A few days ago an appeals court in the US has substantially reduced the amount of patentable non-things: business-method patents were flushed down the drain. To-be-patented thingies are to be scrutinised a lot more before a patent can be granted. Software gets harder to patent.

More on this quite interesting issue at groklaw.

[ published on Fri 14.11.2008 13:05 | filed in interests/anti | ]

(Somewhat) apropos yesterday's article on tinkering: I wanted a simple setup to mount my Treo phone/pda in the car. None of the kludges for sale impressed me favourably, all being expensive/clunky/both or worse.

Being the Dismantler and Recycler Of Crap that I am, I have a few dead hard disks sitting around. Dead hard disk = two large and strong magnets, iff you manage to get them off their backing without breaking the brittle material. Sometimes I do manage, sometimes I don't.

So here's my ghetto mount: a fat magnet in heatshrink tubing, embedded in the back of a slab of coreflute which is stickytaped to the car dash. The Treo-side consists of a bit of thin sheet metal (was once part of a floppy drive housing) taped to the back of the treo with super-thin packing tape.

 mag ghetto mount mag ghetto mount mag ghetto mount

The hard disk magnet is easily strong enough to work through one layer of heatshrink, coreflute, the silicon glove and the packing tape. With the packing tape no irreversible mods to the Treo are necessary.

Simple, neat and zero-cost. I like that.

[ published on Tue 11.11.2008 13:26 | filed in interests/tinkering | ]

It's Conny's laptop and I'll paint if she wants that.

Actually, she does, and not surprisingly, I did. She wanted a skull and crossbones design and who am I to object to that Sound Sensible Choice :-)

 conny laptop deco conny laptop deco

I found a tiny image on the web and used that as an inspiration to come up with this design. Then I reused an old conference presentation slide and cut that for a mask, and went shopping for paint: fluoro pink.

 laptop painting laptop painting

The mask I fixed to the lapdog lid with spray glue (sprayed onto the mask, of course), and then I rattlecan-sprayed four layers: plastic primer, a thin coat of silver as a lightening base and two layers of pink.

 connys laptop painted

Removed the mask, cleaned the glue residue off and neatened some of the spots where I had been too generous with the paint (raised edges). The stupid pink paint decided not to be very fluorescent (even with the silver base), but pink it is. Another coat of gloss enamel for the whole lid is forthcoming, but Conny is pleased with the result - and so am I.

[ published on Tue 11.11.2008 13:11 | filed in interests/tinkering | ]

I just saw a really interesting article, titled reflections on tinkering. Recommended.

[ published on Mon 10.11.2008 09:49 | filed in interests/tinkering | ]

My newish Treo 680 has blue teeth, which is better than a kick in selfsame (but not very much as shoddily as it was implemented by Palm). Being only a moderate gadgeteer (and far from rich) I've been lusting after a good/cheap/simple (yeah, I know RFC1925) navigation setup for the car - and cable-less as much as possible.

So I got a cheap Bluetooth GPS receiver which is branded "HP iPAQ Bluetooth GPS BTG-10H". Interestingly that model seems to have been orphaned by HP and is now sold under the name Siraya. $20 for a new 12-channel receiver with data logging, some other goodies and a car charger; not bad I think.

A bit of digging determined that it uses an iTrax03 GPS chip made by Fastrax, a Finnish company.

Now I don't know about Finnish attitudes towards the Dutch in general, but this Finnish piece of electronic wizardry absolutely killed the Dutch fount of navigational wisdom. (Apropos nothing in particular: the Dutch have a reputation as lousy drivers all across the mountainous parts of Europe.)

Tomtom Navigator 6 works quite well - when it works at all. Specifically Treos and Bluetooth receivers are well known sources of horrible interoperability problems. Same here: my receiver gets a fix moderately quickly and the TomTom shows the way, but after no more than 10 minutes the TomTom locks up my Treo completely - until the GPS is switched off or the BT connection is lost.

This obviously sucks, and is a tale of woe oft repeated elsewhere on the intertubes.

I am, however, really stubborn about fixing problems. So I started digging through all the horror stories, tried all kinds of suggested things, learned a bit about NMEA, to no avail - until the really simple, really stupid cause dawned on me: During a session with a serial terminal reading the NMEA data from the iTrax I realized that the volume of stuff it sends is quite..substantial.

The FasTrax docs about NMEA and their chips are quite good. NMEA has a bunch of required and optional messages, and I learned that for barebones navigation one only needs RMC messages as often as possible; if one also wants to know things like satellite positions and fix quality, one needs GSA and GSV.

Other GPSs seem to have configurable separate output rates for these messages; most tips I found mentioned setting RMC to 1/sec and GSA/GSV to once every 5 secs - which makes a lot of sense, because there will be multiple GSV messages depending on the number of satellites in view.

Not so with the iTrax: you can configure the output rate very precisely (up to 5Hz) but only one rate for all messages - and by default it spews its (nonstandard) figure-of-merit message as well as a full set of GSVs every second. At least on the Treo this overwhelms TomTom after a few minutes (which sounds like very shoddy programming to me) and everything locks up hard.

The fix? Get rid of the GSV messages: you do lose the per-satellite signal quality and azimuth/elevation info, but that's all. The satellite status screen simply shows blank bars with the satellite number and the GGA and GSA messages still tell the TomTom enough to know how many and which satellites are in use and how good the nav fix is, so all is well.

FasTrax has made configuring the iTrax very simple: you send it ascii (nonstandard-but-NMEA-formatted) commands over the serial/BT connection and it stores them persistently in flash, done. I used BT Serial on the Treo, which works very well.

The online docs have all the necessary configuration info and the only thing you'll actually have to do is send it this one message, once:


22 is the SYS_NMEA_MASK parameter, controlling which messages you want, and A002 means "send only RMC, GGA and GSA". (The default mask is A023, which includes the above plus FOM and GSV. Sending $PFST,CONF,22 shows you the current value of that parameter.)

Wasn't that easy?

[ published on Wed 05.11.2008 00:00 | filed in brainfarts | ]

So you have a nice, nifty RC car which is shiny and very fast (and therefore cool) or dirty and really slow (and therefore cool) and yet you are unhappy with its turning radius?

You might consider rigging it for four-wheel steering, which is very nice for tight turns but not so much fun or stable for high-speed runs. Which do you choose, stability and 2WS or tight turns and 4WS? Can't one have both?

Indeed you can. Faced with this very challenge for my Wheely-King-based rock crawler, I've built a four-wheel steering controller (4WSC) which gives you that choice and lots more, provided that you have a radio with one free channel: with that channel you can switch between proportional four-wheel steering, two-wheel steering front or rear and crabbing, on the go and without stopping. Your one steering wheel controls both servos appropriately, based on your chosen mode of operation. The 4WSC also includes a servo reversing cabability for your year servo and is configured/programmed using your rc transmitter.

You might have a look at the manual to see what other goodies I managed to program in.

Here is what the 4WSC looks like: tiny (that's a 1cm grid) but quite capable and cool.

 4wsc production model

As always with my stuff, it's open source software: the commented source code is available right here for your perusal/modifications/other weird applications. Share and Enjoy. You might almost call the 4WSC an example of "open source hardware": I'm also providing a printable circuit board design, ready for making your own pcb's with the toner transfer method.

The hardware side of the 4WSC is really simple: it is microcontroller-based, uses a PIC12F635 or 12F683 or similar, and because PICs are great devices it does not need any external components (except for plugs/leads and a buzzer). All you need to build your own is such a microcontroller, a PIC programmer interface for programming it, soldering gear and either some protoboard or minimal PCB-making skills.

If that sounds too tedious/complicated, you can simply pay me a little money and get one finished and ready: I made a few of the controllers and am sufficiently happy with the outcome to sell them. Contact me here and we can discuss the details; I might also do custom firmware for your specific requirements (for a fee, mind you).

For the do-it-yourself afficionados (like me) here are the goodies:


[ published on Tue 04.11.2008 14:44 | filed in mystuff | ]

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