Cutting A Wearable Display In Half Is Harder And Simpler Than It Seems

In the world of hardware hacking, you sometimes spend a ridiculous amount of time debugging a problem, only to find a simple solution that was right in front of you the whole time. [Zack Freedman] got a good dose of this while building the Optigon V2, a modified Epson Moverio wearable display he uses as a teleprompter in all his videos. He prefers having the teleprompter over his left eye only, but the newer version of the Moverio would shut off both sides if one is disconnected, so [Zack] needed a workaround.

Looking for some help from above, [Zack] requested developer documentation for the display module from Epson, but got declined because he wasn’t a manufacturer or product developer. Luckily, a spec sheet available for downloaded from the Epson website did contain a lot of the information he needed. An STM32 monitored the temperature of each display module over a pair of independent I2C interfaces, and would shut down everything if it couldn’t connect to either. This led [Zack] to attempt to spoof the I2C signals with an ATmega328, but it couldn’t keep up with the 400 kHz I2C bus.

However, looking at the logs from his logic analyzer, [Zack] found that the STM32 never talked to both display modules simultaneously, even though it is capable of doing so. Both displays use the same I2C address, so [Zack] could simply connect the two I2C buses to each other with a simple interface board, effectively making the left display “spoof” the signals from the right display.

Wearable displays need some fancy optics to be practical, you can’t just stick an OLED to your face. Two other interesting projects from [Zack] are his modular mechanical keyboard and the Gridfinity 3D printed storage system.

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The Rollercoaster Of Developing The Ultimate Hackable Keyboard

When designing anything with “hackable” in the punchline, scope creep is an integral part of the process. You end up trying to create something to potentially be an infinite number of things for an infinite number of users. [Zack Freedman] is going really deep down the rabbit hole with his MiRage keyboard and has been documenting the progress in his usual entertaining style, with some cautionary notes included.

The most fascinating tale from this come about as a result of adding RGB LEDs beneath the keys, while still allowing everything to function when the keyboard is split in two. Thanks to an IO expander chip in one side of the board, a standard TRRS audio cable is enough to link both sides together. But the addition of addressable LEDs meant more lines were required.

[Zack] thought he had found a solution in the form of SATA cables, but it turns out all SATA cables internally connect pins 1,3, and 7, making them useless for this application. He realized he had no choice but to add a second microcontroller to the “dumb” side of the keyboard and return to I2C over a TRRS cable. However, the RP2040-based Seeed XIAO’s I2C absolutely refused to play along. After a fortnight of frustrating debugging, it turns out there was a bug in the pin definitions. Fortunately, this also revealed that the XIAO had an undocumented secondary I2C interface, which he plans to configure as a peripheral to make the keyboard almost infinitely expandable with additional keys.

An earlier version of the MiRage featured tactile OLED displays, but it turns out the thin panes of glass don’t handle repeated flexing well, so they had to be scrapped. In their place came a touchscreen E-paper display, but now this seems to be evolving into a pluggable module for any input device that your heart desires, including possibly a haptic SmartKnob. Another major update are PCB footprints that support both CHOC and MX switches.

It all started with the MiRage V1 keyboard intended to for use in an updated version of [Zack]’s cyberdeck. After realizing how many people were interested in the keyboard but not the cyberdeck, he shifted focus to refining the MiRage.

This project still has some way to go, so we’ll certainly be keeping our eye on it. In the meantime, we’ve recently covered another exceptionally customizable keyboard that might catch your fancy.

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A Massive Modular Smartwatch To Match Your Sci-Fi Fantasies

Modern smart watches have some incredible features, but they still don’t stack up to what science fiction promised us, both in size and capabilities. Fortunately, [Zack Freedman] has set out to change that with the Singularitron, a modular wearable computer that is less Apple Watch and more Pip-Boy.

The most striking features of this monstrosity is its size and the out-of-production four-line VFD display. The inputs consist of a row of large RGB-illuminated buttons and a rotary encoder mounted at an angle to curve around the wearers arm. On the inside are a pair of PCBs with an integrated Teensy 3.2, BLE module, motion processing module, haptic driver and power circuitry drawing from a removable 18650 battery. The armband is from a commercial wrist mounted barcode scanner which attaches to the Singularitron with a quick-detach mount.

A major feature of the Singularitron is its modularity. Arrayed around its edges are four slots with spring-loaded contacts for add-on modules. Modules have access to the SPI and I2C busses, two GPIO pins, 3.3 V and 5 V lines. Each module also contains an EEPROM chip to store the module’s ID and any configured settings, allowing modules to be hot swapped and automatically recognised. [Zack] has created a number of modules, like a laser pointer, environmental sensor, OLED display and a Teensy 4.0 to blink an LED. When a module is plugged or inserted, a series of randomly generated status messages flash across the display, thanks to an awesome little library which we are absolutely copying for our own projects. Ironically, keeping the time is one of the Singularitron weak points, since [Zack] wasn’t able to fit a backup battery inside, so the time needs to be reset when the battery dies. Maybe a module with an RTC and backup battery is the perfect solution. Continue reading “A Massive Modular Smartwatch To Match Your Sci-Fi Fantasies”