Space Oddity

Not much to report right now, so I'll just blather on about Space Oddity.

So, I'm working on an iPad thing - to be revealed in a couple of months - that requires access to multitrack recordings to test its functionality. The only multitrack recording I have is Space Oddity - if you remember the 8 stems were released a few years back, possibly for the 40th anniversary in 2009. As a result of this combination of factors, I am listening to Space Oddity - sometimes in a screwed-up, distorted, hoppy and skippy version - around 40 times a day. Every day. Have been for weeks.

Now any other song, that would have driven me insane. But Space Oddity is so utterly magnificent that it stands up to dozens and dozens and hundreds and thousands of repeat listens.

So there you  go. Told you I didn't have much to report right now, I'm kinda busy paying the rent, all the while listening to Mellotrons and Stylophones and young men with spiky orange hair counting down from 10 to zero. Actually, all that record needs to make it even more perfect is Mick Ronson, but the next 4 years of his recorded output did have Mick Ronson, so maybe you can't win 'em all.

Maybe some Pi stuff to report in a couple of weeks ...

Not *Quite* So Teeny Tiny TV

Yet another display, NQSTTTV is an interesting compromise - 4" diagonal (compared to the 3.5" of TTTV and the 7" of NSTTTV), and it consumes just 132mA (measured) from the 12v line. This means if I run 7 of these for the Players and the Conductor, and if their current draw is consistent, I am *just* under 1A, and comfortably within 1.2A, an easily obtainable wall wart 12v supply. Also, the physical dimension of these allows me to just about fit 6 of them (with minor juttage) onto an A4 laser cut ply sheet. AND - triple plus - they support 16:9.

Downside - they seem pretty unreliable and may just croak at any moment. But hey, they are cheap ... and I can fit them onto an A4 backing, I can power all of them from a single wall wart, and I can run them 16:9 so they fit a little more tightly together as a Teeny Tiny Arty Installation.

p.s. I still fancy building a 12" tall synthpop band out of Action Men, with a backdrop of these TVs. It would be ridiculous but funny - the Bonsai League anybody? Subhuman League? A synthpop cover of Elton's Tiny Dancer would be called for to celebrate construction of the micro marvel. Maybe I could buy Kraftwerk action figures - they must be available if you can buy Johnny, Joey and Dee Dee.

Assemble the musicians ...

I've made a single 'PIANA' PCB (with all the MIDI gubbins so it can be played from a MIDI keyboard), and these are 6 'Player' PCBs, to be driven directly by a 3v3 serial from the Conductor. Eagle-eyed veviews will notice that I have not yet soldered in a resistor between the LED and ground. That's because I haven't yet decided what value resistor to stick in there - I may drop it quite low and go for retina-melty brightness. With only one of them and one PIC I can throw about 20mA at the LED if I choose to. 

Also, I didn't buy enough 10uF capacitors, so have only decoupled 5v - not smart, having soldered it all up, I should have stuck the single cap onto 3v3, particularly if I really am going to start dumping current like a lunatic through the LED. Oh well, another order from CPC beckons ... 

Player vs. PIANA

Here's a note for myself rather than you lot - a record of the bits I need to solder onto the PCB to make a Player node for the Chamber Orchestra, rather than a full-blown PIANA.

So the dongle, sorry, I meant PIC, the LED and its resistor, header for serial in, USB for power in and header for power out (to Teeny Tiny TV), a wire bridge to connect Pi Rx from serial in rather than MIDI in (via the opto), the GPIO connector, and the 3 capacitors.

Player PCBs back from China!

These puppies arrived today from the mighty Seeedstudios - still cannot quite believe that I can make PCBs for under 90p each ...

Despite ordering 10 they shipped me 12, just enough to make 2 entire Chamber Orchestras. I assume they yielded well as the board is ridiculously simple - excellent!!

Comment moderation

Sorry, I hate doing this, but some dweeb / dweebbot is spamming the blog with 'Cheap Flights to Jeddah' nonsense, so I have introduced a level of comment moderation. Sorry if this is a pain in the rear, but I hate that kind of crap and it has to stop.

In the meantime, here's a revised Conductor, taking into account a certain tightness around the resistors on the original, and the very real requirement for support from below, hence the mount hole, which made routing even harder than before!

Conductor is go!

Alternative title - "These PICs are a BUGGER to get right" - I think 4 different registers were incorrectly initialized, and because I didn't have space to design in any in-circuit programming I have to lever out a chip, program it, stick it back in, run tests, tear out hair, repeat ... 

But here we are at last with as far as I can tell a perfectly good PIC image for the Conductor. And for the purposes of initial experimentation I don't even need a Player PCB, I can just lash Tx[n] on the Conductor to Rx on each Player, and start Chamber Orchestring.  

This is pretty great when I step back - less than a month ago I was struggling to hand-wire a Humble Pi and wondered if a PCB might work. And here I am, PCB designed and built and debugged and working (as far as I can tell) perfectly, 100% A-OK. Brilliant.  

And note - green LEDs. St. Patrick's Day. Excellent, I would have a Guinness but I just came back from a heck of a meal out, and stout is out of the question. 

The Conductor has been sitting here for some minutes, and has successfully pumped 8.2M chars out of the PIC serial lines. It's only able to check one byte in 6 (basically, everything pumped out of PIC 0) but all those bytes have been received and checked, no garbled transmission.

I'm testing the elastic FIFO in the PIC as well, by bursting into the PIC at much higher than serial rate up to the allowable depth of the FIFO (31), then watching them trickle out at MIDI rate. Cute feature, and I'm glad it works, it will give the real code on the Conductor node much more flexibility to burst chunks of stuff into the PIC with relative impunity, and will make a big difference when only one MIDI channel is active, so the Conductor will be able to push into the single active PIC at 6x the rate it is right now.

Design Museum

Part of a short presentation I lashed up rapidly in support of my request to have a PIANA Chamber Orchestra installed in the Design Museum. They called for Pi-based projects, and I thought - "I have a Pi-based project - and it literally rocks".

And having struggled for hours with a too-slow computer and a too-demanding Final Cut Pro (damn you Apple for killing Final Cut Express!!! I LOVED that application), my favourite application du jour is now Keynote, as its ability to export video, and include video within slides, makes it the cheap man's video edit suite. Or rather, the CPU-deprived man's video edit suite. Rock on, Keynote!

Populated Conductor PCB

Next step, over the weekend, this will get tested, but right now at least the connections to 3v3, GND and to the 6 LEDs are seen to be OK. Roll on my very "Kraftwerk in my Pocket" ensemble!!

And here's a Player for good measure - but I'm still waiting for the bugfix Player PCBs to return from Seeedstudios, this is just a mockup with a known bad PCB. 

Beautiful pewter

So, along with writing apps for iPad and the Pi, and dabbling in PCB designs for the Pi, in my copious spare time (ho ho) I smelt and cast lead-free pewter. My latest design for the desktop PIANA unit now contains some cast pewter as a final, glossy finishing touch, thus moshing all my favourite activities into a single project.

The process is described here - http://www.youtube.com/watch?v=lxuA325fMVg - and for those too lazy to click through, or who just don't give a flying fig, here's a photo of something I created about 18 months ago.

The master object is designed in a CAD or DCC package (in my case, Cheetah 3D), 3D printed at Shapeways, then covered in 2 halves of silicone rubber to make a separable mould, which is a volumetric negative image of the original. Molten metal is then poured into this negative (after removal of the plastic original ...), and when it cools and the mould halves are separated, hey presto - solid, gorgeous, shiny metal. Whoo hoo!

The moulds are good for a few hundred casts, and I can't believe there are more than a hundred people on the planet who want a PIANA with a pewter front. So I shall make just the one mould. 

Here's where the pewter will go on the desktop PIANAs - 

and here's a bit of a close up - 

shot from below to reveal the toothed cylinders which I'm hoping will allow a tight, biting fit into the somewhat imprecise laser cut of the holes in the wooden base.