A digital caliper connected to a tablet computer

Custom Interface Adds USB And Wi-Fi To Digital Calipers

October 17, 2022 by Robin Kearey 26 Comments

Although old-school machinists typically prefer the mechanical vernier scale on their trusty calipers, many users nowadays buy calipers with a digital readout. These models often come with additional features like differential measurements, or a “hold” function for those situations where you have to maneuver the instrument somewhere deep inside a machine. Another useful feature is a data link that lets you log your measurements on a computer directly instead of manually entering all the values.

The VINCA-branded caliper that [Liba2k] bought has such a data link feature, which requires a USB adapter that’s sold separately. There is a micro-USB connector on the tool itself, but instead of implementing a USB interface, this is used to carry a proprietary serial protocol — a design decision that ought to be classified as a felony if you ask us. Rather than buying the official USB adapter, [Liba2k] decoded the protocol and built his own interface called VINCA Reader that can connect through either USB or Wi-Fi.

The serial format turned out to be a simple serial bus that clocks out 24 bits at a time. In order to adapt its 1.2 V signal level to the 3.3 V used by an ESP32, [Liba2k] designed a simple level shifter circuit using a handful of discrete components. The ESP can communicate with the computer through its Wi-Fi interface, for which [Liba2k] wrote a spreadsheet-like application; alternatively, an ordinary USB cable can be connected to emulate a keyboard for use with any other software.

With its added Wi-Fi feature, the VINCA Reader is actually more complete than the official USB adapter, and will probably be cheaper as well. The serial interface appears to be common to all caliper manufacturers, although many went for a more sensible connector than micro-USB. An automated readout system is particularly handy if you have to make thousands of similar measurements.

A cyclotron clock display, mounted on a wooden base. There are two stepper motors exposed on either side. There is a panel installed in the wooden base with a red button on the left, two knobs and four smaller buttons in a two by two grid on the right.

A Flipping, Perpetually-Rotating Clock

October 13, 2022 by Abe Connelly 6 Comments

Clocks are a mainstay of hackers and makers, as they provide a way to explore creative designs while still maintaining a functional aspect to the project. [Brett Oliver] follows this tradition in making a cyclotron clock that uses a perpetual rotating digit concept from a 1900s desk flip calendar.

Each digit of the clock has a rotating chamber that’s big enough to fit a group of tiles inside that have digits printed on either face. The tiles are sized and stacked in such a way that the rotation of the chamber allows the next tile to slide in front of the old one. Specific digits are revealed by rotating the chamber a number of times.

Each of the four digits positions has a 28BYJ-48 stepper motor to rotate the chamber, with each motor being driven by a ULN2003 driver module. The main microcontroller is a ESP32 WROOM, and an I2C compatible DS3231 real time clock (RTC) module keeps time. All of the motors are driven off of an LM2596 module that provides 7 V, while the ESP32 and RTC are powered from a USB connector.

The different modes and the ability to set time is done through a panel that has various buttons and knobs. The whole clock is mounted on a custom wooden base that has cutouts for the panels and cabling. [Brett Oliver] has done a great job of documentation, going into detail about the mechanics and electronics of the build. Design files, including STLs of the various components, are also available for download. Be sure to check out the video after the break.

We’ve featured a flip calendar with a similar operating principle before which clearly shows the inner workings of the mechanism.

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Tiny Thin Client Is Small But Compatible

October 13, 2022 by Al Williams 10 Comments

We were impressed with [moononournation’s] tiny thin client project. It claims to use an Arduino, but as you might guess it is using the Arduino software along with a network-enabled microcontroller like an ESP32. The impressive part is that it is standards-compliant and implements VNC’s RFB protocol.

The original coding for RFB on Arduino is from [Links2004] and armed with that, the thin client is probably easier to create than you would guess. However, this project wanted to use a larger screen and found that it led to certain problems. In particular, the original code had a 320×240 display. This project was to use an 800×480 display, but with the limits on the ESP32, the frame rate possible would be under 7 frames per second. The answer was to combine a 16-bit parallel interface with better compression back to the VNC server.

The little keyboard is probably not very practical, but it is compact. That would be another easy thing to modify. Currently, the keyboard uses I2C, but it would be straightforward to change things up. This would be a worthy base to build a bigger project on top. A 3D printed enclosure would be nice, too.

We’ve seen a number of projects built around commercial thin clients. Some from defunct businesses are good sources for obscure parts, too.

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This ESP32 CAN!

October 10, 2022 by Jenny List 15 Comments

Since modern cars use the CAN bus for so many of their functions, it’s unsurprising that it’s a frequent object of interest for those in our community. Some people go no further than commercial plug-in analysers, while others build their own CAN devices. This is what [Magnus Thomé] has done, with his RejsaCAN microcontroller board.

It’s a small PCB with an onboard CAN interface from an ESP32-S3 and a car-friendly power supply circuit, and perhaps most importantly, it has an auto-shutdown feature to prevent battery drain. Software-wise it’s a blank piece of paper for the user to roll their own application, but since the ESP32 is supported by the Arduino ecosystem, there are libraries that make talking CAN as easy as it can be.

[Magnus] has a list of potential applications for the board, many of which take advantage of the ESP’s wireless capabilities. So far, [Magnus] has hooked it up to an LCD display, but we can see so many other useful things coming out powered by something like this.

You haven’t tried playing with your car’s CAN bus yet? Maybe you should read this to whet your appetite.

RatPack Is A Wearable Fit For A Rodent

October 5, 2022 by Lewin Day 6 Comments

Rats are often seen as pests and vermin, but they can also do useful jobs for us, like hunting for landmines. To aid in their work, [kjwu] designed the RatPack, a wearable device that lets these valiant rats communicate with their handlers.

The heart of the build is an ESP32-CAM board, which combines the capable wireless-enabled microcontroller with a small lightweight camera. It’s paired with a TinyML machine learning board, and it’s all wrapped up in a 3D printed enclosure that serves as a backpack to fit African Giant Pouched rats.

The RatPack can provide a live video feed. However, its main purpose is to track the rat’s movements through the use of an accelerometer. This data is then fed to the machine learning subsystem, which analyzes it to detect certain gestures the rats have been trained to make. The idea is that when the rat identifies an object of interest, such as a landmine, it will perform a predetermined gesture. The RatPack would then detect this, and transmit a signal to the rat’s handlers. Given a rat’s limbs are all on the bottom of its body, this approach is useful. It’s kind of hard to ask a rat to press a button on its own back, after all.

Finding and carefully disposing of unexploded ordnance is a problem facing many societies around the world. We’re lucky in many cases that the rats are helping out with this difficult and dangerous job.

Rib Cage Lamp Kicks It Up A Notch With Party Mode

October 1, 2022 by Donald Papp 8 Comments

We think [Michelle]’s sound-reactive rib cage lamp turned out great, and the photos and details around how it was made are equally fantastic. The lamp is made of carved and waxed wood, and inside is a bundle of LED lighting capable of a variety of different color palettes and patterns, including the ability to react to sound. Every rib cage should have a party mode, after all.

The LED strip is fashioned into an atom-like structure.

Turns out that designing good rib cage pieces is a bigger challenge than one might think. [Michelle]’s method was to use an anatomical 3D model as reference, tracing each piece so that it could be cut from a flat sheet of wood.

The resulting flat pieces then get assembled into a stack, with each rib pointed downward at a roughly 20 degree angle. This process is a neat hack in itself: instead of drilling holes all at exactly the same angle, [Michelle] simply made the holes twice the diameter of the steel rod they stack on. The result? The pieces angle downward on their own.

The LED lighting is itself a nice piece of work. The basic structure comes from soldered solid-core wire. The RGB LED strip gets wound around that, then reinforced with garden wire. The result is an atomic-looking structure that sits inside the rib cage. An ESP32 development board drives everything with the FastLED library.

Code for everything, including the sound-reactive worky bits, which rely on an INMP441 I²C microphone module is all available on GitHub. And if you want to make your own sound-reactive art, make sure to check out these arms as well.

Want to see the rib cage in action? A short demo video is embedded below that demonstrates the sound reactivity. Equally applicable to either party or relaxation modes, we think.

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Trombone Controls Virtual Trombone

September 27, 2022 by Bryan Cockfield 5 Comments

Guitar Hero was a cultural phenomenon a little over a decade ago, and showed that there was a real fun time to be had playing a virtual instrument on a controller. There are several other similar games available now for different instruments, including one called Trombone Champ that [Hung Truong] is a fan of which replaces the traditional guitar with a trombone. The sliding action of a trombone is significantly different than the frets of a guitar, making it a unique challenge in a video game. But an extra challenge is building a controller for the game that works by playing a real trombone.

Unlike a guitar which can easily map finger positions to buttons, mapping a more analog instrument like a trombone with its continuous slide to a digital space is a little harder. The approach here was to use an ESP32 and program it to send mouse inputs to a computer. First, an air pressure sensor was added to the bell of the trombone, so that when air is passing through it a mouse click is registered, which tells the computer that a note is currently being played. Second, a mouse position is generated by the position of the slide by using a time-of-flight sensor, also mounted to the bell. The ESP32 sends these mouse signals to the computer which are then used as inputs for the game.

While [Hung Truong] found that his sensors were not of the highest quality, he did find the latency of the control interface, and the control interface itself, to be relatively successful. With some tuning of the sensors he figures that this could be a much more effective device than the current prototype. If you’re wondering if the guitar hero equivalent exists or not, take a look at this classic hack from ’09.

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