Category: hardware

Yet another router upgrade

It’s been a while since I’ve done something really… EPIC. Like, REALLY EPIC. And that doesn’t sound nice, so I decided to pick another router and make it EPIC.

This time I picked a nice Mercury MW4530R, which is known to be supported by OpenWRT trunk (No bloody Openwrt patching/hacking this time, so no pain in rebasing a patchset on every update), and for 60$ is a deal. So, I got the hardware, and set down to work. Since a few people asked this time I even took the time to record a small video of the whole build. My thanks fly out to Dmitry Zganyaiko for his awesome music.

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Antares 0.2-rc1 released!

That’s it! It’s out. After two years of slow and steady development in my free time. Antares is a free and open source (GPLv2) buildsystem bundled with library code, aimed at bare metal targets. Sounds scary? Well, consider this an arduino for kernel hackers. If you are one – you have all the regular tools here: kconfig, GNU/Make, and no need to write Makefiles from scratch or collect sparse instructions over the web – just bootstrap a project, adjust the config to your needs and go!
0.2-rc1 is the first release that can be considered (more or less) stable for every day use. To find more about what it is and how it works – check out the README in Russian or English

snapshot9

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Madskills of the year: a quick and dirty HC-05 adapter

Do you remember those small bluetooth to uart modules called HC-05? Those that are sold cheap in bulk from those chineese resellers. Anyway, if you remember, they are configured via AT commands, before being installed into they final place. I needed to configure a bunch of those modules, so I needed an adapter. Since I haven’t yet assembled a CNC mill, nor I had the time to visit people who have a nice CNC mill, nor I had the time to etch a board, I decided to go ultra-cheap and ultra-dirty.
Out of the junk I took a piece of clear acrylic, drilled the holes added a little mess-of-wires, a button and secured everything with hot glue.

The result looked ugly as hell, but worked anyway.

IMG_20130901_012857
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UBIFS over DVD+RW

Don’t ask why. I just though it might be a cool idea.

So what’s the catch? Packet writing over CD/DVD-/+RW media is pretty much the same as writing to a block device. The only bad thing is that:

  • Writes MUST be aligned
  • Writes must be of a fixed packet size
  • Before reading you must issue a flush command.

To hide this from the upper level pktcdvd module exists that assembles packets and sends them to the media. Well, this whole pktcdvd machinery reminded me of a NAND device actually, so I wondered if we could actually make an MTD device out of a CD or DVD. AND run UBIFS on top of it. (Or yaffs2. whatever). Details&code under the cut

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A DIY air filter for all those soldering works.

Modern solder flux are scary. Period. Once, I ordered a professional flux and a quick read through the ‘consequences’ of it’s usage looked like a damn curse to me: Cancer, birth defects etc. You don’t have to be Ph.D. in biology to get that this flux must be a hell of a mutagen, so I decided to put it somewhere far away. Anyway, rosin was and is my flux of choice. It’s much safer, but still not ideal. You do have to filter the smoke anyways from their selection, unless you are fond of headaches. So, this project was just asking to be done:

IMG_20130701_015237

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Again: Fake USB 2.0 hubs

USB hubs are a thing I prefer to stock on, since I really often use these in my projects . Threrefore, just when I was running low on ’em, I ordered a bunch in bulk from china. Took about a month, till our slowpoke-post delivered those.
Anyway, being pessimisticby default, I started by doing an lsusb -vv on the hub device:
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Ditching the x86 – moving on to armv7l

My home server has a long story. It all started with a Pentium 4, an old 20GB HDD and FreeBSD 6.2 … hell, I don’t even remember the exact year.
Anyway, after a few years, the hardware was finally put to rest, since it died and got resurrected thrice, I got an Intel Atom D410-based miniATX board, switched to linux, first debian, then agilia, then arch… Anyway, it used to be a nice server for personal needs, that crashed only on occasional HAD-effect, so it was… sufficient.
Now, the time has come to move on, to arm. The benefits were simple and straight:

  • 10W peak power consumption
  • Fully passive cooling
  • eMMC for the root partition
  • 4 cores!
  • Always a serial terminal, starting from uboot phase, so that I don’t have to carry a monitor to the closet where it is stationed.

I picked ODROID-X2 based around Exynos4212 Prime. ODROID-U2 looked worse, since had NAND soldered onboard. eMMC looked easier to replace. And the benchmarks said eMMC was faster.

IMG_20130521_133759

So, here go my adventures with this hardware.
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solidoodle: pushing the thing to the limits. 0.050 mm layers.

It’s been a while, since I’ve posted a anything  about this shiny toy of mine. This doesn’t mean I’m doing nothing about it. And I’m adding a hack every weekend or two. Unfortunately, this is definitely NOT the thing you can grab and start printing happily, as are most of the sub – 5k$ printers. ( Don’t believe the marketing BS!)

So far, I’ve added a better filament feed, a usb camera mount, a cooling fan, fixed the Z axis wobble… partly…

Well, last time I replaced the lead nut with a custom higher one, I had a very slight wobble remaining. This one was due to the fact that the centers of the Z axis rod and the motor shaft were not perfectly aligned. That was still a little bit too annoying, when it came to 0.1mm prints. lawsy recently made a fix in the firmware but adding another variable that needs experimental calibration certainly doesn’t fit what I wanted. Anyway, 5/16 rod also annoyed the hell out of me (I prefer metric stuff, that’s my religion, bear with it!), so I decided to make a mechanical fix first. And the idea was to throw away that crap, and place something better.
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There’s a server in my pocket!

I’m not a psychopath, I’m just very creative.
(c) Harry Potter and the Methods of Rationality

Taking part in competitions like “eurobot”, where you have to do some coding in extreme conditions, on/under a table, on the floor, etc. and a few other trips like that convinced me that I should definitely make something more of my cell phone. Something, that will help me out in this case.

So, we have:

  • A dumb brick called ‘HD7 Pro’ from china, with android 2.3.5. One and a half years old.
  • /dev/brains
  • A few hours of free time

What we want to get:

  • A portable server with lighttpd, ssh, git, etc
  • WiFi AP with local dns, internet tethering (if we’re not roaming!)

2013-03-18-00-19-06

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