Thinking About Creating A Raspberry Pi Replacement?

October 20, 2020 by Al Williams 66 Comments

If you’ve ever wanted to try your hand at creating a Raspberry Pi-like board for yourself, you should check out [Jay Carlson’s] review of 10 different Linux-capable SoCs. Back in the 1960s, a computer was multiple refrigerator-sized boxes with thousands of interconnections and building one from scratch was only a dream for most people. Then ICs came and put all the most important parts in a little relatively inexpensive IC package and homebrew computing became much more accessible. Systems on Chip (SoC) has carried that even further, making it easier than ever to create entire systems, like the Pi and its many competitors.

Only a few years ago, making an SoC was still a big project because the vendors often didn’t want to release documentation to the public. In addition, most of the parts use ball grid array (BGA) packaging. BGA parts can be hard to work with, and require a multilayer PC board. Sure, you can’t plug these into a typical solderless breadboard. But working with these relatively large BGAs isn’t that hard and multilayer boards are now comparatively cheap. [Jay] reports that he got cheap PCBs and used a hot plate to build each board, and has some sage advice on how to do it.

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Motorized Magic Over HDMI

October 19, 2020 by Matthew Carlson 13 Comments

There is a certain warmth that seems to emanate from stereo receivers of the 70s, 80s, and 90s. Despite their large footprint and considerable heft, the soft glow of the indicator lights and solid kerthunk of switches provide a sense of coziness. When [Tom] recently swapped his receiver for a 1970s Pioneer SX-950, he found himself getting up from the couch to adjust the volume when watching TV far too often for his liking. Resolving to do something about it, he added some magic in the form of a motorized volume knob. One of the coolest tricks for stereos was to have a small motor attached to the volume knob so that it could turn the volume up or down via a remote.

The first obstacle came when [Tom] had to forgo the center tap on the potentiometer to get a motorized one. This meant the volume compensation feature would be disabled, which is but a small price to pay for convenience. After scouring the internet, he finally had the part in hand only to discover some troublesome capacitors in the way. The new pot had a rather large motor hanging off the back that the previous one didn’t have. Fortunately, there was a good bit of space between the PCB and the bottom of the chassis, so Tom was able to just flip the capacitors to the underside of the board and bend them on their sides.

The next problem to solve was how to change the volume remotely. IR was considered as well as optical cable control signals. What [Tom] did instead was to implement HDMI CEC (consumer electronics control). CEC was well documented and seemed simple to implement on an ATTINY4313 with the help of a half-H driver. The CEC protocol implemented by [Tom’s] TV seemed to be very sensitive to timing, so an external crystal was used to get more precise timing and additional handshaking was implemented to get the TV to accept the microcontroller as valid. A few fail-safes were added to make sure the motor didn’t burn out if something went wrong with the CEC protocol and a nice enclosure wrapped up the build quite nicely.

We’ve seen CEC implemented before on a PIC 18F87J50, but as a sender of CEC commands not a receiver. [Tom’s] code is available on GitHub and might prove useful if you’re looking to implement CEC on an AVR.

Thanks [Tom] for sending this one in!

TTGO ESP32 Module With Multiple Personalities

October 19, 2020 by Chris Lott 15 Comments

Volos Projects educator [Danko Bertović] had a TTGO ESP32 board looking for a project, so he implemented a surprisingly functional weather station for such a small screen. Presumably that was too boring for him, so he decided to write a version of the classic Atari game Breakout instead. [Danko] prefers using the Arduino IDE for ESP32 projects, and has made the Breakout software available as an Arduino sketch. We hope the weather station sketch will be released soon, too. The TTGO is a small ESP32 board with an ST7789V 1.14 in (29 mm) TFT color display, available from your favorite Shenzhen market supplier. This platform is perfect for all kinds of niche applications. We’d love to hear how you are using, or plan to use, these modules in your projects.

We wrote about one such project last summer, where a similar TTGO module was used to display 50-year broadcast delayed transcripts of the Apollo 11 mission. [Danko] is no stranger to Hackaday — he has made several Arduino-based calculator projects. Perhaps the most remarkable being the circuit sculpture binary number calculator from last year, another project that morphed into a computer game (Pong).

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Designing And Building A Custom Optical Fuel Sensor

October 14, 2020 by Tom Nardi 36 Comments

At some time or another, we’ve all had an idea we thought was so clever that we jumped on the Internet to see if somebody else had already come up with it. Most of the time, they have. But on the off chance that you can’t find any signs of it online, you’re left with basically two possible conclusions. Either you’re about to enter uncharted territory, or your idea is so bad that everyone has collectively dismissed it already.

Which is precisely where [James Stanley] recently found himself. He had an idea for an non-contact optical sensor which would detect when his racing mower was about to run out of gas by analyzing light passed through a clear section of fuel hose. He couldn’t find any previous DIY examples of such a device, nor did there appear to be a commercial version. But did that mean it wouldn’t work, or that nobody had ever tried before?

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An Open Source IR Gateway Based On The ESP8266

October 14, 2020 by Tom Nardi 26 Comments

The market is absolutely inundated with smart gadgets, with everything from coffee makers to TVs advertising that they support the latest and greatest in home automation platforms. Don’t worry about how many of those platforms and services will still up up and running in the next few years, the thing will probably stop working before then anyway. No sense worrying about the details in a disposable world.

Of course, not all of us are so quick to dump working hardware in the name of the latest consumer trend. Which is why [Viktor] has developed an open source infrared gateway that can connect your “dumb” devices to the latest flash in the pan backend service with nothing more than a software update. Though even modern smart TVs still include IR remotes, so there’s nothing stopping you from using it with newer gear if you don’t ~~trust~~ like the built-in implementation.

The hardware here is really quite simple, essentially boiling down to a few IR LEDs and an IR receiver hanging off the GPIO ports of an ESP8266. While the receiver isn’t strictly necessary, it does allow [Viktor] to rapidly implement new IR codes. He just points the existing remote at the board, hits a button, and the decoded command gets sent out over MQTT where he can easily snap it up.

[Viktor] has done the hard work of creating the PCB design and testing out different IR LEDs to find the ones with the best performance. But if you wanted to just throw something together in a weekend, you should be able to get his firmware running with little more than a bare ESP and a random IR LED salvaged from an old remote. But don’t be surprised if you get hooked on the concept and end up rolling your own home automation system.

New BBC Micro:bit Adds Microphone And Speaker

October 13, 2020 by Jenny List 16 Comments

There’s an old tale that TV companies only need to make a few years of kids’ TV shows, because their audience constantly grows out of their offerings and is replaced by a new set with no prior knowledge of the old shows. Whether it’s true or not is up for debate, but does the same apply to single board computers aimed at kids? The original BBC micro:bit was first announced back in 2015 and must be interesting its second generation of kids by now, but that hasn’t stopped them bringing out a second version of the little educational computer. How do you update such a simple device? Time to take a look.

Edge connector shown on the original micro:bit design

The form factor of the new board is substantially the same as its predecessor, with the same edge connector and large connection pads, and the familiar LED matrix display. The most obvious additions are a small speaker and MEMS microphone allowing kids to interact with audio in their code, but less obvious is a new touch button in the micro:bit logo. The original had it in the silk screen layer, while the new one has it as copper for a capacitive sensor.

The silicon has an upgrade too, now sporting a Nordic Semiconductor nRF52833 running at 64 MHz and sporting 512k of ROM and 128k of RAM with built-in Bluetooth Low Energy. Binaries are incompatible with the original, however all the development environments can recompile code for a new universal binary format capable of running the appropriate software for either version.

The micro:bit has been more of a hit in schools than it has in our community, perhaps because it has the misfortune to have arrived alongside so many strong competitors. However it remains a powerful contender whose easy programming alongside the power of more traditional toolchains make it a good choice for kids and grown-ups alike. We took a look at the original back in 2016, if you are interested.

Fat Bottomed-Keebs, You Make The Clackin’ World Go Round

October 9, 2020 by Kristina Panos 24 Comments

Depending on the circles you run in, it can seem like the mechanical keyboard community is all about reduced layouts, and keebs without ten-keys are about as big as it gets. But trust us, there’s plenty of love out there for the bigger ‘boards like [Ben]’s tasty fat-bottomed keyboard. Man oh man, what a delicious slab of throwback to the days when keyboards doubled as melee weapons.

More specifically, this is a 199-key modified Sun Type 5 layout. It runs on two Teensy 2.0s — one for the keyboard matrix, and one for everything else. [Ben] made the metal enclosure entirely by hand without a CNC or laser cutter. While I don’t personally care for linear switches, I have mad respect for these, which are vintage Cherry Blacks pulled from various 1980s AT/XT boards. That 10-key island on the left is dedicated to elementary macros like undo/redo, cut/copy/paste, and open/close/save.

We absolutely love the gigantic rotary encoders, which give it a bit of a boombox look. There’s even reuse involved here, because the encoder knobs are made from jam jar lids that are stuffed with homemade Sugru. [Ben] can use them to play PONG on the LCD and other games not yet implemented on the everything-else Teensy.

Here’s another Sun-inspired keeb, but this one has a reverse 10-key layout that matches the DTMF phone dial.