USB Dongle Brings Python-Controlled GPIO To The Desktop

Microcontroller dev boards are wonderfully useful items, in testament to which most of us maintain an ample collection of the things. But dragging one out to do a simple job can be a pain, what with making sure you have the whole toolchain set up to support the device, not to mention the inevitable need to solder or desolder header pins. Wouldn’t it be nice if there was a simple plug-and-play way to add a few bits of GPIO to your desktop or laptop machine?

[Nick Bild] thinks so, and came up with the USBgpio. The hardware in the dongle is pretty much what you’d expect — an Arduino Nano 33 IoT. Yes, you could just bust out a Nano and do this yourself, but [Nick] has done all the heavy lifting already. Eleven of the Nano’s IO pins plus 3.3V and ground are broken out to header pins that stick out of the 3D-printed enclosure, and the dongle is powered over the USB cable. [Nick] also built a Python library for the USBgpio, making it easy to whip up a quick program. You just import the library, define the serial port and baud rate, and the library takes care of the rest. The video below shows a quick blinkenlight test app.

Earth-shattering stuff? Perhaps not; [Nick] admits as much by noting the performance doesn’t really dazzle. But that’s hardly the point of the project, and if you need a couple of pins of IO on the desktop for a quick tactical project or some early-stage prototyping, USBgpio could be your friend. Continue reading “USB Dongle Brings Python-Controlled GPIO To The Desktop”

2024 Business Card Challenge: Adding Some Refinement To Breadboard Power Supplies

For small electronics projects, prototyping a design on a breadboard is a must to iron out kinks in the design and ensure everything works properly before a final version is created. The power supply for the breadboard is often overlooked, with newcomers to electronics sometimes using a 9V battery and regulator or a cheap USB supply to get a quick 5V source. We might eventually move on to hacking together an ATX power supply, or the more affluent among us might spring for a variable, regulated bench supply, but this power supply built specifically for breadboards might thread the needle for this use case much better than other options.

The unique supply is hosted on a small PCB with two breakout rails that connect directly to the positive and negative pins on a standard-sized breadboard. The power supply has two outputs, each of which can output up to 24V DC and both are adjustable by potentiometers. To maintain high efficiency and lower component sizes, a switch-mode design is used to provide variable DC voltage. A three-digit, seven-segment display at the top of the board keeps track of whichever output the user selects, and the supply itself can be powered by a number of inputs, including USB-C or lithium batteries.

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Multiply Your Multimeter With Relays And USB

Multimeters are a bit like potato chips: you can’t have just one. But they’re a lot more expensive than potato chips, especially the good ones, and while it’s tempting to just go get another one when you need to make multiple measurements, sometimes it’s not practical. That’s why something like this 2×4 relay-based multiplexer might be a handy addition to your bench

In this age of electronics plenty, you’d think that a simple USB relay board would be easy enough to lay hands on. But [Petteri Aimonen] had enough trouble finding a decent one that it became easier to just roll one up from scratch. His goal was to switch both the positive and negative test leads from up to four instruments to a common set of outputs, and to have two independent switching banks, for those times when four-lead measurements are needed. The choice of relay was important; [Petteri] settled on a Panasonic DPDT signal relay with low wetting current contacts and a low-current coil. The coils are driven by a TBD62783A 8-channel driver chip, while an STM32 takes care of USB duties.

The mechanical design of this multiplexer is just as slick as the electrical. [Petteri] designed the PCB to act as the cover for a standard Hammond project box, so all the traces and SMD components are mounted on the back. That just leaves the forest of banana-plug binding posts on the front, along with a couple of pushbuttons for manual input switching and nicely silkscreened labels. The multiplexer is controlled over USB using the SCPI protocol, which happily includes an instrument class for signal switchers.

We think the fit and finish on this one is fantastic, as is usual with one of [Petteri]’s builds. You’ll probably recall his calibrated current reference or his snazzy differential probe.

A Simple Hack For Running Low-Power Gear From A USB Battery Pack

We’ve all been there. You’ve cooked up some little microcontroller project, but you need to unhook it from your dev PC and go mobile. There’s just one problem — you haven’t worked up a battery solution yet. “No problem!” you exclaim. “I’ll just use a USB battery pack!” But the current draw is too low, and the pack won’t stay on. “Blast!” you exclaim, because you’ve been watching too much Family Guy or something.

[PatH] had this very problem recently, when trying to work with Meshtastic running on a RAKwireless WisBlock Base Board. You’re supposed to hook up your own rechargeable LiPo battery, but [PatH] was in a hurry. Instead, a USB battery pack was pressed into service, but it kept shutting down. The simple trick was to just add a 100-ohm resistor across the device’s battery terminals. That took the current draw from just 15 mA up to 53 mA, which was enough to keep portable USB power banks interested in staying switched on.

It’s an easy hack for an oddball problem, and it just might get you out of a bind one day. If you’ve got any nifty tricks like this up your sleeve, don’t hesitate to let us know!

Eliminate That Pesky Power-Only USB Cable With This Cable Tester

Ever wondered why your Arduino wasn’t programming, only to find out that the cable doesn’t have any data conductors? Worry not, [Spencer Maroukis] has got you covered with the USB Sleuth Cable Tester!

The cable tester is a beautiful black circular PCB, with USB ports of nearly every type on the edges. It works partially through passive detection with LEDs and otherwise through active detection of things like the orientation with an STM32 powered by a coin cell battery. But it gets better: There are disconnect switches and exposed pads to test some of the conductors with a digital multimeter!

It may not be necessary for all of us, but one thing is clear: When you needed a good USB cable, you wished you had this to actually test it. The design is open-source too, which is definitely nice if you want one for yourself.

Meanwhile this isn’t the first USB cable tester we’ve seen here.

A Basic USB-C Primer

Over the last five years or so there has been a quiet take-over of the ports on laptops, phones, and other devices, as a variety of older ports as well as the familiar USB A and micro USB sockets have been replaced by the now-ubiquitous USB-C port. It’s a connector which can do so many things, so many in fact that it bears a handy explanation. The Electromagnetic Field 2022 hacker camp has been quietly uploading videos of its talks, and a recent one has [Tyler Ward] explaining the intricacies of the interface.

Many of you will be familiar with XKCD number 927 which makes a joke about proliferating connector standards, and it’s evident that USB-C is a rare case of a connector which bucks the trend of simply making another standard, and has instead created something with which it makes sense to replace what went before. We learn about the intricacies of inter-device communications and USB-PD, and the multiple high-speed connection  lanes shoehorned into it. That one small connector can plug into a laptop and provide power, USB peripherals including network, and display, is nothing short of amazing. Take a look at the video below the break, and if you’re interested in diving deeper, have a look at our colleague [Arya Voronova]’s USB-C for hackers series.

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Getting Started With USB-C And Common Pitfalls With Charging And Data Transfer

USB-C is one of those things that generally everyone seems to agree on that it is a ‘good thing’, but is it really? In this first part of a series on USB-C, [Andreas Spiess] takes us through the theory of USB-C and USB Power Delivery (PD), as well as data transfer with USB-C cables. Even ignoring the obvious conclusion that with USB-C USB should now actually be called the ‘Universal Parallel Bus’ on account of its two pairs of differential data lines, there’s quite a bit of theory and associated implementation details involved.

The Raspberry Pi 4B's wrong USB-C CC-pin configuration is a good teaching example.
The Raspberry Pi 4B’s wrong USB-C CC-pin configuration is a good teaching example.

Starting with the USB 2.0 ‘legacy mode’ and the very boring and predictable 5 V power delivery in this mode, [Andreas] shows why you may not get any power delivered to a device with USB-C connector. Most likely the Downstream Facing Peripheral (DFP, AKA not the host) lacks the required resistors on the CC (Configuration Channel) pins, which are both what the other USB-C end uses to determine the connector orientation, as well as what type of device is connected.

This is where early Raspberry Pi 4B users for example saw themselves caught by surprise when their boards didn’t power up except with some USB cables.

The saga continues through [Andreas]’s collection of USB-C cables, as he shows that many of them lack the TX/RX pairs, and that’s before trying to figure out which cables have the e-marker chip to allow for higher voltages and currents.

On the whole we’re still excited about what USB-C brings to the table, but the sheer complexity and number of variables make that there are a myriad of ways in which something cannot work as expected. Ergo Caveat Emptor.

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