak to twitter i used codebird.

    I’ve broken it down into 3 functions the first one is substrwords() which is a helper function that takes a string and ensures it is no longer than $maxchars but terminates on a word boundry.
    Next we have twitterpost() this does the actual post to twitter. Ensure you set your twitter API keys and secrets for this to work. The final function is the post_published_notification() function. This is what gets fired from the action callback. It gets the post and finds the attached image. Really it should check that an image is attached and not blindly assume that it is. But i will leave this as an exercise for the reader to implement.

    The actual implementation looks something like :-

    require_once('codebird.php'); < /code>

function substrwords($text, $maxchar) {
    $end = '...';
    if (strlen($text) > $maxchar || $text == '') {
        $words = preg_split('/\s/', $text);
        $output = '';
        $i = 0;
        while (1) {
            $length = strlen($output) + strlen($words[$i]);
            if ($length > $maxchar) {
                break;
            } else {
                $output. = " ".$words[$i];
                ++$i;
            }
        }
        $output. = $end;
    } else {
        $output = $text;
    }
    return $output;
}

function twitterpost($url, $posttxt, $imglink) {

    $consumerKey = "";
    $consumerSecret = "";
    $accessToken = "";
    $accessTokenSecret = "";

    $posttxt = $url." ".substrwords($posttxt, 114);

    \Codebird\ Codebird::setConsumerKey($consumerKey, $consumerSecret);
    $cb = \Codebird\ Codebird::getInstance();
    $cb->setToken($accessToken, $accessTokenSecret);

    $params = array(
        'status' => $posttxt,
        'media[]' => $imglink
    );
    $reply = $cb->statuses_updateWithMedia($params);
}

function post_published_notification($ID, $post) {
    $type = get_post_type($post);

    if ($type != "post") {
        return;
    }

    $title = $post->post_title;
    $permalink = get_permalink($ID);
    $image = wp_get_attachment_image_src(get_post_thumbnail_id($post->ID));
    $imgurl = $image[0];

    twitterpost($permalink, $title, $imgurl);
}
add_action('publish_post', 'post_published_notification', 10, 2);

  • Add facebook posts to wordpress blog?

    April 17, 2015 Author: RobinC
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    I could not find any Facebook feed readers I was happy with. There are loads of plugins that provide sort of what I wanted, Facebook content could be displayed on a specific page using tags. Or you could use a rss feed reader and try and parse the Facebook rss for a page. This was not that easy and ended up with small images and incomplete sets of images.

    The only real way to get Facebook data is via Graph API

    So i wrote a WordPress plugin and its is here

    https://github.com/robincornelius/facebookpagewpfeeder

  • lirc sky rflink howto

    April 23, 2014 Author: RobinC
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    NB This Howto is around 5 years old, but its still linked to from some sources so I though I would keep it alive, the lirc bits are probably a little out of date by now

    This howto is a quick description of how i got a pace rflink device (designed for TIVO) working on a standard RS232 serial port with lircd

    Pace rf2link

    The rf2link is a remote control extender for SKY and SKY+ systems that sends the control commands via the coax cable that is also used to send the picture to other televisions. These can be bought from http://www.pacelink.co.uk/rf2link.htm. These devices run of 9v power from the SKY/SKY+ box that can be switched on from the RF2 socket. Two varieties exist one of which allows the power to continue to the NEXT device along the coax and one that stops the power at the rf2link device, ONLY use the through power device IF you require the power at the next device, i.e. another remote extender. DO NOT ALLOW the 9v to reach your TV or your capture card! You have been warned!.

    These are designed for a TIVO so two possibilities exist :-

    1 – Cut off the jack plug
    2 – Make a nice socket for the jack plug to plug in to

    I chose number one. Next you will need some 1N4148 diodes or similar small signal diodes, a female DB9 socket and a plastic cover to mount the DB9 socket and hide away the 1N4148 diodes. These parts can be obtained from maplins http://www.maplin.co.uk or you local electronics shop.

    Serial ports can signal from -9v to +9v (nominal) and can have voltages much lower than this. I assumed my serial port was 9v and used 4 diodes (0.6-0.7v drop per diode) and to stop the serial port putting any -ve voltages on the pacelink device.

    DTR. -------->|---->|---->|----->|------- PACELINK Centre of cable

GND ---------------------------------------- PACELINK Ground of cable

    The pace link device input drives into a 3.5k ish resistor so i suspect a few extra volts won’t hurt but their are a load of transistors next so i would not recommend any negative volts reaching them so a minimum of one diode always!.-

    [Read More…]

  • RS232 TTL to USB

    April 23, 2014 Author: RobinC
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    I’m often hacking around with some device that has RS232 but at TTL levels and I quickly want to connect it to a PC for some testing or set-up, but I came across these wonderful devices ready to go out the box :-

    TTL RS232 to USB convertors

    TTL RS232 to USB convertors

    Available from RS Components http://uk.rs-online.com/web/p/interface-development-kits/6877770/ there are 5V and 3.3V TTL versions available. They are not the cheapest things in the world but they are ready to go directly into your TTL RS232 level device and come on a standard 0.1″ pitch connector that also provides +5V if needed.

     

     

  • Ban hammer, fail2ban geo ip on google maps

    April 21, 2014 Author: RobinC
    10 Comments

    Though it would be fun to display the banned IP addressed on the server from fail2ban using google maps and geo ip, a quick google revealed this was already done so my solution is based on two following code bases for inspiration:-

    https://github.com/martzuk/fail2ban-geo/

    http://www.dbsysnet.com/howto-geolocation-for-fail2ban/

    I started off with the dbsysnet code but modifed this to use google maps V3 API, then i stole the nice UI and map images and other stats ideas from fail2ban-geo, then rewrote the data fetcher to use JSON and ended up with the current version.

    The current live version is at

    http://static.byteme.org.uk/banhammer/

    [Read More…]

  • A z80 assembler in C# with IDE

    February 7, 2014 Author: RobinC
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    Having a number of legacy z80 projects that still need supporting it was about time I wrote a modern z80 assembler and IDE to manage this problem.

    We had been using AD2500’s z80 assembler which was all fine, but only 16 bit, no ide no other fancy features. But of its day it seemed like a pretty rock solid assembler. I can’t really be bothered to install XP in a VM just to run the old 16 bit apps. So i’ve started a new project to create a modern C# based IDE and assembler to help out those that still need this stuff or those who just want to learn some assembler for education. z80 is a nice place to start with assembler to learn some basics before diving in to more complex processors.

    Below is an image of the work so far :-

    z80ide

    The code can be found at

    https://github.com/robincornelius/z80assembler

     

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