Teensyduino 1.60 Released

Teensy software 1.60 has been released. Arduino IDE 2 should automatically detect the new version and give a single click update.

For Arduino IDE 1.8.x, you must download and run the special installer.

In this article we’ll take a quick look at the new features and many bug fixes and small improvements 1.60 brings.

16MB PSRAM Chip

The new 16MB PSRAM chip available from ProtoSupplies (full part number IS66WVS16M8FBLL-104NLI) is now officially supported. Previously only an 8MB chip was supported.

You can solder 1 or 2 of these 16MB chips to the bottom side of Teensy 4.1 to expand its memory. ProtoSupplies also sells Teensy 4.1 with these chips soldered.

Larger PSRAM memory is particularly useful for polyphonic sample-based musical synthesis (demo video) and fast data logging applications which need a large buffer to deal with ongoing data collection while experiencing SD card or network latency.

The default clock speed for external memory is also increased by 1.60, so either 8MB or 16MB chips will perform faster than with prior versions.

Jonathan Oakley deserves credit for much of the work to support this new chip.

Lockable Teensy in Arduino IDE 2

Using Lockable Teensy involves running 3 programs to initialize the hardware with your encryption key. Once initialized, it can be used as normal where all programming is done with encrypted .ehex rather than a normal .hex file.

Generating the initialization programs previously required using Arduino 1.8.19, or command line utilities, because Arduino 2.x.x doesn’t support the Java-based plugins from older Arduino IDE.

Version 1.60 brings this plugin to Arduino IDE 2.x.x using the Typescript plugin system.

One unfortunate side effect is an empty “Teensy 4 Security” menu appears. This is a bug Arduino IDE 2 inherits from Theia IDE. It has been assigned Arduino IDE issue #2848. Hopefully future Arduino IDE will fix this issue.

Wire Slave Mode on Teensy 4

Wire slave mode, where Teensy acts as a I2C peripheral, has been improved.

A common I2C usage is a write transaction followed by a read transaction which uses repeated start, so the entire write-then-read operation is a single usage of the I2C bus. Previously the onReceive() and onRequest() functions would be called in the wrong order. 1.60 fixes handling of repeated start, so onReceive() is called first, which allows your program to make use of the info received when onRequest() is called.

Slave mode now uses a glitch filter which prevents noise coupled to the SDA and SCL lines from disrupting communication. This problem was discovered by an application transmitting digital audio data and I2C control between boards, where the audio clock signal could interfere.

Use of Teensy 4.x in as an I2C slave device should be more reliable with version 1.60.

SoftwareSerial on Teensy 4 and Teensy 3

SoftwareSerial is finally fully supported on all Teensy boards.

For new projects on Teensy 4, you can achieve many more serial ports with FlexIO_t4 FlexSerial which creates more ports with hardware-based FlexIO. SoftwareSerial support is mainly meant for compatibility with Arduino sketches written for Arduino Uno.

Previously on Teensy 3 and Teensy 4, SoftwareSerial was just a thin abstraction which used real hardware serial ports. It only worked if you chose the pins of an actual serial port. This allowed programs written for Arduino Uno to work with only minor edit and choosing different pins. Now those program can work “out of the box”.

The new implementation on Teensy 3 and Teensy 4 uses pin and timer interrupts to receive, so it doesn’t block the CPU for other interrupts like SoftwareSerial on most other boards. 10 interrupts per received byte is less efficient than only 1 with FlexSerial or less with regular serial which uses a hardware FIFO, but a huge improvement compared to blocking all interrupts for the duration of the incoming byte.

USB Keyboard NKRO

Teensy USB Keyboard mode can now support all-keys NKRO communication to your PC.

Traditional 6 key mode is still the default, for maximum compatibility with PC bios and KVM switches. To enable NKRO mode, you must edit usb_desc.h within the core library. Simply change KEYBOARD_SIZE to 16 for all-keys NKRO.

NKRO mode uses 1 bit for every key, so any combination of any number of keys may be pressed simultaneously. This can be useful for controlling music synthesis software and video games.

Bug Fixes and Updates

HardwareSerial XBAR pins 7, 8, 36 on Teensy 4 fixed thanks to KurtE
HardwareSerial receive with setRX fixed on Teensy 4 thanks to sndsgd
HardwareSerial serialEvent fixed on Teensy 3
digitalWriteFast() now check for valid pin number in non-const pin case
Fix extmem_realloc with NULL on Teensy 4.1
Fix __SSAT return type
FS class now has virtual destructor
Audio fix TDM2 input and output thanks to Jonathan Oakley
Audio fix stuck AudioEffectFade with no input thanks to Jonathan Oakley
Audio fix AudioEffectFreeverbStereo thanks to Synvox
Audio fix AudioSynthToneSweep buffer overflow thanks to Steven Hazel
Audio improve AudioEffectReverb thanks to Eric Brombaugh
Audio fix for Teensy LC code thanks to Mark Tillotson
Teensy Loader waits longer for large flash erase
Suppress pointless C++ ABI warnings
Fix erroneous “Teensy should be selected from teensy ports” message
Audio effect envelope: don’t re-start release if noteOff() called, thanks to Jonathan Oakley
Audio effect granular: add guard macros, thanks to Jonathan Oakley
Audio effect reverb: fix reverb cut off when incoming data stops, thanks to Jonathan Oakley
Improve Teensy Loader toolbar icons on Windows
Fix Teensy Loader toolbar on MacOS
SD Improve SDIO media presence detection
SdFat SPI driver avoid 512 byte stack usage, thanks to KurtE
LittleFS update Fujitsu FRAM, thanks to mjs513
SerialFlash fix use of alternate SPI ports, thanks to KurtE
ST7735_t3 support 320×480, thanks to KurtE
ST7735_t3 fix colors with setRotation(2), thanks to Jonathan Oakley
USBHost_t36 KeyboardController delete debug messages, thanks to Tristan Rowley
Fix DMA TCD copy out of order by compiler optimization, thanks to jmarsh
FS class and LittleFS use constexpr constructor
Improve PLL PFD setup, hopefully fixes weird crashes, removes need for startup hacks
Fix AudioMemory with optimize Smallest Code with LTO
DMAChannel default channel preemption settings
SdFat examples recommend at most 25 MHz for SPI
CrashReport minor changes to printed message, thanks to Shawn Silverman
USB Keyboard define GUI key names
USB MIDI receive return channel=0 for system messages
USBHost_t36: recover from device errors during enumeration
Libraries updated: ST7735_t3, FlexIO_t4, ILI9488_t3, LittleFS, QuadEncoder, ShiftPWM

Build Process and MacOS Support

The systems used to build Teensy software have been updated. Teensy Loader is now built with wxWidgets 3.2.6, rather than a variety of very old versions different to each operating system.

Much of this change was needed because of changes in application signing practices for Windows and MacOS. For Windows, code signing certificates are now issued only by hardware keys. For MacOS, Apple discontinued notarization from older versions of X-code, effectively blocking older Macs.

One unfortunately side effect is we had to discontinue supporting old Arduino IDE 1.8.x on MacOS. Teensyduino still full supports use of Arduino IDE 2.x.x on MacOS.

Support for Linux i686 (32 bit Intel X86) was also dropped.

While these changes drop support for old systems, the updated build process uses newer toolchains which should give better long-term support than the older software used to build all prior Teensy software.

3D Rendering

The PJRC forums are a great place to collaborate, share, and learn. It’s incredible to watch projects evolve and members learn from each other, and often even we are blown away with some of the things folks do with Teensy.

Case in point: JarkkoL’s port of their tiled software rasterizer. JarkkoL’s initial port targeted the ILI9341 LCD driver at 320x240x16 bits per pixel (bpp) via SPI, with 16bpp frame and depth buffers. Running on a Teensy 3.6, the rasterizer uses just 27kb of RAM, with 4,000 triangles stored in flash. As the thread unfolds over a little under two months, more and more enhancements are added, including asynchronous DMA transfer, cluster visibility culling, and texture support.

A port to Teensy LC was accomplished in just 8kb, and the Teensy 4.0 port pushed 16bpp updates at 49 frames per second. We hope to see these examples developed into a full library soon!

Constructive Synthesis Book

We have a lot of Teensy enthusiasts, especially in areas like audio synthesis, some with such passion and knowledge, you might say they could write a book on it. In the case of Ken Wessen, this is literally the case, in the form of the web-based book Constructive Synthesis.

In addition to comprehensive coverage of subtractive synthesis topics, the site also includes over 30 web apps that allow the reader to experience concepts first hand, as well as ten projects for the Teensy 4.0 + Audio Adaptor Board. The projects culminate in the creation of Mentor, a 16-voice polyphonic Teensy-based synth, optimized for learning subtractive synthesis and patch creation. Start learning how to make your own Teensy-based synth today, and be sure to let Ken know if you have feedback or suggestions!

ProtoTracer – 3D Rendering Engine

When games like Wolfenstein 3D debuted in the early 90s, their raycasted 3D graphics seemed like a dramatic leap forward compared to most side-scrolling games of the time.

Fast forward three decades, and most mobile phones have powerful 3D accelerators that make games from even a few years ago look unsophisticated. But PJRC forum member coelacant1 has brought back this classic software rendering technique with a custom rendering engine for the Teensy 4.0. Rather than rendering 3D objects on a monitor, coelacant1’s ProtoTracer is designed for use with LED matrices, such as those found in their own line of LED masks. Converters for 3D FBX and OBJ files, as well as 2D PNGs, BMPs, JPEGs and more allow the rendering and animation of numerous assets on arbitrary LED hardware. Source code and instructions, as well as links to the aforementioned conversion tools can all be found in the project’s GitHub repo.

Magic Dice Box

The annual YouTube Makers Secret Santa has resulted in all manner of creative and exciting projects being created as gifts between its high-profile participants, and 2024’s was no exception.

DJ Harrigan, aka Mr. Volt drew Crescent Shay, which was a fortuitous pick given that they are already friends who play Dungeons & Dragons together. This lead to the idea of a dice box, to hold and display Shay’s dice collection, but with an added Teensy 3.5-powered twist.

In addition to the “analog” dice tower to facilitate rolls, Harrigan incorporated a digital dice roller via an LCD screen and two rotary encoders. Sound effects are also played via a DAC and the Teensy’s mSD card. Lastly, the Teensy illuminates the analog dice storage area with LEDs for a little extra pizazz. See it all in action in the video below!

8×14 1U MIDI and Audio Interface

DeftAudio, aka Andrei Kudryavtsev has created an 8×14 1U MIDI and Audio Interface based on the Teensy 4.1.

With 8×8 5-pin MIDI DIN in/out, plus six MIDI TRS outs (which can also be configured as 5V Trigger out or Sync out for controlling Eurorack modular gear, drum machines, or analog synthesizers), as well as USB MIDI and a 2×2 audio interface, which seems almost absurd for a kit that starts at $25 for the main PCB. An OLED display and two rotary encoders provide the interface.

Best of all the project is completely open-source, with schematics, firmware, and even the enclosure available on GitHub. The “Complete Electronics” kit (bring your own Teensy and front panel) is just $40, while the fully assembled model will set you back $225 — still a steal for this level of functionality. Check out the video below, then head over to Tindie to pick up a kit!

Reverse-Engineered Seat Heater Switches

Alex Lorman had two things: a 2006 4Runner and a desire for year-round posterior comfort. So he picked up some OEM switches. And some commodity seat heaters. And a whole bunch of knowledge along the way!

The project culminated in a custom PCB, primarily as a home for the MOSFETs required to drive 10A per channel to the heaters. And to manage state and the MOSFETs, a Teensy 3.2 was employed.

One interesting aspect of the project was the employment of low-rate PWM to allow the MOSFETs to avalanche while capitalizing on the high resistance of the heated heaters to enable self-regulation. A GitHub repository serves as a clearing house for information and resources related to the product, with two further repos for the PCB and code.

CB Desk Mic

Jigglypuff works in a noisy office, and wanted to avoid the complaints that their built-in laptop mic was garnering during Teams meetings.

Instead of juggling muting in the software itself, they converted a vintage Turner CB desk mic into a digital USB microphone using Teensy 4.0.

After an initial prototype proved unsatisfactory, Jigglypuff switched to the Teensy Audio Shield and a PUI AOM-5024 series electret condenser mic. Unfortunately, the Teensy Audio Shield would not fit inside the Turner, leading to the creation of a custom shield without unwanted features like the mSD slot and line in/out. The final device features push-to-talk with an LED if the mic is active, a pot for mic gain adjustment, a 125Hz high-pass filter, and the all-important ability to present itself as a microphone, not a full-duplex sound card (since it has no output capabilities). Pretty impressive for someone who claims “EE and software is not my primary background.” Learn more and follow the journey in the PJRC forum thread.

Drone 2.0 Eurorack Synth Module

Long-time PJRC forum contributor ghostintranslation is back with a new version of the Drone Eurorack module, dubbed Drone 2.0 for its basis on the updated Motherboard 2.0 platform.

The module features four voices with sine and resonant noise oscillators, FM control voltage (CV), individual volts per octave, and a TRS MIDI.

The Motherboard platform underpinning all this was designed to facilitate the creation of new modules, without having to start from scratch every time, and itself features 16 inputs and outputs, MIDI in/out, 10-pin Eurorack power, and Teensy 4.0-based firmware and examples.

Drone 2.0 is available as a PCB/panel kit with SMD components prepopulated. The required BOM, as well as firmware and schematics, can be found in the project’s GitHub repo. Listen to example sounds below!

Audio Keyword Recognition

In addition to our standard form-factor boards, Teensy is available as a member of SparkFun’s MicroMod range of M.2 mix-and-match processors. Maker Evan Rust selected this board to pair with SparkFun’s MicroMod Machine Learning Carrier for a simple yet powerful keyword recognition project.

Using publicly available datasets, Evan uploaded clips of half a dozen keywords to Edge Impulse, along with “noise” samples, and trained a Keras neural network with 92.7% recognition accuracy. Combining the resultant Arduino library generated by Edge Impulse with Teensy’s Audio Library, then downsampling from 44.1KHz to 16KHz in order to match the dataset’s samples, the inference results are displayed on an ILI9341-driven TFT in real time as a bar graph of sorts reflecting the model’s confidence. A detailed walk-through of how to recreate the project can be found on Hackster.

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