PyramidHead

Oct 17

C64 Raspberry Pi Case

I’ve been using Blender 3D for a while and have recently bought a 3D printer.

This little Raspberry Pi case was my first experience with trying to design something useful - It’s easy to make something which looks fine in Blender but doesn’t fit well together in the real world.

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Someone on Twitter asked if I had any additional information, so I’m going to describe the steps from printer to the finished article here.

I might write more in future on the earlier ‘iterative design’ stages, but skipping all that for now, here’s how the current version looks in Blender:

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… And here’s how that looks while printing:

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I use a Wanhao Duplicator 4S printer. It’s a pretty solid clone of the Makerbot Dual. It has two extruders (print heads) and can print in two materials at the same time, but that feature isn’t used here.

This case comprises three parts, which are printed separately (Base, Lid, Keyboard).

There are various tips, techniques and cheats for getting things to actually print well with these FFF printers. “Simplify3D” is my tool of choice for converting the .STL exported from Blender into the instructions that the printer can use.

If all goes well when printing is complete you’ll end up with something looking like this:

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In this image you can see the support structures which provide something for the overhanging areas to print on top of. All of this has to be manually removed.

If you’re wondering how the parts look ‘off the printer’ with no further processing - There are a few rough edges but they actually don’t look bad at all:

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It takes around 14 hours of printer time to print these three parts.

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There’s a slightly roughness where the layers are visible if you look very, very close, but I could live with one of these printed in the right colour of plastic.

That said, with a bit of Filler Primer, wet & dry sandpaper and manual labour, we can do better:

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As you can see with a bit of effort, the layers aren’t really visible at all any more.

At the top you can see the raw print with one coat of filler primer applied. Then we sand, spray again, sand again, spray again, sand again… And finally add a coat of grey primer, which we need because our C64(ish) final paint colour is closer to grey than to the filler-primer-orange.

With one final coat of paint, we have - Another mini C64! The top one is the new one. It’s an improvement on the first attempt for various reasons (More solid base, resists warping and makes the clip force stronger).

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This one just needs logo stickers and it’s done.

Sep 10

ATARI Lynx II / Raspberry Pi - Part 1

I recently uploaded a video of my attempts to resurrect a dead Lynx II using a Raspberry Pi. You can find that here. Today I had a question on Twitter (from @pzkfw5) asking for more information & I guess it makes sense to answer here in case there’s any further interest.

I’ll have to split this over a few posts, starting with “What is the Lynx and what am I trying to do?”. Later I’ll move on to:

It’s all a work in progress. If you take a close look at the video you’ll see that most of the components are floating around on my desk rather than actually in the Lynx right now. I don’t yet know if it’ll ever be truly finished.

1. What is the Atari Lynx?

The Lynx was a battery powered, 8/16 bit games console with a colour LCD screen. It launched in 1989, where it was competing with the Nintendo Gameboy and later the Sega Game Gear.

http://en.wikipedia.org/wiki/Atari_Lynx

It was pretty advanced for its time. Back then the Gameboy was monochrome & your home computer would’ve been 16-bit at best. If you had a laptop at all it would’ve also been black & white even if you’d paid £3000+ for it.

My Lynx (technically a Lynx II) has been dead for 20 years.

2. What was my plan?

Like a lot of people. I bought a Raspberry Pi without much of a plan in mind for what I’d do with it. But I have a loft full of old computer ‘junk’, went hunting for something to put the R-Pi into and found this in a bag.

I opened it up, took the components out & poked around a bit. This is what the constituent parts of a Lynx II look like…

The upper & lower plastic casing

There’s a flex PCB mounted to the upper case which drives the buttons/DPAD. The cable dangling from this PCB (visible just below the orange Atari logo) can be connected to the Raspberry Pi GPIO pins to make all those things work under Linux. I found schematics online for the Lynx but still used a multimeter to double check which wires went where.

In the pic above, the connecting cable actually is connected to a socket, which itself is soldered to a strip plug that I can connect to the R-Pi. It’s not very pretty at the moment but it works.

Lynx II Motherboard

I’ve de-soldered & removed the keypad connector on this motherboard - Somewhat brutally. The quality of this desoldering will probably make hardware people cry.

LCD Screen & Backlight

The Lynx screen was impressive in its day. But now, the 160 x 102 resolution & HUGE power hungry backlight mean that I probably wouldn’t want to retain it even if I could.

3. Will it fit?

The case is physically big enough to easily contain a Raspberry Pi, but by the time I’ve added a screen, batteries, etc, it’ll be very tight, I think. 

Here’s how some of my replacement components stack up against the originals

Again, the Lynx II motherboard was every bit as impressive as the R-Pi in its day. VLSI means ‘Very Large Scale Integration’. Basically, miniaturisation through combining what would previously have been separate chips onto one bigger chip to save cost and space. The System-on-chip at the heart of the Raspberry Pi takes this to an extreme which wasn’t possible in 1989.

Here you can see the original screen (left) vs the new one (right). I found the new 3.5” screen on eBay & it’s a VGA (640 x 480) composite device.

As luck would have it, the new screen fits perfectly inside the plastic case ‘window’. There’s some cropping of top/bottom of screen but that’s fine for my purposes.

This pic shows the relative thickness of old and new screens. The bulge in the old screen is for the CCFL (flourescent tube) and the mirror to reflect all of the light back through the screen. The new screen is probably LED backlit, but could have a tiny CCFL tube, I haven’t poked around. Even with its controller PCB (blue) it’s maybe 1/3rd of the original screen thickness.

The only other thing missing is power. The Lynx originally ran on AAs but I’d rather see if I can fit modern LIPO batteries in there somehow. I have a couple of ‘mobile USB charger’ devices that I’m experimenting with.

Unfortunately my choice of screen complicates matters slightly - It expects a 12v supply while the Raspberry Pi needs 5v. So, eBay to the rescue again: I found a cheap step-up converter which will take a 5v input and supply 12v to power the screen.

It’s a very simple device (left) with a pin for ground, a pin for input (5v) and a pin for output (12v).

However, a mobile USB charger won’t provide enough current to power both the raspberry pi and the screen. So now I need either two batteries or one with two regulated outputs (which I have… More on that later).

I reckon that’s enough for a first post… Any comments/questions please let me know.

Feb 02

Keyrah! Wait, what?

So, what’s this?

If you answered ‘Commodore 64’, you’re close, but wrong!

This arrived in the post this morning:

The USB lead is a subtle clue as to what it really is…

It’s a handy device you can buy which converts most Commodore 8-bit computers into fully functioning USB keyboards. It even has two 9-pin joystick ports!

I have a few (*cough*) dead commodore computers & planned to turn one into a HTPC at some point, so it didn’t take long to open that up & screw this in.

Put it back together and it does exactly what it says on the tin: The donor C64 is now a USB keyboard which works anywhere that you can normally plug in a USB keyboard. In these pics, it’s connected to a Linux box where most of my emulator games live.

The joystick ports work by simulating keys, which means they work great with emulators (where most people will want to use these things). I guess they’ll also work with most PC/MAC games that work with keyboard input too, if you’re tempted to try your old joysticks with new games.

The switch alternates between two keyboard/joystick modes. One setting is meant for people who want to use their Commodore as a regular(ish) PC keyboard, while the other is meant for emulators.

I’m very happy with the quality of it. If you’re tempted, you can find your own here: http://www.vesalia.de/e_keyrah.htm

… But of course you’ll have to supply your own C64/C16/Vic20/C128/Plus4.