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We’ve covered PJRC forum member CryHam’s Teensy 3.2-powered KC Keyboard Controller before, but now it’s back with a significant upgrade, in the form of the Teensy 4.0-based K.C.4 controller for matrix keyboards.

If you have an inexpensive dome-switch keyboard that lacks the features of higher-end mechanical keebs, like key mapping, layers, macros, and a screen that can run demos, games, and an RTC-backed clock…although…wait — we’re not sure we’ve seen that on any keyboard, come to think of it?! — so maybe give K.C.4 a look regardless!

Configuration starts as simply as a Teensy 4.0 and ILI9341 TFT LCD display. Adding serial EEPROM such as a 25LC256, a DS18B20 1-wire temperature sensor and 4.7k resistor, and LED/photoresistor will get you all of the bells and whistles, such as temperature graphs, and an external 5V power supply will even let you display and retain data without PC power.

A wealth of information can be found on the project page, with source and schematic available on GitHub, and various demos available on YouTube, as well as the one below.

What do you get when you cross a Teensy 3.6 with a Raspberry Pi 3B, 2448 RGB LEDs, a thousand pieces of origami, and a papier-mâché sculpture?

If you’re PJRC forum member beil, the answer is Wefted Waveforms, an “interdisciplinary light sculpture” completed as part of their Visual Arts degree at Queensland University of Technology in Brisbane, Australia.

The project uses gLEDiator to animate the LEDs, along with our OctoWS2811 Adaptor to wire them up. A detailed write-up can be found on the Core Electronics project site, and a rather hypnotic video of the Wefted Waveforms in action can be seen in the video below.

Mike Mayfield’s 1971 Star Trek was a strategy game designed for computers with no graphical display.

While Teensy boards are more than capable of driving advanced graphical displays, PJRC forum member jim lee ported the BASIC source to Arduino with the help of Arduino forum member WildBill, and then added a GUI to provide keyboard input, and … an entire Teensy 3.2-based handheld unit for on-the-go play. The source, available on GitHub, also provides a version that runs on the Arduino IDE’s serial monitor, so that you can try it without any extra hardware.

A popular meme pokes fun at the DIY mechanical keyboard community by suggesting that enthusiasts must surely realize significant savings by building their own keyboards rather than purchasing a commodity preassembled unit,

whereas anyone who has ever even dipped their toe into that rabbit hole knows that this is typically far from the case. Rather than toss some keycaps, switches, a board and a case into a shopping cart and whacking them all together, however, PJRC forum user stefan.jakobsson took things to the next level with a scratch-built, Teensy LC-based 60% keeb.

We’re not sure what switches or caps are in use here, but the plate is 3d-printed, and the matrix is hand-soldered, dead bug-style, rather than using a PCB. A bespoke 1.5 steel plate forms the bottom case. Custom firmware, written using the Keyboard class, supports a standard layer plus second Fn layer, and has a simple built in debouncing handler. Source code is available in the thread, although Stefan is still working through some issues with sleep mode.

‘Twas the night before Christmas, when all through the house, not a creature was stirring, not even a mouse – which was frustrating,

because the Mr. Christmas “The Night Before Christmas House” was supposed to be playing audio and flashing light bulbs that correspond to the story, but a previous failed repair attempt had rendered it inoperable. That is, until PJRC forum member edseitz replaced the cassette player and associated electronics with a Teensy 3.6 and Prop Shield!

The seventeen light bulbs were replaced with LEDs, and a custom class was added to simulate the warming and dimming of traditional bulbs. The Teensy’s microSD storage was ideal for .WAV files of the original cassette audio, with their playback facilitated by the Prop Sheild’s integrated 2-watt audio amp. And we heard edseitz exclaim, as he hid the wiring out of sight – “Happy Christmas to all, and to all a good night!”

We’ve covered plenty of Teensy-powered grooveboxes on the blog here before, but this Reddit post unveiling the Audio Enjoyer XR-1 really caught our eye. If you’re looking to go DAWless, this Teensy 4.1-powered drum machine, sampler, and synthesizer looks like a great all-in-one machine.

Modeled after Roland TR-909 sequencing conventions, it has 16 banks of 16 patterns of 16 tracks, with up to 64 steps per track.

Around back are standard stereo in/out and 5-pin DIN MIDI jacks, and eight 0-10V CV/gate outputs. Mono RAW or stereo WAV samples are stored on microSD, along with project data. The unit also features a capacitive touch keyboard and hard buttons arranged in an MPC-style 4×4 grid, plus an OLED display for presenting the UI. A demonstration of the XR-1 can be seen below, and Audio Enjoyer have a signup form on their website for more info.

When injket printers became commercially available to the home consumer in the 90s, they seemed like a tiny revolution; gone was the dominance of the drab black and white laser, with cheap devices providing full color at a fraction of the cost.

Exploitative refill prices, evil DRM, and a transition away from paper to digital has somewhat stymied the inkjet market of late, but Dutch maker Yvo de Haas is bringing inkjets back with his Teensy 3.5-based controller for the HP-45 inkjet printhead. One application of this controller that caught our eye is an SMD tape printer that lets you mark your parts just like the big vendors.

Using custom software, the controller can manipulate each nozzle on the cartridge in order to output bitmaps. The software and firmware are available on GitHub, and the below video provides a brief glimpse of the controller in action.

Teensy forum member and M.CU.M.E retrocomputing emulator innovator Jean-Marc is back with yet another emulation project, this time in the form of a MAME (Multiple Arcade Machine Emulator) port and accompanying handheld hardware.

Memory limitations mean that games are spread across several projects, but several hundred are supported overall.

Hardware consists of a Teensy 4.0 and ILI9341 or ST7789 SPI display plus an analog thumb joystick and three buttons. While pictures show a perfboard assembly, there is a KiCad PCB file in the repo, which should facilitate reproduction of the optional I2C keyboard, itself powered by a dedicated ATmega328P.

While sound is not yet supported, and emulation is limited to fairly old hardware, it’s still pretty cool to see Konami’s 1981 hit Scramble running on a DIY handheld. Watch more classics demoed in the videos below, and grab the source and pinout/PCB on GitHub.

ROM emulators have become extremely common for classic consoles like the NES and Game Boy, but what about earlier computers that also used edge-connector-style expansions?

 

HP Series 80 group member Tim Nye developed a Teensy 3.6-based ROM-emulating plug-in module that allows users of the early 1980s pre-PC HP 83/85 and 86/87 to select any of the systems’ available ROMs to be loaded from flash memory.

The board includes some unique features, such as a 6V level shifter to bridge the HP’s bus with the Teensy’s 3.3V logic, and a diode to prevent the HP’s 5V power from flowing via USB to a connected computer during programming. One interesting challenge was that the Teensy needs to boot before the HP, but the /HALT line on the HP’s bus can be driven by the Teensy to only permit the CPU to start once it’s ready.

The board appears to be a one-off with no information on purchasing or creating one’s own, but the HP Series 80 group is an active community, so drop them a note if you have a Series 80 with an empty expansion slot!

With over ten thousand Eurorack modules already available in the world, you’d want to be MAD to create a whole new suite of them.

But Michele Perla is just our type of bonkers, and has created a set of Modular Audio Devices that work together as a bridge between analog synths, MIDI keyboards, PCs, and audio interfaces.

The Teensy 3.6-powered CORE module features USB communication with a host PC, 5-pin DIN MIDI in and out jacks, eight CV outs, 8 gate outs, one clock in and one clock out, and a TFT display with four potentiometers for configuration. The “lite” version features a Teensy 3.2.

The CTRL module connects to the CORE via I2C, and adds up to 24 analog sensors, buttons and LEDs, with three address bit jumpers allowing up to eight CTRL modules to be used together. The intuitively-named CODEC module adds an AK4558 CODEC featuring stereo inputs and outputs, as well as a headphone jack, and aux in/out connectors. VCO, VCF, and VCA modules flesh out the line completely.

A demonstration of the CORE prototype can be found in the video below, with more information available on Hackaday, Facebook, and Instagram.