Blog Posts

Mechanical engineer and YouTuber Clay Builds has is restoring a late-90s robot using a Teensy 4.0 and ESP32.

The Nomadic Technologies N150 was purchased at auction in a non-functional state. Clay is attempting to “rebrain” it with modern microcontrollers in order to use the original ultrasonic rangefinders and bump sensors in conjunction with modern SLAM (simultaneous localization and mapping) algorithms.

Teensy is used to read the ultrasonic array, limit switches and motor encoders, with the latter used for navigation via dead reckoning. It is also used for the motor drivers, which provide locomotion. Source code for the current iteration can be found on GitHub, and a detailed video can be found below.

charje has created the Power User Keyboard, a unique custom keyboard with a non-conventional bottom row of keys. The result of the extensive documentation of the project is effectively a general-purpose guide for the creation of Teensy-based custom keyboards.

With full detail of parts, cost, and tools to create the layout, case, and firmware (automatically generated by QMK), charje’s project write-up provides a complete end-to-end roadmap. We’d love to see a 7-row ThinkPad-style keyboard implemented along similar lines! Check out the project’s sourcehut page for more details.

Brett has put together a ten-minute video guide to using USB MIDI with Teensy. The succinct presentation shows how to interface a classic 5-pin MIDI DIN connector to a modern Digital Audio Workstation (DAW) — in this case, Cakewalk — using Teensy’s USB MIDI capabilities.

Brett details the code for both sending and receiving MIDI data, allowing recording of a MIDI device to a DAW, and playback from the DAW to the device. Brett points out that such an interface could just be purchased “for a tenner,” but what would be the fun in that? Moreover, this basic project can serve as the foundation of all kinds of MIDI tools and contraptions. Complete instructions, as well as code, can be found in the video below.

Jean-Marc, is it it once again, this time with the tiny, Teensy 4.1-based, T-COMPUTER.

Jean-Marc is the creator of the Atari ST Emulator and MAME Arcade Machine Emulator. His latest project, The T-COMPUTER is a full-featured handheld computing platform, with 42 keys (including D-pad and buttons for gaming) and a built-in 320×240 TFT display. While its small size makes it ideal for on-the-go use, VGA and 16-bit stereo DAC outputs, as well as USB host input for keyboard/mouse/etc., as and a DB9 Atari-style joystick input, make for a great desktop experience as well. As always with Jean-Marc’s projects, the schematic, source, BOM, assembly instructions, and more can be found on GitHub. A detailed demo of the computer’s capabilities can be enjoyed below.

Andrei Holingher has built a Nixie tube spectrum analyzer with an S/PDIF input. Inspired by Will Yager’s Rust-based Nixie Tube Audio Meter, the project ports that functionality to Arduino-compatible code, incorporating necessary hardware changes along the way.

Four SAMD21-based QT Py clones drive four tubes each, while a VN7140 Power Management IC distributes power. LM1117 voltage regulators power the 5V and 3V3 microcontrollers, with NCH8200HVs boosting power to the Nixies. The digital optical audio signal is processed by the Teensy Audio Library, then band-filtered into bins, represented by the tubes, with a potentiometer on each for further calibration. Schematics, BOM, firmware, and more can be found on GitHub, and a mesmerizing demonstration can be seen below.

YouTuber James Bruton has created a “screw bike” in the vein of screw-drive tanks, with the additional feat of making it self-balancing. Building upon an earlier front-omni-wheeled bicycle, the latest model can move in any direction, thanks to its four mecanum wheels.

In addition to its steel frame and 3d-printed wheels, the bike features Teensy 4.1 boards to control its ODrive motors via CAN bus. BNO08x IMUs work with the Teensy to help keep things upright. The whole crazy thing can be seen in action below, with source code and CAD files available on GitHub.

Andy Belov has created a general-purpose programmable musical instrument.

With 18 touch sensors, a touchscreen, MIDI, and Bluetooth, it is intended as a blank canvas (or control surface!) on which to create new musical experiences.

Based around a Teensy 3.6 and Audio Adaptor Board, the device adds two custom PCBs and a fun enclosure to create a music-making device around the size of a handheld game console.

It can currently simulate a saxophone, flute, drums, trumpet, or steel drums. Source code can be found on GitHub, and demonstrations can be seen in the videos below.

Brace yourselves, because Ted is back with — any guesses? Yep, another drop-in emulator, this time for the 16/32-bit Motorola 68000!

Ted Fried aka MicroCore Labs has been featured a fair number of times on the PJRC blog with his Teensy-based drop-in CPU replacements, including the MCL65-Fast Apple II Accelerator, MCLZ8 Zilog Z80 (RIP!) emulator, and MCL64 Commodore 64 Accelerator.

The MCL68+ emulates both the 68k itself, and the local bus interface (at full speed) thanks to Ted’s prior experience and some new tricks. In the case of the Macintosh 512K, the MCL68+ is able to substitute for the original CPU, while bit-banging the bus at the required 7.8MHz. Byte-wide latches based on 74HCT574 flip-flops are used to power the address and data busses due to the sheer amount of I/O required to emulate the m68k. As always, source code can be found on GitHub, and you can see it in action below.

We’re big fans of Emmanuel Presselin’s original Teensy 3.2-based MiniTouch low-cost synth for children’s music workshops, so we were keen to find out more details when he mentioned a new Teensy 4.0-based MiniTouch 2nd Edition!

The MiniTouch 2.0 features a larger 18-note capacitive touch keyboard, two oscillators (up from one), 8-voice polyphony (from 4), FM and AM “ring” modulation, a noise generator with ladder filter, high- and bandpass filters in addition to the existing low-pass, per-voice filters (with note tracking) vs. a single global filter, and delay and reverb effects. A MIDI interface, EEPROM-backed presets, USB MIDI host, and a new PAM8406 class-D amplifier and larger speaker all bring quality-of-live improvements, while still remaining accessible for workshop participants with around a $35 BOM cost. See it in action below!

ThirdEarthDesign has shared their first project, a sim rig button box.

Based on the Teensy 4.1, it uses a custom joystick interface via USB HID to extend the functionality of an already-impressive rig.

The “box” features 13 momentary buttons, three toggle switches, two eight-way rotary switches (effectively 16 more inputs), X and Y axis inputs via two further rotary encoders, and Z axis via analog Hall effect sensor.

WS2812 RGB LEDs provide backlighting, and two PWM fans simulate the feeling of wind! A 3d-printed enclosure, Cricut-created labels, and a custom PCB round out the professional-looking package. More information and pics on the PJRC forums.