Also known as: Teensy
Teensy is a line of compact, high-performance microcontroller boards made by PJRC, built on ARM Cortex-M cores.1
Overview
The flagship Teensy 4.0 and 4.1 run a 600 MHz Cortex-M7 — far faster than a typical hobby MCU — in a board barely larger than a postage stamp. Teensy boards are Arduino-compatible through the Teensyduino add-on, so they use familiar libraries and the Arduino IDE, but they also expose deep hardware features: many GPIO pins, several UART/SPI/I²C buses, PWM, and strong USB support.
PJRC, the small Oregon company behind Teensy, is also known for a polished audio library that turns the boards into capable real-time signal processors — a large part of their following.
Teensy 4.x versus a classic board
The gap in raw capability is stark:
| Spec | Arduino Uno | Teensy 4.0 |
|---|---|---|
| Core | 8-bit AVR | 32-bit Cortex-M7 |
| Clock | 16 MHz | 600 MHz |
| Flash | 32 KB | 2 MB |
| RAM | 2 KB | 1 MB |
| FPU / DSP | No | Yes |
Where it fits
Teensy is the go-to when an Arduino-style workflow needs serious horsepower or precise timing. Its well-known audio library makes it a favorite for synthesizers and effects, and its fast cores suit MIDI controllers, data loggers, and other real-time work. Where a project wants the same class of compute with vendor tooling instead of the Arduino layer, an STM32 is the usual alternative. Its DSP-capable core and audio pipeline also make it a plausible front-end for light real-time signal work near an SDR setup — though full trunking decode still belongs on a general-purpose host.