Snack 'N' Hack

Logician Toy Program
February 16, 2011, 3:37 am
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I am building a “Logic Calculator” that will output either truth-tables or truth values depending on the amount of input the user assigns to a variable.  I’ve done a mock-up of the GUI in Visual Studio and I’ll begin doing some of the coding soon.

My background is a shot of the Appalachian mountains in the fall.

80’s Player Visualization
January 31, 2011, 1:49 am
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Enter the 80’s
January 31, 2011, 1:06 am
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I’ve had an idea to build an 80’s music player for a long time, but I’ve struggled with the exact meaning of that.  Originally, I wanted to build a digital music player only using 80’s parts, but memory was a hugely limiting factor of the 80’s (and likely why digital music players didn’t emerge until the CD).  Magnetic tapes can’t (to my knowledge) be pushed fast enough reliably to stream digital music – and they offer better quality as analog devices anyway.  So came the compromise:

I’m pursuing the project using an SD card, but this could be done with ROM chips and a switching chip (like the late-released Nintendo games with Memory Mappers).  The fact that it is POSSIBLE to do it in an authentic way has allowed me to pursue the project (maybe one day I’ll produce cartridges to prove that it is possible).

I’ve also begun to use fritzing – and I generally like it – though the parts selection is a little limited.

This is an obviously unfinished fritzing picture of the project.  I didn’t make the huge SD card, but I appreciate the guy that did: Commenter 37

The chip on the breadboard is an AY-3-8910 programmable sound generator.  This type of chip was very popular in the 80s because they required less memory to operate (in all senses) than DAC chips. This particular chip was used in the Apple II sound card MockingBoard. Eventually, I plan on using the work of the MSX crew with their Viterbi algorithm to have a nice digital format.  A secondary goal is to build this in an Atari Cartridge and have a sub-routine that provides visualizations on a real ATARI.

The TigerNome project is on hold indefinitely.  I recently realized that the pad-based touchscreens associated with Android offer a really good platform for a lot of my input ideas, and I don’t have to buy additional hardware.

Wanna Know all those Midi Messages?
November 29, 2010, 9:33 pm
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Go Here to Check out Midi Messages

A great link:
November 29, 2010, 9:13 pm
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Lame Post, Great Link.

TigerNome Update – Lights Out Pinouts
September 7, 2010, 1:53 pm
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I have been hacking the light’s out big brother, “Henry” that I picked up from a thrift store yesterday and I’ve figured out how to map out the switches.

I’m going to assume that you have a multimeter, and if you don’t, go get one.

I drew a full schematic of the way the LEDs are driven.  Common Anode (whichever Pin I identified as +).  The two connections that must be driven low allow the transistor to act as a switch and move the current from + to your LED.  Still not sure what the voltage limit for those LEDs is, but I’m going to guess somewhere around 9V.  A strong 5V source lights them up nicely.

Now – To map out the buttons.

The buttons are also arranged in a matrix.  Figuring out the layout is pretty straight forward:  Multimeter in continuity mode, one end on the pin you’re testing, then test for continuity on the button pads.  You have to watch your meter because sometimes there’s not enough connection to get a beep, but enough to see the numbers change.  Most of the pads also have a test pin.

That’s how I mapped out the “Henry” game.  Haven’t set up a micro-controller for scanning the matrix yet, but it’s a clear matrix that mostly makes sense.

If I can find my lights out, or get another one, I’ll do the same mapping for the button pad.


PS – post pictures / Schematics some time this week.

Back to Work!
August 9, 2010, 3:40 pm
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I haven’t yet fallen into a habit with the blog, or with my hacking for that matter.  The Miss and I moved to Athens, GA recently, but it gave me a great opportunity to set up a new lab.  Added Sparkfun’s copy of the hakko 936 to my collection of tools.  I haven’t gotten used to soldering at a higher temperature yet, and I may have ruined my tip on some plastic while desoldering some Super Nintendo connectors, but I’m pretty happy about it.  It even has a status LED.  We all love LEDs.

UPDATE: I’m working on a new PAID project for a pedal design firm in Asheville, NC.  It’s basically a PIC project set up for audio processing.  Seriously considering moving to the 18 series with an eeprom for this project.

Keep on hacking!

June 23, 2010, 6:13 pm
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The more-or-less maximum frequency of a standard 22 fret guitar is around 1,100 HZ.

Therefore, for Analog to Digital conversion, a low-pass filter of most signals above say 1,300 HZ would be essential to reducing random artifacts and noise.  The Biscuit and Colin’s Effect Pedal prove that very standard, low end PICs can be used for high-quality 8-bit audio applications.  Both also employ low-pass filters at the beginning of their signal chains to reduce random noise and artifacts.

In the following diagram two op-amps are combined to form a 4-pole Butterworth low pass filter with a cutoff frequency of 22-kHz.  This is NOT my work, it is from another PIC guitar effects pedal.

To get accurate A/D conversion from audio, it is ESSENTIAL that some sort of input buffering and filtering be performed.  For me, this is one of the hardest parts of the process, but I plan on having the filter built very soon.

Just another note: Guitar harmonics above the sampling rate will cause noise in the signal.  Therefore, some harmonic loss is an inherent part of this process.  You wouldn’t be building a bit-crusher if you were looking for audio purity.

The Hack is Back!
March 13, 2010, 2:45 am
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After a long and hard winter the hack is back.  I’ve got a full-time relatively high paying job which has its pros and cons.

Pro: I have enough money to actually buy materials for my hacking addiction.

Con: I don’t have as much time as I did to actually hack (though I’m basically low-level hacking all day at work).

I am returning to the Tigernome project.  I found another Lights Out game at Goodwill for $2.50, so I am taking another crack at the hack.  I have a better screw-driver this time, so I didn’t make the mistake of damaging the board.  Also, I know more about the circuit, so I won’t be separating the boards.  All of the transistors on the board are necessary for correctly amplifying and switching the signals from the membrane switches.

Well! It feels good to be back on top.


C-64 Mobile Internet Device (no, it’s not Ben Heck’s laptop).

Blinking Driven Directly from Microcontroller
November 30, 2009, 7:54 pm
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I have spent the last two weeks scratching my head and building Transistor based digital switching devices.  Every experiment ended in what might be called “failure,” but today the lights are blinking.  A few days ago I started to doubt the code produced by Matrix Multimedia’s Flowcode for PIC Micro – and for good reason.  When I read the code I realized that the way they had their blink LED routines written would not work for Port A of the Pic 16f887 – which is an analog port that requires special setup.

Once I discovered their error I began to write my own code and had a few more problems getting MPLAB to export correctly to my programmer utility.  I recently switched my development environment and admittedly I’m getting used to some of the quirks.

Friday I wrote some simple Assembly for the PIC that should make an LED light – and voila! it did (after a bit of tweaking as always).  Also, I found a great resource.  Pic List has a delay code generator that makes nice concise loops to any exact interval.  Yes, we can all write our own delay loops, but having one at an odd interval on demand is nice.  Yes, I used the code generator to produce a 1 second delay.  Yes, I am lazy.

As you can’t see from the picture – the Microcontroller is directly driving the LED Matrix (which as you remember must be brought to ground).  No problems yet and it’s been blinking those 4 LEDs for about an hour.

Yippee Yay Hooray!