Reverse Engineering Your Own Bluetooth Audio Module

There was a time when we would start our electronic projects with integrated circuits and other components, mounted on stripboard, or maybe on a custom PCB. This is still the case for many devices, but it has become increasingly common for an inexpensive ready-built module to be treated as a component where once it would have been a project in its own right. We’re pleased then to see the work of [ElectroBoy], who has combined something of both approaches by reverse engineering the pinout of a Chinese Bluetooth audio chip with minimal datasheet, and making his own take on an off-the-shelf Bluetooth audio module.

The JL_AC6939B comes in an SOIC16 package and requires a minimum number of components. The PCB is therefore a relatively simple proposition and indeed he’s fitted all parts and traces on one side with the other being a copper ground plane. It’s dangerous to assume that’s all there is to a board like this one though, because many an engineer has come unstuck trying to design a PCB antenna. We’d hazard a guess that the antenna here is simply a wavy PCB line rather than an antenna with a known impedance and bandwidth, at the very least it looks to have much thicker traces than the one it’s copying.

It’s possible that it’s not really worth the effort of making a module that can be bought for relative pennies ready-made, but to dismiss it is to miss the point. We make things because we can, and not merely because we should.

Simple Dev Board Module Socket

When you’re building a quick prototype or a one-off project it’s nice to be able to securely mount the various modules and development boards. Sometimes these boards have mounting holes, but often they don’t. As an example from the latter category, digital music instrument maker and performer [DIYDSP] shows us how to build a simple socket to mount an STM32 Nucleo-32 module.

The socket is built on a standard pad-per-hole piece of vector board cut to the desired size. Pairs of female pin header strips are soldered down to the board. The inner pair of headers is for the module, the outer pair is for your interconnections. The headers are connected up with short solder bridges, and [DIYDSP] recommends you extend the outer pair several pins longer than necessary. These extras can be used for additional power or ground points, or on some boards they could connect to the debug header pins. He prefers to use female sockets because that lessens the odds that an accidentally bent pin will short something out.

Final step is to drill your mounting holes in the desired location, and no more development boards free-floating and held up only by wires. Do you have any tips for mounting these kinds of modules, either individually as shown here or onto PCBs? Let us know in the comments.

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Forth Module The Size Of A Stick Of Gum

Australian engineer [John Catsoulis] developed a small module called the Scamp2 dedicated to running Forth. The focus of his Udamonic project was not only to highlight Forth, but to make a module which was easy to use and doesn’t require any IDE on your computer. According to the website, these modules have found their niche in education as well as rapid prototyping for product development. His site has some good resources, including several Scamp/Forth example applications such as a model train controller or adding a real-time clock module.

The core of the module is a Microchip PIC24F64GB202 MCU with 64K Flash and 8K RAM. Of this, Forth takes up only 20K of Flash and 2K of RAM. [John] is using FlashForth, a version of Forth which came from [Mikael Nordman] at the University of Queensland almost ten years ago. FlashForth has been implemented on a wide variety of PIC and AVR ATmega processors and has apparently developed quite a following in Australia and elsewhere.

We estimate from the photo that the Scamp is about 80 mm long, just slightly longer than a standard piece of MIL-A-A-20175A Type II chewing gum ( 73 mm ). You can use it as-is, or with the header pins installed, the Scamp can be plugged into a breadboard for easy hacking. Regarding the interfacing of Scamp to other equipment, [John] says “Writing software to use other hardware is very easy, and fun.” We like his attitude.

Here is some more information from his project page, and he also has a Tindie site. If you want a good overview of using Forth in embedded systems, check out Forth: The Hacker’s Language by our own Forth-guru [Elliot Williams]. Thanks to [Stephen Walters] for sending in the tip.

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DIY CircuitPython Brain Snakes Into Small Spaces

Whether you’re new to electronics and programming, or you were bit-banging bare metal long before hair metal, CircuitPython is a great tool for getting a project up and working without all the fuss. The boards show up as mass storage devices, and programming consists of editing the Python file and saving it back to the board.

The only hard part about CircuitPython is trying to cram those official boards into small projects. [Kevin Neubauer] got tired of making his own board every time and came up with a slim system-on-module that has all the core functionality of CircuitPython. CircuitBrains Deluxe has regular holes for using headers, but also has castellated pads so he can solder these modules directly to a larger project PCB. [Kevin] says these are still in the testing and cost-optimization phase, but we would totally buy a few of them.

[Kevin] probably has a programming method for this module in mind already. But if you find yourself mystified by castellated pads, take a look at this pogo pin programmer built for ESP8266s. If your problem is pitch-related, maybe you can save the day with a breakout board.

Thanks to [Drew Fustini] for the tip!

Snoopy Come Home: The Search For Apollo 10

When it comes to the quest for artifacts from the Space Race of the 1960s, few items are more sought after than flown hardware. Oh sure, there have been stories of small samples of the 382 kg of moon rocks and dust that were returned at the cost of something like $25 billion making it into the hands of private collectors, and chunks of the moon may be the ultimate collector’s item, but really, at the end of the day it’s just rock and dust. The serious space junkie wants hardware – the actual pieces of human engineering that helped bring an epic adventure to fruition, and the closer to the moon the artifact got, the more desirable it is.

Sadly, of the 3,000,000 kg launch weight of a Saturn V rocket, only the 5,600 kg command module ever returned to Earth intact. The rest was left along the way, mostly either burned up in the atmosphere or left on the surface of the Moon. While some of these artifacts are recoverable – Jeff Bezos himself devoted a portion of his sizable fortune to salvage one of the 65 F1 engines that were deposited into the Atlantic ocean – those left on the Moon are, for now, unrecoverable, and in most cases they are twisted heaps of wreckage that was intentionally crashed into the lunar surface.

But at least one artifact escaped this ignominious fate, silently orbiting the sun for the last 50 years. This lonely outpost of the space program, the ascent stage from the Apollo 10 Lunar Module, appears to have been located by a team of amateur astronomers, and if indeed the spacecraft, dubbed “Snoopy” by its crew, is still out there, it raises the intriguing possibility of scoring the ultimate Apollo artifact by recovering it and bringing it back home.

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Raspberry Pi Zero Stepper Driver, First Of Many Modules

The Raspberry Pi in general (and the Zero W model in particular) are wonderful pieces of hardware, but they’re not entirely plug-and-play when it comes to embedded applications. The user is on the hook for things like providing a regulated power source, an OS, and being mindful of proper shutdown and ESD precautions. Still, the capabilities make it worth considering and [Alpha le ciel] has a project to make implementation easier with the Raspberry Pi Zero W Stepper Motor Module, which is itself part of a larger project plan to make the Pi Zero W into a robust building block for robotic and CNC applications.

[Alpha le ciel] is building this stepper motor module as the first of many Raspberry Pi hats meant to provide the Raspi with the hardware for robotics applications. This module, in particular, features two A4988 stepper motor drivers, a connector for a power supply or battery providing 7-20V, and a buck converter to bring that power down to the 5V needed by the Pi itself. All the relevant pins are broken out onto the Pi’s GPIO header, making this module the simplest way possible to add a pair of motors to a Pi. What does that mean? Printers or self-balancing robots, really whatever you want.

A stepper driver that conforms to the footprint of the Pi Zero is a good start, and the larger concept of creating additional modules is a worthy entry to the Hackaday Prize.

Debouncing The Old-Fashioned Way

If you were given the task of designing a computer at a time when computers weren’t really even a thing, how would you start? How would you take a collection of vacuum tubes, passive components, and a precious few germanium diodes and engineer something to sell to customers looking for an “electronic brain”?

Where there’s a paycheck, there’s a way, and computer archeologist [Ken Shirriff] laid his hands on some old IBM hardware that tells us a lot about how engineers thought in the earliest days of the computer industry. The gear is a pluggable module from IBM, one of hundreds that once went into their Model 705 computer from the mid-1950s. The particular module [Ken] has is a 5-channel contact debouncer, or in Big Blue’s mid-century parlance, a “Contact-Operated Trigger.” It was used to debounce five of the many, many mechanical contacts in the machine, both buttons and relays, and used eight dual triode tubes to do it. Other modules with the exact same footprint formed the flip-flops, inverters, buffers and clocks needed to build a computer.

[Ken]’s analysis of the debouncer is a fascinating look at what was possible with the technology of the day, and the fact that it led to a standardized framework for generic modules that were actually hot-swappable with what essentially was a zero insertion force plug was quite a feat of engineering. And as a bonus, [Ken] and friends actually got the module up in running in the video after the break.

Jonesing for more retro-computer pluggable goodness? Check out this reproduction IBM flip-flop module from the 1940s.

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