Cloning a USB LED device

Jan 14, 2017 / 0 comments

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

Jan 6, 2017 / 0 comments

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.

Dec 31, 2016 / 0 comments

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 Sergio Leone films (A Fistful of Dollars etc.). You can see where Tarantino gets a lot of his inspiration.
  • Foreign language films. I wouldn’t normally seek these out. And in general it seems I cannot get on with Italian films (except Life is Beautiful), but Amores Perros, Amelie and Ikiru were all better than expected.
  • Kind Hearts and Coronets. For some reason I didn’t watch this until almost the end; I think the title always put me off. Turned out to be very enjoyable.

Films I didn’t enjoy

I’m sure these mark me out as not being a film buff, but there are various things I would have turned off if I’d caught them by accident rather than setting out to watch them.

I’ve kept the full list available, if you’re curious.

The terrible PIC ecosystem

Dec 25, 2016 / 0 comments

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

Dec 18, 2016 / 0 comments

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.

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