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Noodles' Emptiness



Dude! Sweet!



Published: Sat, 14 Jan 2017 11:58:53 +0000

Last Build Date: Sat, 14 Jan 2017 11:58:53 +0000

 



Cloning a USB LED device

Sat, 14 Jan 2017 11:53:56 +0000

A month or so ago I got involved in a discussion on IRC about notification methods for a headless NAS. One of the options considered was some sort of USB attached LED. DealExtreme had a cheap “Webmail notifier”, which was already supported by mainline kernels as a “Riso Kagaku” device but it had been sold out for some time.

This seemed like a fun problem to solve with a tinyAVR and V-USB. I had my USB relay board so I figured I could use that to at least get some code to the point that the kernel detected it as the right device, and the relay output could be configured as one of the colours to ensure it was being driven in roughly the right manner. The lack of a full lsusb dump (at least when I started out) made things a bit harder, plus the fact that the Riso uses an output report unlike the relay code, which uses a control message. However I had the kernel source for the driver and with a little bit of experimentation had something which would cause the driver to be loaded and the appropriate files in /sys/class/leds/ to be created. The relay was then successfully activated when the red LED was supposed to be on.

hid-led 0003:1294:1320.0001: hidraw0: USB HID v1.01 Device [MAIL  MAIL ] on usb-0000:00:14.0-6.2/input0
hid-led 0003:1294:1320.0001: Riso Kagaku Webmail Notifier initialized

I subsequently ordered some Digispark clones and modified the code to reflect the pins there (my relay board used pins 1+2 for USB, the Digispark uses pins 3+4). I then soldered a tricolour LED to the board, plugged it in and had a clone of the Riso Kaguku device for about £1.50 in parts (no doubt much cheaper in bulk). Very chuffed.

In case it’s useful to someone, the code is released under GPLv3+ and is available at https://the.earth.li/gitweb/?p=riso-kagaku-clone.git;a=summary or on GitHub at https://github.com/u1f35c/riso-kagaku-clone. I’m seeing occasional issues on an older Dell machine that only does USB2 with enumeration, but it generally is fine once it gets over that.

(FWIW, Jon, who started the original discussion, ended up with a BlinkStick Nano which is a neater device with 2 LEDs but still based on an Tiny85.)




2016 in 50 Words

Fri, 06 Jan 2017 08:03:37 +0000

Idea via Roger. Roughly chronological order. Some things were obvious inclusions but it was interesting to go back and look at the year to get to the full 50 words.

Speaking at BelFOSS. Earthlings birthday. ATtiny hacking. Speaking at ISCTSJ. Dublin Anomaly. Co-habiting. DebConf. Peak Lion. Laura’s wedding. Christmas + picnic. Engagement. Car accident. Car write off. Tennent’s Vital. Dissertation. OMGWTFBBQ. BSides. New job. Rachel’s wedding. Digital Privacy talk. Graduation. All The Christmas Dinners. IMDB Top 250. Shay leaving drinks.

(This also serves as a test to see if I’ve correctly updated Planet Debian to use https and my new Hackergotchi that at least looks a bit more like I currently do.)




IMDB Top 250: Complete. Sort of.

Sat, 31 Dec 2016 16:01:13 +0000

Back in 2010, inspired by Juliet, I set about doing 101 things in 1001 days. I had various levels of success, but one of the things I did complete was the aim of watching half of the IMDB Top 250. I didn’t stop at that point, but continued to work through it at a much slower pace until I realised that through the Queen’s library I had access to quite a few DVDs of things I was missing, and that it was perfectly possible to complete the list by the end of 2016. So I did. I should point out that I didn’t set out to watch the list because I’m some massive film buff. It was more a mixture of watching things that I wouldn’t otherwise choose to, and also watching things I knew were providing cultural underpinnings to films I had already watched and enjoyed. That said, people have asked for some sort of write up when I was done. So here are some random observations, which are almost certainly not what they were looking for. My favourite film is not in the Top 250 First question anyone asks is “What’s your favourite film?”. That depends a lot on what I’m in the mood for really, but fairly consistently my answer is The Hunt for Red October. This has never been in the Top 250 that I’ve noticed. Which either says a lot about my taste in films, or the Top 250, or both. Das Boot was in the list and I would highly recommend it (but then I like all submarine movies it seems). The Shawshank Redemption is overrated I can’t recall a time when The Shawshank Redemption was not top of the list. It’s a good film, and I’ve watched it many times, but I don’t think it’s good enough to justify its seemingly unbroken run. I don’t have a suggestion for a replacement, however. The list is constantly changing I say I’ve completed the Top 250, but that’s working from a snapshot I took back in 2010. Today the site is telling me I’ve watched 215 of the current list. Last night it was 214 and I haven’t watched anything in between. Some of those are films released since 2010 (in particular new releases often enter high and then fall out of the list over a month or two), but the current list has films as old as 1928 (The Passion of Joan of Arc) that weren’t there back in 2010. So keeping up to date is not simply a matter of watching new releases. The best way to watch the list is terrestrial TV There were various methods I used to watch the list. Some I’d seen in the cinema when they came out (or was able to catch that way anyway - the QFT showed Duck Soup, for example). Netflix and Amazon Video had some films, but overall a very disappointing percentage. The QUB Library, as previously mentioned, had a good number of DVDs on the list (especially the older things). I ended up buying a few (Dial M for Murder on 3D Bluray was well worth it; it’s beautifully shot and unobtrusively 3D), borrowed a few from friends and ended up finishing off the list by a Lovefilm one month free trial. The single best source, however, was UK terrestrial TV. Over the past 6 years Freeview (the free-to-air service here) had the highest percentage of the list available. Of course this requires some degree of organisation to make sure you don’t miss things. Films I enjoyed Not necessarily my favourite, but things I wouldn’t have necessarily watched and was pleasantly surprised by. No particular order, and I’m leaving out a lot of films I really enjoyed but would have got around to watching anyway. Clint Eastwood films - Gran Torino and Million Dollar Baby were both excellent but neither would have appealed to me at first glance. I hated Unforgiven though. Jimmy Stewart. I’m not a fan of It’s a Wonderful Life (which I’d already watched because it’s Lister’s favourite film), but Harvey is obviously the basis of lots of imaginary friend movies and Rear Window explained a Simpsons episode (there were a lot of Simpsons episodes explained by watching the list). Spaghetti Westerns. I wouldn’t have thought they were my thing, but I really enjoyed the Serg[...]



The terrible PIC ecosystem

Sun, 25 Dec 2016 00:51:27 +0000

I recently had call to play with some 1-Wire devices at work (more of which in a future post). It was taking a while for the appropriate programmer to turn up, so of course I pulled out my trusty BusPirate. It turned out the devices in question would only talk in overdrive mode, while the Bus Pirate could only offer standard mode. So I set about trying to figure out how to add the appropriate support.

This is is a huge endorsement for test equipment with Free Software firmware. Rather than giving up I was able to go and grab the current firmware, which has been adopted by the community since Dangerous Prototypes have discontinued development. What let me down was the ecosystem around the PIC24FJ64GA002.

My previous recent experience with microcontrollers has been with the ATTiny range and the STM32. Getting up and running with both of these was fairly easy - the tool chains necessary were already present in Debian, so all it took was a simple apt invocation to install everything I needed to compile code and program it to the devices.

Not so with the PIC series, which surprised me. There seems to be some basic support for the earlier PIC16 range, but for later chips there’s nothing that works out of the box with Debian. Investigation revealed that this was because there’s nothing maintained that enabled Free development for the PIC range. The accepted solution is the closed MPLAB X. Now, in one sense fair play to Microchip for making this available. But in another, shame on you. I can’t imagine ever choosing to build something based on a chip that only had a closed source tool chain available. I want things I can use in Makefiles and properly script, that are available in my distro of choice and that generally work in the same fashion as the tool chains I’m used to. I understand there might be some benefit in a closed compiler in terms of performance (and have HPC friends who would never trust a benchmark provided using GCC), but in general that’s not the space I move in. Nor does it seem to be the sort of attitude you should be taking if you are trying to attract the hobbyist and small production run market.

Any yet this seems common amongst hardware manufacturers. People whose core business is selling physical items, where the software is only relevant in terms of being able to use those items, seem to consider the software to be precious. Instead of opening up programming specifications and allowing a more widespread use of the hardware, increasing sales. I understand there are some cases where this isn’t practical, but the default attitude is definitely one of being closed rather than open, which is a terrible shame.

Anyway. I do have some Bus Pirate 1-Wire overdrive support now working (pending some testing to ensure standard mode still works), but I am glad I never spent a lot of time getting involved with PICs now.




Timezones + static blog generation

Sun, 18 Dec 2016 23:28:36 +0000

So, it turns out when you move to static blog generation and do the generation on your laptop, which is usually in the timezone you’re currently physically located, it can cause URLs to change. Especially if you’re prone to blogging late at night, which can result in even just a shift to DST changing things. I’ve forced jekyll to UTC by adding timezone: 'UTC' to the config, and ensuring all the posts now have timezones for when they were written (a lot of the imported ones didn’t), so hopefully things should be stable from here on.




No longer a student. Again.

Mon, 12 Dec 2016 22:27:25 +0000

(image)

(image courtesy of XKCD)

Last week I graduated with a Masters in Legal Science (now taught as an MLaw) from Queen’s University Belfast. I’m pleased to have achieved a Distinction, as well an award for Outstanding Achievement in the Dissertation (which was on the infringement of privacy by private organisations due to state mandated surveillance and retention laws - pretty topical given the unfortunate introduction of the Investigatory Powers Act 2016). However, as previously stated, I had made the decision that I was happier building things, and wanted to return to the world of technology. I talked to a bunch of interesting options, got to various stages in the hiring process with each of them, and happily accepted a role with Titan IC Systems which started at the beginning of September.

Titan have produced a hardware accelerated regular expression processor (hence the XKCD reference); the RXP in its FPGA variant (what I get to play with) can handle pattern matching against 40Gb/s of traffic. Which is kinda interesting, as it lends itself to a whole range of applications from network scanning to data mining to, well, anything where you want to sift through a large amount of data checking against a large number of rules. However it’s brand new technology for me to get up to speed with (plus getting back into a regular working pattern rather than academentia), and the combination of that and spending most of the summer post DebConf wrapping up the dissertation has meant I haven’t had as much time to devote other things as I’d have liked. However I’ve a few side projects at various stages of completion and will try to manage more regular updates.




Confirming all use of an SSH agent

Sun, 03 Jul 2016 15:55:40 +0000

For a long time I’ve wanted an ssh-agent setup that would ask me before every use, so I could slightly more comfortably forward authentication over SSH without worrying that my session might get hijacked somewhere at the remote end (I often find myself wanting to pull authenticated git repos on remote hosts). I’m at DebConf this week, which is an ideal time to dig further into these things, so I did so today. As is often the case it turns out this is already possible, if you know how.

I began with a setup that was using GNOME Keyring to manage my SSH keys. This isn’t quite what I want (eventually I want to get to the point that I can sometimes forward a GPG agent to remote hosts for signing purposes as well), so I set about setting up gpg-agent. I used Chris’ excellent guide to GnuPG/SSH Agent setup as a starting point and ended up doing the following:

$ echo use-agent >> ~/.gnupg/options
$ echo enable-ssh-support >> ~/.gnupg/gpg-agent.conf
$ sudo sed -i.bak "s/^use-ssh-agent/# use-ssh-agent/" /etc/X11/Xsession.options
$ sudo rm /etc/xdg/autostart/gnome-keyring-ssh.desktop

The first 2 commands setup my local agent, and told it to do SSH agent foo. The next stopped X from firing up ssh-agent, and the final one prevents GNOME Keyring from being configured to be the SSH agent, without having to remove libpam-gnome-keyring as Chris did. After the above I logged out of and into X again, and could see ~/.gnupg/S.gpg-agent.ssh getting created and env | grep SSH showing SSH_AUTH_SOCK pointing to it (if GNOME Keyring is still handling things it ends up pointing to something like /run/user/1000/keyring/ssh).

[Update: Luca Capello emailed to point out this was a bad approach; there’s thankfully no need to do the last 2 commands that require root. #767341 removed the need to edit Xsession.options and you can prevent GNOME Keyring starting on a per user basis with:

(cat /etc/xdg/autostart/gnome-keyring-ssh.desktop ;
 echo 'X-GNOME-Autostart-enabled=false') > \
 ~/.config/autostart/gnome-keyring-ssh.desktop

]

After this it turned out all I need to do was ssh-add -c . The -c says “confirm use” and results in the confirm flag being appended to the end of ~/.gnupg/sshcontrol (so if you’ve already done the ssh-add you can go and add the confirm if that’s the behaviour you’d like).

Simple when you know how, but I’ve had conversations with several people in the past who wanted the same thing and hadn’t figured out how, so hopefully this is helpful to others.




Hire me!

Mon, 27 Jun 2016 22:21:20 +0000

It’s rare to be in a position to be able to publicly announce you’re looking for a new job, but as the opportunity is currently available to me I feel I should take advantage of it. That’s especially true given the fact I’ll be at DebConf 16 next week and hope to be able to talk to various people who might be hiring (and will, of course, be attending the job fair).

I’m coming to the end of my Masters in Legal Science and although it’s been fascinating I’ve made the decision that I want to return to the world of tech. I like building things too much it seems. There are various people I’ve already reached out to, and more that are on my list to contact, but I figure making it more widely known that I’m in the market can’t hurt with finding the right fit.

  • Availability: August 2016 onwards. I can wait for the right opportunity, but I’ve got a dissertation to write up so can’t start any sooner.
  • Location: Preferably Belfast, Northern Ireland. I know that’s a tricky one, but I’ve done my share of moving around for the moment (note I’ve no problem with having to do travel as part of my job). While I prefer an office environment I’m perfectly able to work from home, as long as it’s as part of a team that is tooled up for disperse workers - in my experience being the only remote person rarely works well. There’s a chance I could be persuaded to move to Dublin for the right role.
  • Type of role: I sit somewhere on the software developer/technical lead/architect spectrum. I expect to get my hands dirty (it’s the only way to learn a system properly), but equally if I’m not able to be involved in making high level technical decisions then I’ll find myself frustrated.
  • Technology preferences: Flexible. My background is backend systems programming (primarily C in the storage and networking spaces), but like most developers these days I’ve had exposure to a bunch of different things and enjoy the opportunity to learn new things.

I’m on LinkedIn and OpenHUB, which should give a bit more info on my previous experience and skill set. I know I’m light on details here, so feel free to email me to talk about what I might be able to specifically bring to your organisation.




Fixing missing text in Firefox

Thu, 23 Jun 2016 14:23:59 +0000

Every now and again I get this problem where Firefox won’t render text correctly (on a Debian/stretch system). Most websites are fine, but the odd site just shows up with blanks where the text should be. Initially I thought it was NoScript, but turning that off didn’t help. Daniel Silverstone gave me a pointer today that the pages in question were using webfonts, and that provided enough information to dig deeper. The sites in question were using Cantarell, via:

src: local('Cantarell Regular'), local('Cantarell-Regular'), url(cantarell.woff2) format('woff2'), url(cantarell.woff) format('woff');

The Firefox web dev inspector didn’t show it trying to fetch the font remotely, so I removed the local() elements from the CSS. That fixed the page, letting me pinpoint the problem as a local font issue. I have fonts-cantarell installed so at first I tried to remove it, but that breaks gnome-core. So instead I did an fc-list | grep -i cant to ask fontconfig what it thought was happening. That gave:

/usr/share/fonts/opentype/cantarell/Cantarell-Regular.otf.dpkg-tmp: Cantarell:style=Regular
/usr/share/fonts/opentype/cantarell/Cantarell-Bold.otf.dpkg-tmp: Cantarell:style=Bold
/usr/share/fonts/opentype/cantarell/Cantarell-Bold.otf: Cantarell:style=Bold
/usr/share/fonts/opentype/cantarell/Cantarell-Oblique.otf: Cantarell:style=Oblique
/usr/share/fonts/opentype/cantarell/Cantarell-Regular.otf: Cantarell:style=Regular
/usr/share/fonts/opentype/cantarell/Cantarell-Bold-Oblique.otf: Cantarell:style=Bold-Oblique
/usr/share/fonts/opentype/cantarell/Cantarell-Oblique.otf.dpkg-tmp: Cantarell:style=Oblique
/usr/share/fonts/opentype/cantarell/Cantarell-BoldOblique.otf: Cantarell:style=BoldOblique

Hmmm. Those .dpkg-tmp files looked odd, and sure enough they didn’t actually exist. So I did a sudo fc-cache -f -v to force a rebuild of the font cache and restarted Firefox (it didn’t seem to work before doing so) and everything works fine now.

It seems that fc-cache must have been run at some point when dpkg had not yet completed installing an update to the fonts-cantarell package. That seems like a bug - fontconfig should probably ignore .dpkg* files, but equally I wouldn’t expect it to be run before dpkg had finished its unpacking stage fully.




First steps with the ATtiny45

Wed, 18 May 2016 21:25:52 +0000

(image)

These days the phrase “embedded” usually means no console (except, if you’re lucky, console on a UART for debugging) and probably busybox for as much of userspace as you can get away with. You possibly have package management from OpenEmbedded or similar, though it might just be a horrible kludged together rootfs if someone hates you. Either way it’s rare for it not to involve some sort of hardware and OS much more advanced than the 8 bit machines I started out programming on.

That is, unless you’re playing with Arduinos or other similar hardware. I’m currently waiting on some ESP8266 dev boards to arrive, but even they’re quite advanced, with wifi and a basic OS framework provided. A long time ago I meant to get around to playing with PICs but never managed to do so. What I realised recently was that I have a ready made USB relay board that is powered by an ATtiny45. First step was to figure out if there were suitable programming pins available, which turned out to be all brought out conveniently to the edge of the board. Next I got out my trusty Bus Pirate, installed avrdude and lo and behold:

$ avrdude -p attiny45 -c buspirate -P /dev/ttyUSB0
Attempting to initiate BusPirate binary mode...
avrdude: Paged flash write enabled.
avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.01s

avrdude: Device signature = 0x1e9206 (probably t45)

avrdude: safemode: Fuses OK (E:FF, H:DD, L:E1)

avrdude done.  Thank you.

Perfect. I then read the existing flash image off the device, disassembled it, worked out it was based on V-USB and then proceeded to work out that the only interesting extra bit was that the relay was hanging off pin 3 on IO port B. Which led to me knocking up what I thought should be a functionally equivalent version of the firmware, available locally or on GitHub. It’s worked with my basic testing so far and has confirmed to me I understand how the board is set up, meaning I can start to think about what else I could do with it…