Blog Posts

PJRC forum member lokki, who you may recall from their unique MIDI Bass Guitar project, is back with another fun musical creation, this time in the form of an infrared foot controller.

Based on the Teensy 4.0, this project uses USB Host to transmit the X-Y position of an object (such as a foot) inside the frame to a connected computer; sort of like a giant Kaoss Pad for your toes! In addition to the IR frame, WS2812 LEDs along the edges help indicate the detected coordinates, and four big buttons allow the user to switch between modes.

More information and source code can be found on the PJRC forums, and a demonstration can be seen in the video below.

PJRC forum member Nick Culbertson, who you may recall from the (“world’s smallest?”) Mini MIDI Controller project, is back with more Teensy-based synth goodness, this time in the much larger, cigar-box-sixed Teensy Arcade Synth.

Built around the Teensy 4.0 and Audio Adaptor Board, the project incorporates a rotary encoder and LCD display for selecting parameters, and the eponymous eight 30mm arcade buttons to mash out three-layer polyphonic jams. The Teensy Audio Library was used to do all of the heavy DSP lifting, leaving the GUI and parameter implementation as the “hardest” part. Code and wiring details are available on GitHub, and an excellent tutorial and demo can be enjoyed in the video below.

PJRC forum member MarkusGruen has developed RTMC (Real Time Measure and Control), a universal data acquisition, logging and I/O system. The Teensy 4.1-based platform enables data capture from any I2C, SPI, RS-232, or analog sensor.

Data can be sampled from eight sensors simultaneously at up to 4.4KHz, then transmitted via USB to a host PC for further analysis. The I/O aspect of the system means that actuators can also be connected to create closed-loop control systems. Raspberry Pi Pico-based node units connect to the Teensy-powered hub via standard Ethernet cable. More information about the project, as well as Gerbers, BOMs, schematics and firmware source can be found on GitHub.

PJRC forum member DrM is back with another CCD (charge-coupled device) project, this time a controller for the Hamamatsu S11639-01 linear CCD sensor, with the aim of making high-end scientific instruments more affordable and accessible.

A GitHub repo provides KiCad files and firmware for the sensor/controller set. Some optional register-level enhancements take advantage of the Teensy 4.0’s i.MX RT1060 to provide improved interrupt latency and more efficient SPI transfers from the board’s 16-bit ADC. The included firmware presents a command-line interface over serial for easy interaction and operation. A Python utility and class library facilitate integration into other systems.

YouTuber Stuff Made Here has shared the latest evolution of his intelligent basketball hoops, this time in the form of the ball-seeking hoop.

Powered by a Teensy 3.6, this robotic backboard moves through three-dimensional space to ensure every shot ends with a satisfying swish.

A specially modified basketball’s position is tracked via eight OptiTrack motion-tracking cameras, with the resulting data used to calculate its trajectory in real time.

Six large motors and a pulley system allow the hoop to position itself anywhere in the room, ensuring a perfect shot every time.

See it in action and learn more about how it was made in the video below.

After more than a year of development, sucofunk has released the Beatmaker’s Sketchbook, a Teensy 4.1-based sampler and sequencer. Designed as an open-source alternative to OP-1s and MPCs, it follows a “Sample, Sketch, Arrange, Play” workflow to help take your ideas from simple noodling to live performances.

In addition to the Teensy 4.1, the Beatmaker’s Sketchbook features a 24-key (two octave) keyboard, 12 functional keys, four endless rotary encoders, a 10mm fader, 2″ LCD display, and 32 LEDs. A built-in microphone and 3.5mm line-in facilitate sampling, while line out, MIDI in/out, and headphone output help connect to all of your other gear.

The project’s firmware and hardware can both be found on GitHub, and you can see it in action in the video below.

Andrew J. Harvie and John C. de Mello have created OLIA, an open-source digital lock-in amplifier. Digital lock-in is a method for isolating weak signals to facilitate measurement amongst background noise, which is processed away via digital signal processing (DSP).

The Open Lock-In Amplifier (OLIA) is a Teensy 4.0-based system that can outperform far more expensive commercial devices for around $35. OLIA offers dual-phase lock-in detection at multiple harmonic frequencies up to 50KHz, adjustable levels of input gain, and a comprehensive API for remote control. An optional breakout board allows optical detection down to 40 pW. Complete details about the project, as well as firmware, schematics, and BOM can be found in the original research paper.

Gero Takke has created the Ottopot, a MIDI controller with “nothing but 8 dials.” But what dials they are! 14-bit MIDI CCs (changes) with a 1:1 mapping to physical movement provides an experience more akin to analog pots, but with continuous rotation.

Gero’s controller exceeds the typical resolution of MIDI control messages by sending two 7-bit messages to indicate a “course” and “fine” value, allowing 16384 values, instead of the typical 128. Mainstream DAWs like Ableton, Logic, and Bitwig support 14-bit CCs, although most hardware does not. Gero also recommends re-greasing the pots as part of the assembly process, for an even better experience. And optional LED rings make it even fancier!

Extensive detail, including detailed instructions, BOM, and everything else you need, can be found on Gero’s blog. A great demo can be found in the video below!

The technology we experience as children can have a lasting impression. An algorithm that Mate Steinforth saw at a relative’s house had such an impression that three decades later it drove the creation of a Teensy-based realization in LED form.

Using the SmartLED Shield for Teensy 4 and a 64×64 LED matrix panel, Mate recreated the mesmerizing graphics from the childhood recollection, and shared the source on GitHub.

This algorithm fascinated me as a kid when I saw it at my cousins‘s place. 30ish years later running on LED via @PaulStoffregen Teensy pic.twitter.com/B1r7VTwdCn

— matesteinforth.tez (@MateSteinforth) December 28, 2021

Back in 2017, Paul designed a board for the Cirrus Logic CS42448 chip, which provides gobs of high-quality audio I/O, and shared it on OSH Park. PJRC forum member tubelab.com picked up a few of them, and created a 6-voice polyphonic hybrid digital/analog synth.

The eventual goal is to fit the project inside a guitar, but for now, it uses vacuum tubes for its Moog-style ladder filter, giving it that signature fat Moog sound.

The aim is to achieve six notes of polyphony with three oscillators per note, requiring 18 VCOs. Control is via standard 1V/oct or MIDI. Check out the video below for an overview, and stay abreast of updates via tubelab.com.