USB Adaptor Isolates Multiple Serial Interfaces

October 13, 2020 by Chris Lott 34 Comments

You need a Swiss Army knife of serial communications? Ollie is a compact isolated USB adaptor that provides USB, CAN bus, and two UARTs at logic, RS-232, and RS-485 signaling levels, as well as an isolated power supply. [Slimelec] has managed to squeeze all this into a package the size of a harmonica. We like the technique of making the enclosure from PCB material, complete with clearly labeled switch, LED and connector pinout names.

So far, only the compiled firmware is available for this project, but hardware files, and presumably the source code and documentation, are coming soon.

The central themes here are isolation and flexibility. We can’t find the isolation voltage in the project specifications, but the CANable project on which this adaptor is based provides 2.5 kV galvanic isolation. A single isolated USB interface is also provided over a standard Type A connector. The four-wire logic-level UART signals are available on a 2 x 7 box header, and are voltage selectable. The RS-232, RS-485, and CAN signals are on an 8-pin pluggable screw terminal block, or you can use a DB9 connector with a pluggable adaptor board.

Whether you need a troubleshooting aid for field testing, are using CAN bus on your projects, or just want to isolate your expensive computer from sketchy prototype hardware, have a look at this project.

Vizy “AI Camera” Wants To Make Machine Vision Less Complex

October 4, 2020 by Donald Papp 9 Comments

Vizy, a new machine vision camera from Charmed Labs, has blown through their crowdfunding goal on the promise of making machine vision projects both easier and simpler to deploy. The camera, which starts around $250, integrates a Raspberry Pi 4 with built-in power and shutdown management, and comes with a variety of pre-installed applications so one can dive right in.

The Sony IMX477 camera sensor is the same one found in the Raspberry Pi high quality camera, and supports capture rates of up to 300 frames per second (under the right conditions, anyway.) Unlike the usual situation faced by most people when a Raspberry Pi is involved, there’s no need to worry about adding a real-time clock, enclosure, or ensuring shutdowns happen properly; it’s all taken care of.

‘Birdfeeder’ application can automatically identify and upload images of visitors.

Charmed Labs are the same folks behind the Pixy and Pixy 2 cameras, and Vizy goes further in the sense that everything required for a machine vision project has been put onboard and made easy to use and deploy, even the vision processing functions work locally and have no need for a wireless data connection (though one is needed for things like automatic uploading or sharing.) For outdoor or remote applications, there’s a weatherproof enclosure option, and wireless connectivity in areas with no WiFi can be obtained by plugging in a USB cellular modem.

A few of the more hacker-friendly hardware features are things like a high-current I/O header and support for both C/CS and M12 lenses for maximum flexibility. The IR filter can also be enabled or disabled via software, so no more swapping camera modules for ones with the IR filter removed. On the software side, applications are all written in Python and use open software like Tensorflow and OpenCV for processing.

The feature list looks good, but Vizy also seems to have a clear focus. It looks best aimed at enabling projects with the following structure:

Detect Things (people, animals, cars, text, insects, and more) and/or Measure Things (size, speed, duration, color, count, angle, brightness, etc.)

Perform an Action (for example, push a notification or enable a high-current I/O) and/or Record (save images, video, or other data locally or remotely.)

The Motionscope application tracking balls on a pool table. (Click to enlarge)

A good example of this structure is the Birdfeeder application which comes pre-installed. With the camera pointed toward a birdfeeder, animals coming for a snack are detected. If the visitor is a bird, Vizy identifies the species and uploads an image. If the animal is not a bird (for example, a squirrel) then Vizy can detect that as well and, using the I/O header, could briefly turn on a sprinkler to repel the hungry party-crasher. A sample Birdfeeder photo stream is here on Google Photos.

Motionscope is a more unusual but very interesting-looking application, and its purpose is to capture moving objects and measure the position, velocity, and acceleration of each. A picture does a far better job of explaining what Motionscope does, so here is a screenshot of the results of watching some billiard balls and showing what it can do.

Bunnie’s Betrusted Makes First Appearance As Mobile, FPGA-Based SoC Development Kit

September 29, 2020 by Maya Posch 18 Comments

Recently, [Bunnie Huang] announced his Precursor project: a spiffy-looking case housing a PCB with two FPGAs, a display, battery and integrated keyboard. For those who have seen [bunnie]’s talk at 36C3 last year, the photos may look very familiar, as it is essentially the same hardware as the ‘Betrusted’ project is intended to use. This also explains the name, with this development kit being a ‘precursor’ to the Betrusted product.

In short, it’s a maximally open, verifiable, and trustworthy device. Even the processor is instantiated on an FPGA so you know what’s going on inside the silicon.

He has set up a Crowd Supply page for the Precursor project, which provides more details. The board features a Xilinx Spartan 7 (XC7S50) and Lattice iCE40UP5K FPGA, 16 MB SRAM, 128 MB Flash, integrated WiFi (Silicon Labs WF200-based), a physical keyboard and 1100 mAh Lio-Ion battery. The display is a 200 ppi monochrome 336 x 536 px unit, with both the display and keyboard backlit.

At this point [bunnie] is still looking at how much interest there will be for Precursor if a campaign goes live. Regardless of whether one has any interest in the anti-tamper and security features, depending on the price it might be a nice, integrated platform to tinker with.

The Screwdriver You Don’t Need, But Probably Want

September 4, 2020 by Danie Conradie 50 Comments

Screwdrivers are simple devices with a simple purpose, and there is generally little fanfare involved with buying yourself a new set. We’ve never seen one marketed as an object of desire, but we have to admit that [Giaco] managed to do precisely that. He created the Kinetic Driver, a ~~fidget spinner~~ precision screwdriver designed to use its rotational momentum to loosen and tighten screws.

The main difference between the Kinetic Driver and other screwdrivers is a big brass mass at the front end for high rotational inertia and a high-quality ceramic bearing at the back end for minimal drag. It uses 4 mm precision bits, so its utility will be limited to small screws, which makes it perfect for working on small electronics.

[Giaco] says the idea came after running a successful Kickstarter campaign for a utility knife, where he found that his favorite screwdriver for the many small screws was one with a fat metal body which allowed it to spin easily. In the video after the break, he gives an excellent insight into the development process. He started by creating a series of 3D printed prototypes to figure out the basic shape, before making the first metal prototype. [Giaco] also shows the importance of figuring out the order of operation for machining, which is often glossed over in other machining videos. Be sure to check out the beautiful launch video at 17:52. Continue reading “The Screwdriver You Don’t Need, But Probably Want” →

Vizy The AI Camera Aims To Ease Machine Vision

August 17, 2020 by Donald Papp 17 Comments

Cameras are getting smarter and more capable than ever, able to run embedded machine vision algorithms and pull off tricks far beyond what something like a serial camera and microcontroller board would be capable of, and the upcoming Vizy aims to be even smarter and easier to use yet. Vizy is the work of Charmed Labs, and this isn’t their first foray into accessible machine vision. Charmed Labs are the same folks behind the Pixy and Pixy 2 cameras. Vizy’s main goal is to make object detection and classification easy, with thoughtful hardware features and a browser-based interface.

Vizy can identify common birds with “Birdfeeder”, one of the several built-in applications that uses local processing only.

The usual way to do machine vision is to get a USB camera and run something like OpenCV on a desktop machine to handle the processing. But Vizy leverages a Raspberry Pi 4 to provide a tightly-integrated unit in a small package with a variety of ready-to-run applications. For example, the “Birdfeeder” application comes ready to take snapshots of and identify common species of bird, while also identifying party-crashers like squirrels.

The demonstration video on their page shows off using the built-in high-current I/O header to control a sprinkler, repelling non-bird intruders with a splash of water while uploading pictures and video clips. The hardware design also looks well thought out; not only is there a safe shutdown and low-power mode for the Raspberry Pi-based hardware, but the lens can be swapped and the camera unit itself even contains an electrically-switched IR filter.

Vizy has a Kickstarter campaign planned, but like many others, Charmed Labs is still adjusting to the changes the COVID-19 pandemic has brought. You can sign up to be notified when Vizy launches; we know we’ll be keen for a closer look once it does. Easier machine vision is always a good thing, because it helps free people to focus on clever ideas like machine vision-based tool alignment.

Open-Source 2 GHz Oscilloscope Probe

May 7, 2020 by Ted Yapo 8 Comments

If you do any work with high-speed signals, you quickly realize that probing is an art unto itself. Just having a fast oscilloscope isn’t enough; you’ve got to have probes fast enough to handle the signals you want to see. In this realm, just any old probe won’t do: the input capacitance of the classic RC probe you so often see on low-bandwidth scopes starts to severely load down a circuit well below 1 GHz. That’s why we were really pleased to see [Andrew Zonenberg’s] new open-source design for a 2 GHz resistive probe hit Kickstarter.

The design of this new probe looks deceptively simple. Known as a Z₀-probe, transmission-line probe, or resistive probe, the circuit works as a voltage divider, created from the 50-Ohm input impedance of a high-speed oscilloscope input and an external resistor, to reduce loading on the circuit-under-test. In this case, the input resistance has been chosen to be 500 Ohms, yielding a 10x probe. In theory, building such a probe is as simple as soldering a resistor to the end of a piece of coaxial cable. You can do exactly that, but in practice, optimizing a design is much more complex. As you can see in the schematic, just choosing a resistor of the right value doesn’t cut it at these frequencies. Even the tiny 0402-size resistors have parasitic capacitance and inductance that affect the response, and choosing a combination of parts that add to the correct resistance but reduce the overall capacitive loading makes a huge difference.

Don’t be fooled: the relatively simple schematic belies the complexity of such a design. At these speeds, the PCB layout is just as much of a component as the resistors themselves, and getting the transmission-line and especially the SMA footprint launch correct is no easy task. Using a combination of modeling with the Sonnet EM simulator and empirical testing, [Andrew] has ended up with a design that’s flat (+/- 1 dB) out to 1.98 GHz, with a 10-90% rise time of 161 ps. That’s a fast probe.

The probe comes in a few options, from fully assembled with traceable specs to a DIY solder-it-yourself version. You probably know which of these options you need.

We really like to see this kind of knowledge and thoroughness go into a project, and we’d love to see the Kickstarter project reach its goals, but perhaps the best part is that the design is permissively open-source licensed. This is a case where having the board layout open-sourced is key; the schematic tells you maybe half of what’s really going on in the circuit, and getting the PCB right yourself can be a long and frustrating exercise. So, have a look at the project, and if you haven’t got probes suitable for your fastest scopes, build one, or better yet, support the development of this exciting design.

We’ve seen [Andrew’s] oscilloscope work before, like glscopeclient, his remote oscilloscope utility program.

Failed: Air Umbrella

January 25, 2020 by Al Williams 43 Comments

About five years ago, a Kickstarter popped up for the air umbrella. It wasn’t long before the project fell apart and the company made at least some refunds. Old news, we know. But [The Action Lab] recently explored the physics behind the air umbrella and why it wouldn’t be very practical. (Video, embedded below.)

Notice we said not very practical, not unworkable. It is possible to shoot rain away from you by using pressurized air. The problem is you need a lot of air pressure. That means you also need a lot of battery. In particular, [The Action Lab] used a leaf blower and even with that velocity, there was only minimal water deflection. In other words, you are still going to get wet.

Continue reading “Failed: Air Umbrella” →