Obsolete E-Reader Gets New Life

November 13, 2023 by Bryan Cockfield 6 Comments

For those who read often, e-readers are a great niche device that can help prevent eye fatigue with their e-ink displays especially when compared to a backlit display like a tablet or smartphone, all while taking up minimal space unlike a stack of real books. But for all their perks, there are still plenty of reasons to maintain a library of bound paper volumes. For those who have turned back to books or whose e-readers aren’t getting the attention they once did, there are plenty of things to do with them like this e-book picture frame.

The device started life as a PocketBook Basic Touch, or PocketBook 624, a fairly basic e-reader from 2014, but at its core is a decent ARM chip that can do many more things than display text. It also shipped running a version of Linux, which made it fairly easy to get a shell and start probing around. Unlike modern smart phones this e-reader seems to be fairly open and able to run some custom software, and as a result there are already some C++ programs available for these devices. Armed with some example programs, [Peter] was able to write a piece of custom software that displays images from an on-board directory and mounted the new picture display using an old book.

There were a number of options for this specific device that [Peter] explored that didn’t pan out well, like downloading images from the internet to display instead of images on the device, but in the end he went with a simpler setup to avoid feature creep and get his project up and running for “#inktober”, a fediverse-oriented drawing challenge that happened last month. While not strictly in line with a daily piece of hand-drawn artwork, the project still follows the spirit of the event. And, for those with more locked-down e-readers there’s some hope of unlocking the full functionality of older models with this FOSS operating system.

STM32 Offers Performance Gains For DIY Oscilloscope

October 18, 2023 by Bryan Cockfield 23 Comments

There’s no shortage of cheap digital oscilloscopes available today from the usual online retailers, but that doesn’t mean the appeal of building your own has gone away — especially when we have access to powerful microcontrollers that make it easier than ever to spin up custom gear. [mircemk] is using one of those microcontrollers to build an improved, pocket-sized oscilloscope.

The microcontroller he’s chosen is the STM32F103C8T6, part of the 32-bit STM family which has tremendous performance compared to common 8-bit microcontrollers for only a marginally increased cost. Paired with a small 3-inch TFT color display, it has enough functions to cover plenty of use cases, capable of measuring both AC and DC signals, freezing a signal for analysis, and operating at an impressive 500 kHz at a cost of only around $15. The display also outputs a fairly comprehensive analysis of the incoming signal as well, with the small scope capable of measuring up to 6.6 V on its input.

This isn’t [mircemk]’s first oscilloscope, either. His previous versions have used Arduinos, generally only running around 50 kHz. With the STM32 microcontroller the sampling frequency is an order of magnitude higher at 500 kHz. While that’s not going to beat the latest four-channel scope from Tektronix or Rigol, it’s not bad for the form factor and cost and would be an effective scope in plenty of applications. If all you have on hand is an 8-bit microcontroller, though, we have seen some interesting scopes built with them in the past.

Removing The Air Gap From An IPad Display

October 12, 2023 by Lewin Day 31 Comments

Some recent models of the Apple iPad have a rather annoying air gap in between the display and the outer touch surface. This can be particularly frustrating for users that press hard or use the Apple Pencil regularly. It is possible to eliminate this gap in the iPad 9, at least, as demonstrated by [serg1us_eng]. (Warning: TikTok)

Doing the job well takes some finesse, however, and plenty of fancy equipment. The iPad’s front touch glass was first covered to avoid scratches during the work, and then heated to 60 C to remove it. The display was also removed, with several glued-down ribbon cables having to be carefully pried off to avoid damage. A layer of transparent material was then cut to size to fit in the gap between the display and the front glass, with the stack laminated together. Getting this result without air bubbles or dust particles spoiling the result involved the use of a heated press and a clean room, which are now widely used in phone repair shops around the world.

For the average user, it might not be a big deal. For power users and touch-and-feel fanatics, though, there’s great appeal in an iPad without this annoying flaw. Video after the break.

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Hackaday Prize 2023: AC Measurements Made Easy

October 12, 2023 by Bryan Cockfield 17 Comments

When working on simple DC systems, a small low-cost multimeter from the hardware store will get the job done well enough. Often they have the capability for measuring AC, but this is where cheap meters can get tripped up. Unless the waveform is a perfect sinusoid at a specific frequency, their simple algorithms won’t be able to give accurate readings like a high-quality meter will. [hesam.moshiri] took this as a design challenge, though, and built an AC multimeter to take into account some of the edge cases that come up when working with AC circuits, especially when dealing with inductive loads.

The small meter, an upgrade from a previous Arduino version that is now based on the ESP32, is capable of assessing root mean square (RMS) voltage, RMS current, active power, power factor, and energy consumption after first being calibrated using the included push buttons. Readings are given via a small OLED screen and have an accuracy rate of 0.5% or better. The board also includes modern design considerations such as galvanic isolation between the measurement side of the meter and the user interface side, each with its own isolated power supply. The schematics and bill-of-materials are also available for anyone looking to recreate or build on this design.

With the project built on an easily-accessible platform like the ESP32, it would be possible to use this as a base to measure other types of signals as well. Square and triangle waves, as well as signals with a large amount of harmonics or with varying frequencies, all need different measurement techniques in order to get accurate readings. Take a look at this classic multimeter to see what that entails.

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ESP32 Drives Tiny FM Radio

September 14, 2023 by Bryan Cockfield 21 Comments

Even as music streaming services and podcast apps dominate most of our listening time, it’s still a great idea to keep a radio on hand, if for nothing else than in emergency situations. After all, blizzards, hurricanes, and other natural disasters can quickly take out both home and mobile Internet access. If you’d like to have an FM radio with the absolute smallest footprint, take a look at this one built around an ESP32.

While the radio uses the ESP32 as the main control board hosted by a TTGO T-Display board which adds a 1.14 inch ST7789V IPS panel, it also makes use of the TEA5767 chip for handling the FM radio signals. As [Volos Projects] has it programmed, the ESP32 stores five preset channels which can be toggled using two buttons at the bottom of the device. There’s also some circuitry to handle output to headphones or a stereo.

For making the radio even smaller, some of the audio processing could be done on the ESP32 instead, although its much simpler to take a slightly larger footprint and offload this to an audio processing chip. Since the source code for this project is open, modifications could be done including adding seek/tune functionality instead of relying only on presets. If you’re not building this for emergencies, though, and your entire area is dominated by cookie cutter corporate-owned radio stations, an ESP32 with an internet connection is great for accessing better radio stations around the world.

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A Usable Arduino Debugging Tool

July 31, 2023 by Bryan Cockfield 16 Comments

For as popular as the Arduino platform is, it’s not without its problems. Among those is the fact that most practical debugging is often done by placing various print statements throughout the code and watching for them in the serial monitor. There’s not really a great way of placing breakpoints or stepping through code, either. But this project, known as eye2see, hopes to change that by using the i2c bus found in most Arduinos to provide a more robust set of debugging tools.

The eye2see software is set up to run on an Arduino or other compatible microcontroller, called the “probe”, which is connected to the i2c bus on another Arduino whose code needs to be debugged. Code running on this Arduino, which is part of the eye2see library, allows it to send debugging information to the eye2see probe. With a screen, the probe can act as a much more powerful debugger than would otherwise typically be available, being able to keep track of variables in the main program, setting up breakpoints, and outputting various messages on its screen.

The tool is not without its downsides, though. The library that needs to run on the host Arduino slows down the original program significantly. But for more complex programs, the tradeoff with powerful debugging tools may be worth it until these pieces of code can be removed and the program allowed to run unencumbered. If you’d like to skip needing to use a second Arduino, we’ve seen some other tools available for debugging Arduino code that can run straight from a connected PC instead.

Hackaday Prize 2023: Tilting Mechanical Panels Make A Beautiful Display

July 17, 2023 by Donald Papp 13 Comments

Mechanical displays use a variety of different methods to represent data with physical objects, and [AIRPOCKET]’s Mechanical Display aims to be a platform anyone can use. Each “pixel” in this display is a panel of some kind, and different effects can be had by moving individual panels to different angles. Not only can images be represented, but the patterns of the movements themselves can be beautiful as well.

The panels are an important part of how the display presents, so the design makes them easy to change out.

These sorts of displays are fertile ground for artistic expression (one memorable implementation of this basic idea was the wooden mirror, which used varnished tiles of wood) but anyone looking to use the concept has usually been on their own when it comes to implementation.

The idea [AIRPOCKET] has is to make this kind of installation easier to implement. This method uses economical mini RC servos and 3D-printed pieces to create modular segments that can be assembled into whatever configuration one may need.

The material of the panels matters, too. Just below the page break, you can see a large unit with each “pixel” consisting of a mirrored square that reflects daylight. There’s also a video of an earlier prototype that uses some ridged two-color pieces to create a simple 4×4 three-level greyscale display.

There are a lot of possibilities if [AIRPOCKET] can make this sort of display more easily accessible, and that makes it a contender in the 2023 Hackaday Prize.

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