FLEX Pager Protocol in Depth

We love pager hacks. One of our earliest head-slappers was completely reverse-engineering a restaurant pager’s protocol, only to find out that it was industry-standard POCSAG. Doh!

[Corn] apparently scratches the same itch, but in the Netherlands where the FLEX protocol is more common. In addition to walking us through all of the details of the FLEX system, he bought a FLEX pager, gutted it, and soldered on an ATMega328 board and an ESP8266. The former does the FLEX decoding, and the latter posts whatever it hears on his local network.

These days, we’re sure that you could do the same thing with a Raspberry Pi and SDR, but we love the old-school approach of buying a pager and tapping into its signals. And it makes a better stand-alone device with a lot lower power budget. If you find yourself in possession of some old POCSAG pagers, you should check out [Corn]’s previous work: an OpenWRT router that sends pages.

Designing Flat Flexible PCBs

You can find flex PCBs in just about every single piece of consumer electronics. These traces of copper laminated in sheets of Kapton are everywhere, and designing these cables, let alone manufacturing them, is a dark art for the garage electronics wizard. Having these flat flex cables and PCBs manufactured still requires some Google-fu or a contact at a fab house, but at least now designing these cables is a solved problem.

[Oli] needed a way to connect two PCBs together over a moving part. Usually this means some sort of connector or cable, but he’s developed an even better solution – flexible PCB connections. To generate these copper traces sandwiched between a few layers of Kapton, [Oli] wrote a Python script to take a set of parameters, and produces an design for Eagle that includes all the relevant bits.

Of course, with a flexible PCB layout, the question of how to get these manufactured comes up. we’ve seen a few creative people make flexible PCBs with a 3D printer and there’s been more than one Hackaday Prize project using these flex PCBs. [Oli] says any manufacturer of flexible circuits should be able to reproduce everything generated from his script without much thinking at all. All we need now is for OSH Park to invent purple Kapton.

You can grab [Oli]’s script on his GitHub.

Pulito: The LEGO Roomba

When [Dave] installed hardwood flooring in his house, he needed a solution to help automate the monotonous task of routine sweeping. Rather than go out and buy one of the many existing automated sweep robots out there, he decided to use his passion for LEGO Robotics to design and build a NXT based Swifferbot he calls Pulito. His version implements all the important features such as object avoidance using bump sensors, an IR beacon used to automatically return to the charging station, and a photoresistor to monitor the charge of the battery. [Dave] also includes a nifty LEGO sensor multiplexor, allowing him to save on I/O ports, which is almost worth sharing by itself.

Videos after the break.

Continue reading “Pulito: The LEGO Roomba”

Pinch control2: laser drawing

[atduskgreg] posted this cool looking rig.  That’s a batting glove, chopped up and equipped with a flex sensor and a pressure sensor. The end goal was to create a new method of drawing. You can see he’s interfaced with the servos decently. It seems fairly responsive and intuitive. Looking at his results though, make us wonder if all that effort was worth it. We would probably apply this rig to some kind of animatronics.

Custom flex sensors


Flex sensors, like the ones used in the Nintendo Power Glove, are generally expensive and hard to find. However, [jiovine] demonstrates that they are easy enough to make from spare parts. He sandwiched a strip of plastic from ESD bags between pieces of copper foil, and wrapped the whole thing in heat shrink tubing. The sensor is able to detect bends in either direction, unlike the original power glove sensors. His version had a nominal resistance of about 20k ohms, but by choosing a different resistive layer you could create sensors that are more or less resistive.

Related: 5-cent tilt sensor

Art From Code: Generative Graphics

[Keith Peters]’ blog Art From Code is devoted to his beautiful graphics from computer source code, also known as generative art. Although [Peters] is reluctant to reveal his source code, algorithmic graphics can be created with the help of tools like ActionScript, Flash, and Flex. There are some great tutorials that can start you on the path to making your own evocative art.

[via Neatorama]