The Open, Hackable Electronic Conference Badge

Electronic conference badges have been around for at least a decade now, and they all have the same faults. They’re really only meant to be used for a few days, conference organizers and attendees expect the badge to be cheap, and because of the nature of a conference badge, the code just works, and documentation is sparse.  Surely there’s a better way.

Enter the Hackable Electronic Badge. Ever since Parallax started building electronic conference badges for DEF CON, they’ve gotten a lot of requests to build badges for other conventions. Producing tens of thousands of badges makes Parallax the go-to people for your conference badge needs, but the requests for badges are always constrained by schedules that are too short, price expectations that are too low, and volumes that are unknown.

There’s a market out there for electronic conference badges, and this is Parallax’s solution to a recurring problem. They’re building a badge for all conferences, and a platform that can be (relatively) easily modified while still retaining all its core functionality.

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Hacklet 73 – Parallax Propeller Projects

In 2006, Parallax, Inc wasn’t new to the electronics business. They’d been around since 1987. Still, for a relatively small company, jumping into custom chips is a big leap. Parallax didn’t just jump into some cookie cutter ASIC, they made their own parallel multi-core microcontroller. Designed by [Chip Gracey], the Parallax Propeller has 8 cores, called cogs. Cogs are connected to I/O pins and other resources by a hub. The Propeller saw commercial success, and continues to have a loyal following. This week’s Hacklet is about some of the best Propeller projects on!

wozWe start with retrocomputing prop star [Jac Goudsmit] and L-Star: Minimal Propeller/6502 Computer. [Jac] loves the classic 6502 processor. Inspired by [Ben Heckendorn’s] recent Apple I build, [Jac] wanted to see if he could replicate an Apple I with minimal parts. He built upon the success of his Software-Defined 6502 Computer project and created L-Star. The whole thing fits on a Propeller proto board with room to spare. The project uses a 6502, with a Propeller handling just about everything else. The system takes input from a PS-2 keyboard, and outputs via composite video, just like the original Apple I. As you can see from the photo, it’s quite capable of displaying Woz in ASCII. [Jac] has expanded the L-Star to support the Ohio Scientific C1P and CompuKit UK101, both early 6502 based computers.


bbotNext up is [Mike H] with B-BOT. B-BOT is a balancing robot. [Mike] used B-BOT to learn about designing with the Propeller and programming in SPIN, the Prop’s built-in interpreted language. While slower than assembler, SPIN was plenty fast enough to solve the classic inverted pendulum problem. B-BOT’s primary sensor is a Pololu AltIMU-10. This module contains a gyro, accelerometer, compass, and altimeter all on one tiny board. Locomotion comes in the form of two stepper motors. Command and control is via X-Bee radio modules. All the parts live on a custom PCB [Mike] milled using his CNC router.


xynq[Antti.lukats] created Soft Propeller, his entry in the 2015 Hackaday Prize. Soft Propeller doesn’t use a hardware Propeller at all. The core of the system is a Xilinx Zynq-7 chip, which contains an FPGA and a Dual Core ARM A9+ processor. Back in 2014, Parallax released the Verilog HDL code for the Propeller core. [Antti] has taken this code and ported it over the Zynq-7. With 256Kb of RAM, 16 MB of Flash and an LED, the entire system fits in a DIP package smaller than a stick of gum.


pipmanFinally, we have [Christian] with Pipman GPS Watch. There’s just something about the Pip-boy from the Fallout video game series. This Personal Information Processor (PIP) has spawned hundreds of projects from cosplayers and electronics hobbyists alike. [Christian’s] version uses a 4D systems TFT LCD to display those awesome graphics. Input comes through a 5 way navigation switch. A GPS and compass module provide all the navigation data Pipman needs. At the center of it all is a Parallax Propeller programmed in SPIN. [Christian] has a working prototype on his bench. He’s now working on modeling a 3D printed case with Blender.

There are a ton of Propeller projects on If you want to see more, check out our Propeller Project list! Did I miss your project? Don’t be shy, just drop me a message on That’s it for this week’s Hacklet, As always, see you next week. Same hack time, same hack channel, bringing you the best of!

The Self-Balancing Sideways Segway

[Jason Dorie] has been hard at work on his two-wheeled, self-balancing skateboard. He calls it the Sideway.

Similar to the Segway, it relies on the user shifting their weight to control the speed at which it will run. A Wii Nunchuk controller is used to steer, which varies each wheels output, which allows for some tight maneuvering!

Under the deck is a pair of 24V 280W (about 1/3HP each) scooter motors which are driven by two 32A Sabertooth speed controllers. They’re run off a pair of 3 cell 5Ah LiPos which get him about 40 minutes of use — not too shabby! To handle the control algorithm for the IMU, he’s using a Parallax Propeller with custom software.

To demonstrate, he takes us of a tour of one of his favorite stores — Michael’s.

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Hacklet 38 – 6502 Projects

The 6502 CPU is probably the most famous of all the 8-bit processors out there, whether in the form of bare chips for homebrew computers, or as slightly modified derivative chips found in everything from the C64, the NES, and the BBC Micro. For this edition of the Hacklet, we’re taking a look at all the 6502-based builds on

6917521396192751941There aren’t many transistors on a 6502, making it perfect for implementing on an FPGA. [Michael A. Morris] has an Arduino FPGA shield, and his soft-6502 project is called Cameleon. There’s a bunch of SPI Flash and FRAM on board, and the 128kB of (parallel) SRAM on the board is more than enough to handle any computational task you can throw at it.

Since the Cameleon is built on programmable logic, [Michael] thought it would be a good idea to put some of those unused opcodes to use. There are instructions for coprocessor support, and a bunch of instructions specifically designed to make the Forth implementation easier.

4244551421640813832Maybe programmable logic isn’t your thing, and you’d just like a simple computer like the Ohio Scientific or the Apple I. The L-Star is for you. That’s [Jac Goudsmit]’s build featuring a 6502, a Parallax Propeller, and little else.

The Parallax Propeller is a powerful (multi-core!) chip that’s easily capable of handling video out, keyboard in, and serving up the ROM and RAM of a computer. [Jac]’s build does it all beautifully, and if you’re looking for the easiest way to run code on a 6502, this is how you do it.

6502s were found in just about everything, and while poking around at the local e-waste recycler, he stumbled upon something rather interesting. The case badges screamed, “BS medical device”, but after poking around a bit, he figured out this was an MTU-130 system, a machine that was apparently the top of the line in its day.

There’s some weird stuff going on in this machine – 18-bit addressing and 80kB of RAM. So far [Eric] has managed to dump the ROM, and he’s taking a look at the floppy controller board to see if he can figure out how it’s mapped. It’s one thing to figure out what’s broken on an Apple II or C64; those are well documented machines. It’s another thing entirely to figure out a machine very few people have heard of, and we tip our hat to [Eric] and his efforts.

4000511410347834190Here’s a build that both does and doesn’t have a 6502 in it. [BladeRunner]’s SheMachine is a single board computer that has a 65c816 in it. The ‘816 is an interesting beast that operates as a standard 6502 until a bit is flipped in one of its registers. After that, it has a 24-bit address space for addressing 16 Megabytes of memory, 16-bit registers, but is still completely backwards compatible with the 6502. Yes, it does have weird interleaved address pins, but we can only imagine what the world would be like if this chip came out a few years earlier…

[BladeRunner] is designing the SheMachine with 1MB of SRAM – more than enough, really – and is mapping all the memory through a CPLD. That’s how you should do it, anyway.

Stereo Vision and Depth Mapping with Two Raspi Camera Modules

The Raspberry Pi has a port for a camera connector, allowing it to capture 1080p video and stream it to a network without having to deal with the craziness of webcams and the improbability of capturing 1080p video over USB. The Raspberry Pi compute module is a little more advanced; it breaks out two camera connectors, theoretically giving the Raspberry Pi stereo vision and depth mapping. [David Barker] put a compute module and two cameras together making this build a reality.

The use of stereo vision for computer vision and robotics research has been around much longer than other methods of depth mapping like a repurposed Kinect, but so far the hardware to do this has been a little hard to come by. You need two cameras, obviously, but the software techniques are well understood in the relevant literature.

[David] connected two cameras to a Pi compute module and implemented three different versions of the software techniques: one in Python and NumPy, running on an 3GHz x86 box, a version in C, running on x86 and the Pi’s ARM core, and another in assembler for the VideoCore on the Pi. Assembly is the way to go here – on the x86 platform, Python could do the parallax computations in 63 seconds, and C could manage it in 56 milliseconds. On the Pi, C took 1 second, and the VideoCore took 90 milliseconds. This translates to a frame rate of about 12FPS on the Pi, more than enough for some very, very interesting robotics work.

There are some better pictures of what this setup can do over on the Raspi blog. We couldn’t find a link to the software that made this possible, so if anyone has a link, drop it in the comments.

Improving the Parallax Propeller in an FPGA

The Parallax Propeller is an interesting chip that doesn’t get a lot of love, but since the entire chip was released as open source, that might be about to change: people are putting this chip inside FPGA and modifying the binaries to give the chip functions that never existed in the original.

Last August, Parallax released the source for the P8X32A, giving anyone with an FPGA board the ability to try out the Prop for their own designs. Since then, a few people have put some time in, cleaning up the files, unscrambling ROM images, fixing bugs, and all the general maintenance that an open source microcontroller core requires.

[Sylwester] has grabbed some of the experimental changes found on the Parallax forum and included them as a branch of the Propeller source. There is support for a second 32-bit port, giving the new chip 64 I/O pins, multiply instructions, video generators, hard-coded SD card libraries, and a variant called a microProp that has four cores instead of eight.

You can grab all the updated sources right here and load them up on a DE0 Nano FPGA board. If you’re exceptionally lucky and have the Altera DE2-115 dev board, you’ll also be able to run the upcoming Propeller 2.

FPGA with Open Source Propeller 1 Running Spin


Open Sourcing something doesn’t actually acquire meaning until someone actually uses what has been unleashed in the wild. We’re happy to see a working example of Propeller 1 on an FPGA dev board. That link takes you to a short description and some remapping of the pins to work with a BeMicro CV board. But you’ll want to watch the video below, or rather listen to it, for a bit more explanation of what [Sylwester] did to get this working.

You’ll remember that Parallax released the Propeller 1 as Verilog code a few weeks back. This project first loads the code onto the FPGA, then proves it works by running SIDcog, the Commodore 64 sound emulation program written in Spin for p8x32a processors.

We do find this to be an interesting first step. But we’re still waiting to see what type of hacks are made possible because of the newly available Verilog code. If you have a proof of concept working on other hardware, certainly tell us about it below. If you’ve been hacking on it and have something you want to show off, what are you waiting for?

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