Teensy is a line of hardware boards designed to offer maximum I/O capabilities, backed up by a slew of fully featured software libraries designed to run on Arduino. The Teensy is a complete USB-based microcontroller development system, in a very small footprint, capable of implementing many types of projects. All programming is done via the USB port. The Teensy boards are fully compatible with Arduino Software & Libraries.
Most programs written for Arduino work on Teensy. All of the standard Arduino functions (digitalWrite, pinMode, analogRead, etc) all work on Teensy. Teensy has the same built-in peripherals as the Arduino: analog inputs, SPI, I2C, PWM, and a real serial port. For applications that need the serial port (MIDI, GPS modules, etc), Teensy is very easy to use, because uploading takes place on the USB port, which is not shared with serial.
All of our Teensy breakout boards are designed for projects that require Controller Area Network (CAN Bus), CAN FD, and SAE J1939.