Day: June 29, 2020

Fail Of The Week: This SD Card Won’t Slot

June 29, 2020 by 23 Comments

If you’ve got a few self-designed PCBs under your belt, you probably know the pain of missing some little detail and having to break out the bodge wires to fix it. So we feel for [Arsenio Dev], who placed an SD card slot next to an SoC, only to find that it was the wrong way round. Rather than tossing it in the bin, he decided to employ a particularly crafty set of bodge wires that curve over the board and connect to an SD card adapter on the other side.

Our attention was taken by the board itself, he’s posted little information about it and taken pains to conceal one of the pieces of text on it. Since it has an Octavo Systems BeagleBone-on-chip, a slot for a cellular modem, and a connector marked “CONNECT AERONET HERE” which we are guessing refers to the Aeronet sun photometry network, we’re guessing it might be a controller for remotely-sited nodes for that system. Either way it’s enough to have us intrigued, and we wish him every success with the next spin.

Meanwhile, this certainly isn’t the first PCB CAD fail we’ve brought you.

Updating The Language Of SPI Pin Labels To Remove Casual References To Slavery

June 29, 2020 by 287 Comments

This morning the Open Source Hardware Association (OSHWA) announced a resolution for changing the way SPI (Serial Peripheral Interface) pins are labelled on hardware and in datasheets. The protocol originally included MOSI/MISO references that stand for “Master Out, Slave In” and “Master In, Slave Out”. Some companies and individuals have stopped using these terms over the years, but an effort is being taken up to affect widespread change, lead by Nathan Seidle of Sparkfun.

The new language for SPI pin labeling recommends the use of SDO/SDI (Serial Data Out/In) for single-role hardware, and COPI/CIPO for “Controller Out, Peripheral In” and “Controller In, Peripheral Out” for devices that can be either the controller or the peripheral. The change also updates the “SS” (Slave Select) pin to use “CS” (Chip Select).

SPI is widely used in embedded system design and appears in a huge range of devices, with the pin labels published numerous times in everything from datasheets and application notes to written and video tutorials posted online. Changing the labels removes unnecessary references to slavery without affecting the technology itself. This move makes embedded engineering more inclusive, an ideal that’s easy to get behind.

[2022 Editor’s Note: The OSHWA changed its recommended naming to PICO/POCI for “Peripheral In, Controller Out” and “Peripheral Out, Controller In”. Fine by us! I’ve updated this throughout the rest of the article because it doesn’t change Mike’s original argument at all.]

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Does PHP Have A Future, Or Are Twenty Five Years Enough?

June 29, 2020 by 54 Comments

In June, 1995, Rasmus Lerdorf made an announcement on a Usenet group. You can still read it.

Today, twenty five years on, PHP is about as ubiquitous as it could possibly have become. I’d be willing to bet that for the majority of readers of this article, their first forays into web programming involved PHP.

Announcing the Personal Home Page Tools (PHP Tools) version 1.0.

These tools are a set of small tight cgi binaries written in C.

But no matter what rich history and wide userbase PHP holds, that’s no justification for its use in a landscape that is rapidly evolving. Whilst PHP will inevitably be around for years to come in existing applications, does it have a future in new sites?

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DIY Pocket MP3 Player

June 29, 2020 by 13 Comments

When [Neutrino-1] saw DFRobot’s DFPlayer module, he decided he wanted to make his own retro MP3 player. This tiny module comes packed with a ton of interesting capabilities such as EQ adjustment, volume control, and a 3 watt amplifier amongst other things. It can even play ads in between songs, should you want such a thing.

Controlling the DFPlayer module is easy using serial commands from a microcontroller, making it a convenient subsystem in bigger projects, and a potential alternative to the popular VLSI chips or the hard to come by WT2003S IC. [Neutrino-1] does a good job walking readers through the build making it fairly easy to remix, reuse, and reshare.

With the hardware sorted, all you’ve got to do is flash the firmware and load up an SD card with some MP3s. There’s even a small Python GUI to help you get your new player up and running. [Neutrino-1] also introduces users to the U8g2 display library which he says is a bit more feature-rich than the common Adafruit SSD1306 library. Great job [Neutrino-1]!

While you’re here, take a look at some of our other MP3 projects.

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An Affordable Home Made Vacuum Chamber

June 29, 2020 by 31 Comments

The term “vacuum” means many different things depending whether you are working on space equipment, scientific instruments, or even internal combustion engines. In our sphere it is so often used as a means to draw bubbles out of resin castings, for which it is a relatively easily achievable partial vacuum. It’s something [Fab] is using, in a vacuum chamber made from Plexiglass.

A simple Plexiglass box would collapse under the air pressure on its own, so to mitigate that it’s made from a piece of tube, and with an internal frame of aluminium extrusion with 3D printed joints to strengthen it from the inside. A pressure sensor allows regulation of the pump that drives the vacuum, and connections are made to the chamber using pneumatic hose connectors. It’s not immediately clear how it is sealed, whether there are nay gaskets or other sealant, or whether air pressure pushing the parts together provides enough of a seal.

We’ve featured a lot of vacuum chambers made for this purpose over the years, and we’d be interested to know what vacuum pump is being used here. If  you’re curious too and want to build your own, perhaps you could try a fridge compressor.

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