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FastLED for the Apple II: Hack to the Future!

These days, I hack LEDs.  I’m the co-author (with Daniel Garcia) of the FastLED library for driving tons of high speed LED pixels and strips using microcontrollers like Arduino and Teensy.

But back in the day, I hacked a lot of Apple II.  I published a couple of shoot-em-up games (with Geoffrey Engelstein), all written in lovingly hand-crafted 6502 assembly language.

Finally I decided it was time to link the present to the past: to connect a hundred high-speed RGB LEDs to an Apple II, somehow, and ‘port’ our FastLED library to 6502 assembly language.

Well, I did it, and it works.  My new creation, “FastLED6502”, can drive a hundred 24-bit RGB pixels at more than 30 frames per second from an Apple //e :

The Details

Here are the details of “FastLED6502”:

  • “FastLED6502” is a lightweight port of FastLED’s core functions to 6502 assembly language for the Apple ][, Apple ][+, Apple //e, and Apple //gs.
  • Supports APA102 / Adafruit DotStar LED strips, as well as LPD8806 and WS2801 (though those two are not fully tested yet).
  • The LED strip is connected to the Apple II using the 16-pin DIP game port on the computer’s motherboard.  The 9-pin DB joystick/mouse port on the back of the //c, //c+, and //gs cannot be used, as it lacks the TTL digital output signals needed to drive the LED strip.
  • 24-bit FastLED Rainbow colors are included, along with FillRainbow, Random8 and a number of other useful functions from FastLED’s main library.
  • Everything had to be re-written from scratch in 6502 assembly language.  Luckily(?), I still remember how to do that.
  • The assembly code knows the binary serial protocols for the APA102 (Adafruit DotStar), LPD8806, and WS2801 LED driver chips.  Depending on which one you select, FastLED6502 transmits the LED colors in the correct protocol over the game port TTL digital output lines.
  • Considering that the Apple II sports a 1MHz 6502 so slow that even a “NOP” takestwo cycles, overall performance is pretty good: more than 30 frames per second for a 100-pixel strip.
  • Speaking of speed, or lack thereof, “three-wire” clockless LED strips such as the WS2811 NeoPixel are not supported now, nor will they ever be.  The CPU is would need to be at least 20X faster to support them, and it isn’t.  For that you want an Arduino or Teensy, and FastLED proper: http://fastled.io/
I gave the code its public debut at Veracode Hackathon 7.  (The theme was “Cozy Cabin” — I don’t usually wear plaid.)
I don't usually wear plaid.

FastLED6502 at Veracode Hackathon 7

How’s it work?

So how does this all work? Well, you connect the CLOCK and DATA_IN pins from the LED strip to a couple of pins on your Apple II’s DIP game connector port, add power, and you’re ready to go.  The Apple II’s game connector not only has inputs for joysticks, paddles, buttons, and so on, but it also has a few digital outputs — and that’s what FastLED6502 uses to deliver signals to the LED strip.  On all the 16-pin DIP Apple II game ports (except for the //gs!), there’s even one pin that delivers a super-fast digital pulse; pin 5 is the C040STROBE line, which can pulse twice as fast as the other digital outputs.  If you choose that for your CLOCK pin, the FastLED6502 code automatically shifts into high gear, and you get faster performance.   FastLED proper does this, too, in a much fancier way; it’s amusing that ‘little’ FastLED6502 does some of this, too.

The Code

The code is in the “extras” directory here (and eventually on FastLED’s main branch, but not yet)
Here’s the FastLED6502.s65 source code itself:
https://github.com/FastLED/FastLED/blob/FastLED3.1/extras/FastLED6502.s65And here’s the RainbowDemo.s65, as shown in video:
https://github.com/FastLED/FastLED/blob/FastLED3.1/extras/RainbowDemo.s65

This is Crazy

Overall, this bit of code is completely nuts, and we don’t expect anyone to use it.  At all.  Ever.  Accordingly, we’re not going to really support it, either.  At all.  Ever.  It was a labor of love and a creation of pure modern retrocomputing insanity.  But here it is, in all it’s insane glory, “FastLED6502”.
And now, if you cut me, I’ll bleed 16,777,216 colors at thirty frames a second.
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Lanyard-mountable LED throwies

At the last “HacKidThon”, we showed a passel of kids how to make LED “throwies”. Each one is a nothing more than an LED, a coin cell battery, and a magnet so the contraption can stick to metal surfaces, walls and buildings, and hang there glowing.

This week, someone asked me if we could modify the classic design somehow so that the LEDs could be attached to lanyards, instead of magnets. We wanted it to be as cheap and easy as the rest of the “throwie” recipe.

A little brainstorming with Eleanor, and we came up with this: plastic-coated paperclips!

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The paperclips actually help hold the LED leads in place; we put tape around them as usual, though that’s not shown in the picture. The plastic coating keeps the paperclip from shorting out the positive and negative battery terminals.

The coated paperclips cost less than a penny apiece, and come in colors that match the LEDs. Victory!


Easter Egg Hunt Rules, 2014.

We love doing Easter egg hunts.  But as the girls get faster, smarter, and more wily, merely finding the eggs is no longer challenge enough.  I’ve gotta slow ’em down somehow, and this is how I do it: each girl gets an empty basket (I use traditional Jack-O-Lantern baskets), and sheet of instructions helping her know which eggs are for her, and which are for her step-sister.  Each year, the instructions require more careful reading and invoke increasingly complicated rules.

New this year: the contents of two of the eggs altered the interpretation of rules, retroactively. This fact itself was part of the published rules… this time.

 


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The best part was watching the girls excitedly pounce as they found the first eggs, and then stall completely as they had to stop and puzzle out exactly who’s egg it actually was that they’d just found.

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-Mark

 


 

P.S. Here are the previous year’s Egg Hunt Rules (2013):

Easter2013


Fire2012: an open source fire simulation for Arduino and LEDs

I’ve built and programmed a couple of different ‘fire’ simulations for Arduino and LEDs, and I’ve had numerous requests over the years to share the source code.  I’ve always been happy to share my work; the holdup has been that before I share my code for the world to peer at, I like to clean it up a little.  I like to give the code a clean shave and scrub under its fingernails before it steps out onto the wide open Internet where it might have an audience with Her Royal Majesty, The Queen of England.  It could happen.

Anyway, I finally cleaned up the code for one of my simplest and most legible ‘fire’ simulations, and I give it to you, your Majesty, and everyone else, too. Here’s a video of the code in action on a 30-pixel strip of WS2812B LEDs (or maybe WS2811) and an Arduino.  Source code link is below the video.

Full source code is here: http://pastebin.com/xYEpxqgq  The simulation itself is only about 25 or 30 lines of code.  It uses our (open source) FastLED library to drive the LEDs.

Discussion about the code and how to port it and use it are here on the FastLED discussion group on G+ https://plus.google.com/112916219338292742137/posts/BZhXE4cqEN4

Enjoy!

-Mark

 


If I’m confused, it must be playtime.

Some things we try because we have a clear idea where we want to be and a clear idea how to get there.

Some things we try because we’re suddenly shocked to find that the heretofore completely impossible has suddenly and surprisingly come within practical reach.

And some things we try just to play, and to explore what if. We start with our heads full of simple ideas that turn out to be wrong, and we awkwardly replace them in torn out bunches with new confused half-understandings that, later, will let us reach something wholly unexpected.

I’m not sure which of these things in doing here, which means it’s probably that last one.

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Hoop skirt — made with real hoops!

Eleanor and I spent this weekend working on her Halloween costume.  Part of what she planned was a ‘hoop skirt’, but as you can imagine no commercially available hoop skirt met her exacting standards of design and quality — and also my exacting budgetary requirements.  Naturally, we decided to take the DIY route!  And, we pondered, what goes into a hoop skirt? HOOPS, obviously!

We picked up a used dress at The Garment District (our local vintage/costume/cheapo clothing mecca), a set of three hula-hoops, and some leopard-print duct tape.  The smallest hula hoop became the bottom (largest) hoop for the skirt; the other two had to be dramatically resized smaller (via pliers, dremel, duct tape).  We started construction from the waist down, with a nylon web belt with a parachute snap buckle.  From there, we hung each hoop with repositionable blue painters tape, and balanced each one until it was level.  Then Eleanor secured each hoop in place at the right height with duct tape.

And presto! A hoop skirt made with real hoops! (and duct tape, of course!)

Hoop skirt -- made with real hoops!


“Firelight” Lantern

This past January (2013), I created “Firelight”, a lantern that shines with the light of a simulated fire.

The lantern contains over a hundred LEDs, a microcontroller, a battery pack, and custom software.  The software monitors the remaining power in the batteries, and as the voltage slowly runs down, the flames burn lower, finally dying into embers as the batteries die.

I presented the Firelight lantern at the Veracode winter Hackathon, where I lit it, and then gently blew on the coals to kindle a flame.  I’ve had a few requests to build more of these lanterns for other people, and I’m considering it, but haven’t made a decision yet.  More pictures are here.

-Mark