grblHAL – CNC Motion Controller

grblHAL is a project started by Norwegian software developer Terje Io to allow the GRBL CNC software to be abstracted from microcontroller-dependent code, facilitating its adaptation to various boards.

PhilB created a breakout board “unkit” (meaning SMT components come pre-soldered so you just have to add through-holes) for the Teensy 4.1, providing 5-axis control for a fraction of the cost of commercial solutions.

The (un)kit is available on Tindie, though Gerbers are also available on GitHub, along with documentation and more. While USB is the default connection, an Ethernet MagJack footprint enables upgrading for more reliable G-Code feeding. The main grblHAL site also contains a great resources page.

JackAL µBITX Add-On Board

We love seeing ham radios built around Teensy, but to paraphrase Xzibit, Jack (W8TEE) and Al (AC8GY) heard you like ham radio kits, so they made the JackAL (get it?) add-on kit for your µBITX transceiver kit, so you can…well we’ll get to what it lets you do…

Rewinding for a moment, the µBITX itself is a HF SSB/CW transceiver kit (that’s High Frequency, Single Side-Band/Continuous Waveform aka Morse code) with digital tuning, a Morse code keyer, and more, designed to be an approachable, understandable radio that you can build yourself. The JackAL add-on board adds a high-resolution 800×480 TFT touch screen, hardware AGC (automatic gain control), and extensive DSP audio functions. A large rotary encoder facilitates fine-tuning, and user presets for most settings are conveniently stored in EEPROM. The kit comes with SMD components pre-populated — just bring your own Teensy 3.6 and Audio Adaptor Board, plus the display of your choice. More information can be found at the µBITX enthusiast site, as well as a dedicated site.

Midbar – DIY Hardware Data Vault

Northstrix (Max) has been working on various iterations of the Midbar DIY Hardware Data Vault, with the latest V3.0 using Teensy 4.1.

These days, everyone uses a password manager (right? if you’re reading this and not using a password manager, remove all of those Post-It notes from around your monitor and go download Bitwarden right now, set it up, and come back when you’re done — we’ll wait!), but Northstrix posits that using a PC-based password manager leaves it vulnerable to malicious processes running on the same machine.

The latest version of Midbar features password, credit card, phone number, and note vaults, plus an encrypted book reader, a data encryptor/decryptor, and data hasher. Teensy’s USB Host functionality enables the connection of a keyboard. Up to 16 logins and 10 credit cards can be stored in EEPROM, with mSD card storage expanding those numbers greatly depending on available storage. 3DES + AES + Blowfish + Serpent Encryption keeps your data safe, and EEPROM is checked for tampering with each unlock. Full instructions to make your own can be found on Instructables, with source code and more project details available on GitHub.

RGB Video Synth

OD_A has created a video synthesizer that uses a Teensy 3.5 to oscillate frequencies into the RGB channels of a VGA signal.

The interface consists of individual sliders for each of the red, green, and blue channels, which are then “mixed” with a video input (in the style of a DJ mixer) to produce glitchy visuals akin to unusually beautiful VHS tracking skew. After some op-amp and other circuitry issues, OD_A was able to figure out a way to abuse the VGA spec to achieve the desired results, thanks to guidance from the PJRC forum community. See the results in the video below, and check out more of OD_A’s projects and hacks at

R/C Transmitter and Receiver

Radio control systems can be expensive and confusing with their various incompatible protocols (FHSS, DSSS, and so on), but Malcolm Messiter “simplified” the whole paradox by just making their own Teensy-powered transmitter and receiver from scratch.

The transmitter uses a Teensy 4.1, and the receiver a 4.0, both equipped with a Nordic nRF24L01+ 2.4GHz transceiver, providing a range of approximately 2.5km! The current firmware supports 16 channels, 12-bit servo resolution, four flight modes, 32 mixes, 99 model memories with import and export, FHSS (Frequency Hopping Spread Spectrum), PWN and SBUS output, failsafe on any channel, digital trims and graphic curves on all channels, and user-defined channel names. All of this is managed via a GUI on a Nextion color touch screen. Binding is via a 64-bit ID for maximum security. These features dramatically exceed the specs of many high-end radio systems costing hundreds, or even thousands of dollars, and are demonstrated effortlessly controlling an SAB Urukay in the video below.

Video Control Surface

YouTuber Zack Freedman wanted to improve his video-editing workflow without spending $100s on new hardware, so he grabbed a Teensy and committed to a one-weekend time limit over which to build his own control surface.

Essentially three normal and one giant knob plus a weird mechanical keyboard, the project is mostly 3d-printed beyond these components, supporting passives, and basic hardware. Source code, design files, and BOM can be found on GitHub, while the accompanying video not only shows you how to put it all together, but also provides a slew of great tips for successful rapid prototyping.

Knife Throwing Machine

Quint BUILDs is known for impressive, entertaining YouTube videos. Having previously relied on Arduino boards for microcontroller projects, his Knife Throwing Machine presented a new challenge due to the real-time calculations required to launch a knife at exactly the right trajectory for it to nail its target tip-first.

This is where the Teensy 4.1 came to the rescue, in order to provide the 18,000 steps per second required by the motors in use. See the resulting insanity in action in the video below, and then go behind the scenes in the video below that.

Breadboard Drum Machine

Sebastian Tomczak, aka little-scale, has built a homemade drum machine around the Teensy 3.6, entirely on a solderless breadboard!

Sixteen button/LED pairs for step sequencing, two 74HC595 shift registers, five further buttons/LEDs for drum/pattern selection and pattern length, and a potentiometer for tempo control are all intricately wired to a pair of large breadboards.

The four channels provide kick, snare, noise-generated hi-hat, and percussive synth samples. Each voice has sixteen steps and four patterns. Each sample channel has 16 samples to select from, and a low-pass resonant filter tailors the overall output. Nanoloop, Pocket Operator, and Sync 24 (DIN sync) help it play nice with other gear. Learn more on the little-scale blog, and check it out in action in the video below!

Tektronix DPO USB Interface

1973’s Tektronix Digital Processing Oscilloscope (or “DPO” for short) was comprised of a 7704A ‘scope and a P7001 digitizer, processor, and memory unit. The processing unit could in turn be connected to an external computer, such as the PDP–11 16-bit minicomputer from Digital Equipment Corporation.

This would have been a dream setup in the 1970s, but in the modern era, the chances of finding a working PDP-11 hanging around to plug your old ‘scope into are rather rare. Which is why Holger Lübben designed the Teensy 4.1-based USB+ Interface, to replace the slow GPIB interface (which was limited to about 50 data words per second) and allow direct connection to a modern PC over USB.

The USB+ Interface is connected directly to the internal bus of the P7001 unit, allowing interaction with every aspect of the instrument, including other plug-in cards. Level shifters facilitate interaction with the 5V system. The software-controlled X/Y mode of the P7001 allows arbitrary vectors to be drawn on the ‘scope, which Holger used to create an on-screen menu to help navigate custom software, such as demos, calibration tools, and even a joke of the day. Extensive detail about the project including pictures, documentation and further resources can be found on the project’s web page.

Original Xbox Controller to USB

There may not be many fans of the original Xbox controller (aka “The Duke”), but Tom Mason, aka wheybags on GitHub, is a big enough fan to take on the task of dragging the infamous behemoth into another generation of gaming with this USB adapter.

Based on the Teensy 4.1, the adapter simply connects an Xbox extension cable to the Teensy’s USB host pins, and then plugs into a PC via USB. By patching the Teensy 3.x ArduinoXInput_Teensy library to work on 4.x, Tom then brought the necessary XInput USB mode to the device, allowing it to appear as a normal Xbox 360 controller to the PC. Tom has a nice blog post detailing the trials and tribulations involved, and the firmware and FreeCAD file can be found in the project’s GitHub repo.