Propeddle, The Software Defined 6502

propeddle

When it comes to building retrocomputers, there are two schools of thought. The first is emulation, that allows for greater compatibility and ease of use, and much easier to find parts. The second requires real, vintage hardware with all the bugs and idiosyncrasies found in vintage chips. Reconciling these two ideas is hard, but the software defined Propeddle manages to do it, all while using a real 6502 CPU.

The trick here is using a Parallax Propeller for the heavy lifting of loading the ROM into RAM with an extremely clever technique using the Reset and NMI pins, generating the clock and other signals required by the 6502, and hosting the keyboard, serial, and video I/O. Already [Jac] has the Propeddle running as an Apple 1 emulator (video below), making it possible to write programs for the Propeddle in BASIC or assembly.

It’s a great design that allows for emulation of a lot of the classic 6502 computers with a real CPU, all while doing away with the cruft of expensive ACIAs and video generation hardware. Awesome work, and we can’t wait for the next version that will be dedicated to [Bill Mensch].

[Read more...]

Homemade Alarm System Doesn’t Lack Features

alarm system

To many of us, our garage (or workshop) is probably one of the most important parts of the house. If a burglar broke in, we’d likely be more worried about our tools! [Ron Czapala] decided he needed an alarm system in his garage to keep his stuff safe, so he decided to build one from scratch.

The system makes use of a Parallax 4×4 keypad membrane, a MCP23008 port expander, a Parallax Propeller, a LCD screen, and a few switches to represent future magnetic reed switches located in the door and window.

Using circular buffers, the propeller has several states for monitoring the garage.

  • Not armed — ignore all sensors
  • Armed — system will react to changes in the sensors
  • Exit delay — system has been armed, 45 second countdown has begun to allow you to exit the garage
  • Window trigger — if the window is opened, the alarm will go off immediately (siren and strobe light)
  • Door trigger — alarm will go off in 60 seconds if correct code has not been entered on the keypad

For a complete demonstration, check out the following video where [Ron] explains it all!

[Read more...]

Automated Light Painting Makes It Easy

DSC_00027

What can we say — we’re a sucker for projects that feature our favorite logo. This is the Parallax Propeller Automated Light Painting Machine  — and no, it’s not a persistence of vision setup.

[Daniel], [Nathan], and the folks over at Embedded Aesthetics are big fans of Hack a Day and are very excited to share their new project. It’s a fully automated light painting setup that features an X-axis slide, a strip of RGB LEDs, a Parallax Propeller (microcontroller), and a DSLR — all you have to do is choose an image, and press start.

They first started light painting with their LED Paint Brush, an equally awesome, but slightly less automated tool. They’ve created this one to be a bit more interactive — in fact, you can actually go on their website, upload an image, and it will paint you a picture! But… it’s not available right now.

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Once, Twice, Three Times a Nixie

Try as he might, [Localroger] can’t seem to throw away a certain board that started life in one of the first digital industrial scales, the NCI DigiFlex model 5775. He recently gave it a third career as a nixie clock with an alarm.

[Localroger] says the board dates to about 1975. It’s all TTL, no microprocessor anywhere. He was headed to the Dumpster with it in the mid-1980s, but realized that he could hack it into something useful. Since the display wasn’t multiplexed, it would be fairly easy. He used it as a BCD tester for about 10 years until the method fell out of fashion.

After a decade on the shelf, [Localroger] started off for the Dumpster once more with the board. The nixie tube display cried out for another chance to glow, so he decided to repurpose it into a remote-controlled bedside clock with an alarm. He installed a Parallax Propeller Protoboard with headers for easy removal and subsequent servicing of the 5775 board. He added a few things to the protoboard: a piezo element for the alarm, a SparkFun RTC module, an IR receiver, and vertically-oriented header so the PropPlug can be plugged in from the top. But that’s not all. [Localroger] designed a custom melamine-finished MDF enclosure and laser cut it, giving the edges a nice contrast. It’s so tough, he can put his ceramic lamp on top of it to save space on the nightstand.

Nixie tubes are becoming more scarce all the time. If you can’t find any, we humbly suggest rolling your own.

[Thanks Localroger!]

Circuit Bent Toy Keyboard is MIDI Controlled

tymkrsKeyboard
The [Tymkrs] crew has come up with a pretty neat circuit bent toy keyboard hack. It’s been a while since we’ve seen a good circuit bending hack. This project started as a way to demo the [Tymkrs] “MIDI In Me” kit. A cheap toy keyboard was sacrificed for its sound generator board. Like many cheap mass-produced toys, this board is based upon a COB (chip on board) package. The silicon die of the main ASIC is placed directly on the PCB and bonded out to pads. A round epoxy blob keeps everything protected.

The [Tymkrs] found a number of the chip’s pads were unused in their keyboard. The inputs appeared to trigger drums, possibly for use in a different toy. These inputs, coupled with the ‘demo song’ buttons turned out to be the basis of this hack. MIDI input is sent to a Parallax Propeller. The prop runs a program that will set its I/O pins based upon MIDI Note On/Off commands. The I/O pins then drive transistors which inject signals into the button inputs of the keyboard.

The [Tymkrs] even went so far as to use a voltage divider on the main clock circuit of the keyboard. Changing the main clock causes a sort of pitch bend effect often heard with circuit bent toys. As with the buttons, a MIDI signal commands the prop to enable or disable oscillator signal injection. A potentiometer is used to tweak the oscillator frequency.

[Read more...]

Rekindling Forth with a Propeller Jupiter Ace

Jupiter

The Jupiter Ace was a small membrane keyboard, cassette tape drive computer akin to the ZX Spectrum released in 1982. Priced at £90, it was a little more expensive than its home computer contemporaries, but had a very interesting feature: instead of BASIC, the Ace ran Forth. This interpreted stack-based language is far more capable than the BASIC variants found on home computers of the day, but unfortunately the Ace failed simply because Forth was so foreign to most consumers.

Not wanting to let a good idea die, [prof_braino] is bringing Forth back into the modern age. He’s using a Parallax Propeller to emulate a simple home computer running Forth. Instead of a book-sized computer, the new Propeller version runs on a single chip, with 8 CPU cores running 24 times faster than the original, with 32 times more RAM and an SD card for basically unlimited storage.

Programming a Propeller on an ARM

[Stefan] uses a small ARM-powered netbook for his development work, so when he tried to play around with the Parallax Propeller he ran into a few problems. The official tools from Parallax are Windows only, and the available 3rd party dev tools are only compiled for x86. After a lot of futzing about, [Stefan] was able to develop on his ARM netbook and wrote in to tell us how it’s done.

Luckily, Parallax released a GCC port for the Propeller, but unfortunately isn’t completely portable to ARM. The Propeller loader for this architecture ambivalent build uses a little bit of SPIN code, which can only be compiled on Intel machines.

To get around this problem, [Stefan] wrote an installer script to gather all the necessary bits of code to his computer. His ARM/Linux toolchain consists of the Propeller GCC, an open source SPIN compiler, and a Python script used to load code [Stefan] found on the Propeller forums.

Now that [Stefan] has a complete toolchain for programming the Propeller on an ARM device, it’s possible to develop for this very cool multi-core microcontroller on his netbook or even the Raspberry Pi.

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