The Ware for August 2013 was an APC Mobile Power Pack, model number UPB10. I bought it several years ago, apparently before they had efficient single-chip solutions for battery packs. One of the nice things about this pack is it provides a “true” 1.6A at 5V output, i.e. it can pump out that current until the battery is depleted, unlike cheaper packs which may be rated for about that much current but can only supply it for short bursts before the internal regulators overheat and shut down. The pack itself serviced me well for years, until the ultrasonic welds that held together the case-halves failed, spilling its guts, and giving us last month’s ware in that process.
Lots of people guessed it was a power pack, but Kevin was the first to call the exact model and make. Congrats, email me for your prize.
I went to Burning Man for the second time this year. I had an amazing time hanging out with so many interesting and fun people. I spent many a night dancing to the beats of the Robot Heart again, taking in 85,000 watts of pure, uncut bass: it’s where silicon touches the soul. If you haven’t been to Burning Man, this article gives the most balanced perspective I’ve seen to date.
This year, as in my previous year, I camped with a group called The Phage, which is part of a three-camp complex known as The Institute (the other two camps are Relaxomatic and False Profit). The camp doesn’t happen without a lot of planning and preparation, but coming from Singapore, it’s hard to be very useful in pre-camp prep. So I did what I could do — make circuit boards.
The Phage camp’s logo is a stylized version of the bacteriophage virus, so I made a custom-styled “locator badge” for our camp this year.
I also made, more or less on a whim, a small driver board for WS2812B-style LED strips.
Below is a short movie of the two in action (sorry IE & Safari users, I only do Ogg Theora).
It’s a unique experience to see your creations being picked up, loved, and then utterly abused for an entire week. It’s even more amazing to get feedback from such friendly, understanding and intelligent users. I spent several splendid afternoons with a soldering iron, teaching people how to solder, as well as fixing and prodding various bits of hardware. As an old-school hacker there are few things more relaxing than sitting around on a lazy afternoon, drinking beers, soldering, and making new friends — and not having to worry about rushing off to my next meeting, completely free of the distractions of the Internet and mobile phones.
Phage Locator Badges
In addition to being a source of light at night, the badges have a “locator” feature. Every badge contains a 433 MHz radio transceiver. On top of this, I built a broadcast paging system so badge-wearers can press a button and cause other people’s badges to strobe in response.
I also attached a high-gain receiver to our art car, Strangelove, so some of the art car’s LED strips would also strobe when the car’s receiver detected a locate request from a badge.
There’s also a huge flame-shooting art piece on our frontage called the “Hive Queen” (on the left in the photo above). Normally, users have to walk up to it and hit buttons to make it shoot fire. Well, after a few beers, someone suggested it would be a good idea to hack another receiver into the Hive Queen (thank you Sean Stevens for loaning me the relay breakout board!). It required a few code changes to ensure that nobody could jam the fire control solenoids on, but it worked.
It’s the first time I’ve ever built a circuit that intentionally caused fire; there’s something viscerally satisfying about remote-controlling six flame throwers at once.
Only 50 of such badges will ever be made, but I figured I’d share the design files so others thinking about doing something similar could benefit. Click the various links for schematics (PDF), gerbers, and PCB source (Altium). You can also find all the firmware for the radio and blinky lights in the Phage git repo.
Compact LED Strip Drivers
The intent behind the LED strip driver was to provide a compact and minimal way to drive cut-to-length LED strips, so that no programming is required at the point of installation. An important feature is the ability to automatically measure the length of an LED strip loop, and adjust the pre-programmed light patterns accordingly. The board was made out of flex circuit material and included a microphone circuit that you could cut off with a pair of scissors, giving an extra dimension of customization with minimal tools.
I was happy to see the number of creative ways people used the LED strip drivers — they were worn as belts, around hats, zip tied to bikes, bags, etc. It was also very instructive to observe how these things failed — at Burning Man, the strips were thoroughly used; they had to survive a week of trudging around the desert, and the repetitive stress of hours of dancing.
I’m also sharing the source for the LED strip driver I made: schematics (PDF), gerbers, and PCB source (Altium). Firmware can be found at this github repo. As a final note, I wouldn’t recommend anyone actually fabricate the designs as-is — please consider them reference material only. There are some flaws in both designs, particularly the flex LED driver. Many things went right, but I would also do many things differently now that I’ve seen how people use them. But, for those who have never done a flex PCB before, the files do give you a taste of some of the quirks that go into making a flexible PCB.
The Ware for July 2013 is a Motorola 68851 PMMU, courtesy of Andreas Ehliar. I look forward to seeing many more beautiful die shots of retro-ware like this at his blog over the coming months….here are his notes about the ware:
I got this chip from a colleague together with a 68020 and a 68881. I initially thought this particular chip would be the least interesting, but so far it is my favourite of these due to the unexpected complexity.
My first guess was that it would essentially just consist of a CAM memory, but an initial inspection using a stereo microscope revealed that there was a very interesting memory structure to the right which I guessed was a microcode memory (since I have seen a similar looking memory in the 68000). A look at the manual [1] actually confirmed this, as the manual surprisingly reveals that a two level control store is used. A simplified block diagram which is suspiciously similar to the actual layout of the chip (see figure 1-2) is also included.
However, the low level details can be found in an article in IEEE Micro which actually contains a (very low res) die photo as well [2].
Other low level details can probably be found in some Motorola patents regarding PMMU’s as well, although the 68851 is never named by name here. (However, 68020 specific terminology is used such as CALLM/RTM. See for example figure 2 in [3].
Anyway, it turns out that putting the MMU off-chip was most likely a pretty bad decision, as the 68030 proved that it is much more efficient to have the MMU on-chip rather than off-chip. (See the chip photo of a 68030 on Wikipedia where the MMU can be seen in the upper left corner if I understand things correctly.) (The 68030 is actually very similar to a 68020 in terms of the layout, the part in the upper left corner is one of the few things that seems to be changed, as well as what I assume to be an added data cache to the right.
I think this could be interesting as a ware because the microcode memory would (probably) cause you to think about processors, although the rest of the chip doesn’t really look like a processor. (Too much memory for this time period, no real execution unit, etc.)
Nobody managed to guess this one, so it’s hard to pick a winner. I liked reading Taniwha’s explanations and thoughts, so I’ll declare Taniwha the winner. Email me for your prize!
Consumers tend to throw away old gadgets with little fanfare or thought. I think that’s a shame; all the knowledge and experience gained navigating the quirks of the old gadget are tossed as well. Thus, instead of raving about the latest greatest gadget, I like to jot down a few notes about my old gadgets when I retire them.
The third installment of my exit review series (previous installments were on the IBM T60p and the Blackberry 8700c) was done as a guest writer for medium.com; read it here.
