Teensy

More speed and power than you ever thought possible in a microcontroller.

Teensy is a compact USB-based microcontroller development system that supports a wide range of projects and is programmed entirely through the USB port.

Teensy 4.1

Teensy 4.0

Teensy 4.1

Models Available

Video Overview

Feature	Teensy 4.1
Processor	ARM Cortex-M7 at 600 MHz
Ethernet	10 / 100 Mbit DP83825 PHY (6 pins)
USB Host	5 Pins with power management
SDIO (4 bit data)	Micro SD Socket
PWM Pins	35
Analog Inputs	18
Serial Ports	8
Flash Memory	8MB
QSPI Memory	2 chips + Program Memory
Breadboard I/O	42
Bottom SMT Pads	7
SD Card Signals	6
Total I/O Pins	55

Full Specs

ARM Cortex-M7 at 600 MHz
Float point math unit, 64 & 32 bits
7936K Flash, 1024K RAM (512K tightly coupled), 4K EEPROM (emulated)
QSPI memory expansion, locations for 2 extra RAM or Flash chips
USB device 480 Mbit/sec & USB host 480 Mbit/sec
55 digital input/output pins, 35 PWM output pins
18 analog input pins
8 serial, 3 SPI, 3 I2C ports
2 I2S/TDM and 1 S/PDIF digital audio port
3 CAN Bus (1 with CAN FD)
1 SDIO (4 bit) native SD Card port
32 general purpose DMA channels
Cryptographic Acceleration & Random Number Generator
RTC for date/time
Programmable FlexIO
Pixel Processing Pipeline
Peripheral cross triggering
Power On/Off management

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Teensy 4.0

Models Available

Video Overview

Feature	Teensy 4.0
Processor	ARM Cortex-M7 at 600 MHz
Ethernet	-none-
USB Host	2 SMT Pads
SDIO (4 bit data)	8 SMT Pads
PWM Pins	31
Analog Inputs	14
Serial Ports	7
Flash Memory	2MB
QSPI Memory	Program memory
Breadboard I/O	24
Bottom SMT Pads	16
SD Card Signals	0
Total I/O Pins	40

ARM Cortex-M7 at 600 MHz
Float point math unit, 64 & 32 bits
1984K Flash, 1024K RAM (512K tightly coupled), 1K EEPROM (emulated)
USB device 480 Mbit/sec & USB host 480 Mbit/sec
40 digital input/output pins, 31 PWM output pins
14 analog input pins
7 serial, 3 SPI, 3 I2C ports
2 I2S/TDM and 1 S/PDIF digital audio port
3 CAN Bus (1 with CAN FD)
32 general purpose DMA channels
Cryptographic Acceleration & Random Number Generator
RTC for date/time
Programmable FlexIO
Pixel Processing Pipeline
Peripheral cross triggering
Power On/Off management

Download Full PDF

Additional Teensy Specifications

Software
Arduino IDE + Teensyduino
- Arduino's IDE software with the Teensyduino add-on is the primary programming environment for Teensy. On Windows, Linux and old Macs, Arduino is installed first and then the Teensyduino installer adds Teensy support to the Arduino IDE. On newer Macs, an all-in-one download is provided. Teensyduino includes a large collection of libraries which are tested and optimized for Teensy. Other libraries may be installed manually or by Arduino's library manager.
Visual Micro
- Visual Micro allows use of Microsoft Visual Studio to program Arduino compatible boards, including Teensy. Only Windows is supported. Visual Micro is commercial paid software.
PlatformIO
- PlatformIO IDE is a cross platform development environment with many advanced features. Windows, Linux and Macintosh are supported.
CircuitPython
- CircuitPython provides a .HEX file which you program onto Teensy 4.1 using Teensy Loader. Then Teensy appears to your computer as a USB disk, where copy or save your Python code. CircuitPython does not fully support all of Teensy 4.1's hardware.
Command Line with Makefile
- Makefiles for non-graphical use are provided with the Teensyduino installer.
  - Teensy 4.x: {Arduino}/hardware/teensy/avr/cores/teensy4/Makefile
  - Teensy LC & 3.x: {Arduino}/hardware/teensy/avr/cores/teensy3/Makefile
Processor
Performance
- ARM Cortex-M7 brings many powerful CPU features to a true real-time microcontroller platform. CPU performance is many times faster than typical 32 bit microcontrollers.
Dual Issue Superscaler Architecture
- Cortex-M7 is a dual-issue superscaler processor, meaning M7 can execute 2 instructions per clock cycle, at 600 MHz! Of course, executing 2 simultaneously depends upon the compiler ordering instructions and registers. Initial benchmarks have shown C++ code compiled by Arduino tends to achieve 2 instructions about 40% to 50% of the time while performing numerically intensive work using integers and pointers.
Floating Point Unit
- The FPU performs 32 bit float and 64 bit double precision math in hardware. 32 bit float speed is approximately the same speed as integer math. 64 bit double precision runs at half the speed of 32 bit float.
Tightly Coupled Memory
- Tightly Coupled Memory is a special feature which allows Cortex-M7 fast single cycle access to memory using a pair of 64 bit wide buses. The ITCM bus provides a 64 bit path to fetch instructions. The DTCM bus is actually a pair of 32 bit paths, allowing M7 to perform up to 2 separate memory accesses in the same cycle. These extremely high speed buses are separate from M7's main AXI bus, which accesses other memory and peripherals.
Cache
- Two 32K caches, one for instructions and one for data, are used to speed up repetitive access to non-TCM memory.
Branch Prediction
- Cortex-M7 is the first ARM microcontroller to use branch prediction. On Cortex-M4 & earlier, loops and other code which much branch take 3 clock cycles. With M7, after a loop has executed a few times, the branch prediction removes that overhead, allowing the branch instruction to run in only a single clock cycle.
Digital Signal Processing
- DSP extension instructions accelerate signal processing, filters and Fourier transform. The Audio library automatically makes uses of these DSP instructions.
Digital Pins
Digital Input Pins
- Digital pins may be used to receive signals. Teensy 4.1 pins default to INPUT most with a "keeper" resistor. Teensy 4.1 pins accept 0 to 3.3V signals. The pins are not 5V tolerant. Do not drive any digital pin higher than 3.3V.
Input Pullup / Pulldown / Keeper Resistors
- All digital pins have optional pullup, pulldown, or keeper resistors. These are used to keep the pin at logic HIGH or logic LOW or the same logic level when it is not being actively driven by external circuity. Normally these resistors are used with pushbuttons & switches. The pinMode function with INPUT_PULLUP or INPUT_PULLDOWN must be used to configure these pins to input mode with the built-in resistor.
Pin Change Interrupts
- All digital pins can detect changes. Use attachInterrupt to cause a function to be run automatically. Interrupts should only be used for clean signals. The Bounce library is recommended for detecting changes on pushbuttons, switches, and signals with noise or mechanical chatter.
Digital Output Pins
- All digital pins can act at output. The pinMode function with OUTPUT or OUTPUT_OPENDRAIN must be used to configure these pins to output mode. The digitalWrite and digitalToggle functions are used to control the pin while in output mode. Output HIGH is 3.3V. The recommended maximum output current is 4mA.
Pulse Width Modulation (PWM)
- 35 of the digital pins support Pulse Width Modulation (PWM), which can be used to control motor speed, dim lights & LEDs, or other uses where rapid pulsing can control average power. PWM is controlled by the analogWrite function. 22 groups of PWM can have distinct frequencies, controlled by the analogWriteFrequency function.
Slew Rate Limiting
- This optional feature greatly reduces high frequency noise when long wires are connected to digital output pins. The rate of voltage change on the pin is slowed. The extra time is only nanoseconds, which is enough to lower undesirable high frequency effects which can cause trouble with long wires.
Variable Drive Strength
- The output impedance of each digital output may be controlled in 7 steps, ranging from 150 ohms (weakest) up to about 21 ohms (strongest).
Adjustable Output Bandwidth
- Digital output bandwidth is also programmable, in 4 steps: 50, 100, 150 and 200 MHz.
LED Pin
- Pin 13 has an orange LED connected. The LED can be very convenient to show status info. When pin 13 is used as an input, the external signal must be able to drive the LED when logic HIGH. pinMode INPUT_PULLUP should not be used with pin 13.
Analog Pins
Analog Inputs
- 18 pins can be used an analog inputs, for reading sensors or other analog signals. Basic analog input is done with the analogRead function. The default resolution is 10 bits (input range 0 to 1023), but can be adjusted with analogReadResolution. The hardware allows up to 12 bits of resolution, but in practice only up to 10 bits are normally usable due to noise. More advanced use is possible with the ADC library.
Analog Range
- The analog input range is fixed at 0 to 3.3V. On Teensy 4.1, the analogReference() function has no effect. The analog pins are not 5V tolerant. Do not drive any analog pin higher than 3.3 volts.
Analog Comparators
- These comparators allow an analog signal to be converted to digital, with a precisely defined voltage threshold for logic low versus high.
Communication
USB Device

Teensy's primary communication is its main USB port, which operatates in USB device / peripheral mode at 480 Mbit/sec speed. The Teensyduino software supports many different types of USB communication to your PC or Mac, selected by the Tools > USB Type menu. Several of these devices types may be used simultaneously.
- Serial - Seen by your computer as a COM port (Windows) or serial device (Mac, Linux), Serial is the default and most commonly used communication type. Bytes are transfered in both directions at maximum USB speed (baud rate settings are ignored). Teensyduino has highly optimized code to allow fast USB serial data transfer. While normally used with the Arduino Serial Monitor, Teensy's USB Serial mode is compatible with software designed for serial ports, like CoolTerm. On Teensy, the seraild devices is accessed as "Serial". In the Dual & Triple Serial modes, the additional serial devices are "SerialUSB1" and "SerialUSB2".
- Emulated Serial - The USB Type settings lacking Serial use a HID interface to emulate serial. In these modes, your PC or Mac will not detect a COM port or serial device, but you can still use Serial.print() to send text to the Arduino Serial Monitor.
- MIDI - Musical Instrument Device. MIDI is often used to interface knobs, sliders and buttons to music & sound control software. MIDI messages may be sent in both directions. Teensyduino's MIDI is "class compliant" for compatibility with Macintosh, Linux, and Windows using only built-in drivers. The MIDIx4 & MIDIx16 modes provide 4 or 16 virtual MIDI ports / cables. The MIDI device name seen by your computer may be customized.
- Audio - Bi-directional stereo audio streaming, seen by your computer as a USB sound card. Using your computer's sound preferences, programs which play sound can stream to Teensy, and programs which record or process sound can receive, as if you were using a USB microphone. USB Audio is meant to be used together with the Teensy Audio Library, allowing your computer's sound to integrate with any audio processing system you design on Teensy.
- Keyboard - Standard 104 key USB keyboard. Programs can transmit keystrokes to your computer, allowing control of nearly any software. Media control keys (play, pause, volume, etc) may also be used. Many non-US keyboard layouts are supported, using the Tools > Keyboard Layout menu.
- Mouse - A special USB mouse is emulated. Both relative motion of a normal mouse, and absolute screen position similar to a digitizer pen can be sent to your computer. Mouse buttons and scroll wheel are also supported.
- Joystick - A joystick / game controller with 6 axes (X, Y, Z, Zr, Slider1, Slider2), 32 buttons, and 1 hat switch are supported. The Joystick type is useful for controlling games or other software which responds to a joystick.
- Touchscreen - Emulates a touchscreen capable of detecting up to 10 finger positions.
- MTP Disk - Media Transfer, seen by your computer as a phone or camera which shares files.
- Flight Sim - Allows integration with the X-Plane flight simulator software. Variables and controls within the simulator are linked to variables in your code running on Teensy.
- Raw HID - Allows communicating 64 byte messages with custom written software on your computer.
Serial
- 8 serial ports allow you to connect serial devices, such as MIDI, GPS receivers, DMX lighting, ESP wireless modules, etc. All 8 serial ports are fully independent and can transfer data simultaneously. None are shared with USB (as is done on some Arduino boards). All 8 ports include FIFOs for better performance at high speed baud rates.
I2C
- 3 ports for I2C (signals SDA & SCL) allow connecting a wide variety of chips which use I2C communication. The Wire library is used for I2C. Each I2C chip connected to the same SDA/SCL wires needs a unique address. Multiple I2C ports allow you to easily use more than 1 chip with the same address. All I2C ports support 100, 400, and 1000 kbit/sec speeds.
SPI
- 3 ports for SPI (signals MOSI, MISO, SCK) allow connecting higher speed chips, SD cards, and displays which use SPI communication. The SPI library provides software support for SPI. The first SPI port features a FIFO for higher sustained speed transfers. Each SPI chip requires a chip select (CS) signal. Most libraries using SPI can use any digital pin. The SPI ports provide special hardware controlled CS pins, which are used by specially optimized libraries for higher performance.
CAN
- 3 ports for CAN bus allow connecting to automotive & industrial control systems which use CAN communication. A CAN transceiver chip must be added to complete the electrical interface between Teensy 4.1 and the CAN bus.
FlexIO
- FlexIO is a highly configurable peripheral, with a sort of build-your-own ports from a collection of shift registers, timers, logic and state machines. FlexIO can implement UARTs (serial), I2C, SPI, I2S audio, PWM. Unique interfaces can also be built, such as the TriantaduoWS2811 library.
Ethernet (Teensy 4.1 only)
- Teensy 4.1 contains an Ethernet controller and Ethernet PHY chip. To connect an Ethernet cable, only this RJ45 magjack kit is needed. Ethernet can also be implemented using the Wiznet W5500 and Wiz820 shield, connected to the SPI port.
Power
USB Power
- Normally Teensy is powered by your PC or USB hub, through a USB cable. The USB power arrives at the VUSB pin, which is connected VIN and powers the entire board.
VIN Pin
- When USB power is not used, 5V power may be applied to the VIN pin. Because VIN & VUSB are connected, power should not be applied to VIN while a USB cable is used, to prevent the possibility of power flowing back into your computer. Alternately, a pair of pads on the bottom side may be cut apart, to separate VUSB from VIN, allowing power to be safely applied while USB is in use. (TODO: VUSB-VIN pads photo, right side)
3.3 Power
- Teensy 4.1 has a voltage regulator which reduces the 5V VUSB / VIN power to 3.3V for use by the main processor and most other parts. Additional circuitry may be powered from the 3.3V pin. The recommended maximum for external 3.3V usage is 250mA. Teensy 4.1 is not meant to receive power on its 3.3V pin, but this can be done with special modificaton.
USB Host Hot Plugging
- Power to USB devices connected on the USB host port is provided through a current limited switch and a large capacitor. The current limit lessens the disruption to Teensy's power when a USB device is hot plugged and needs a sudden inrush current to charge up all its capacitors.
Power Consumption
- When running at 600 MHz, Teensy 4.0 consumes approximately 100 mA current. Reducing CPU speed to 528 MHz or lower reduces power consumption.
Low Power Features
- Snooze library
CPU Voltage Control
- A DC-DC buck converter creates lower voltage needed for the CPU. Software can control this voltage, in 50 mV steps. At 600 MHz, the CPU runs on 1.25V. For 528 MHz and lower, 1.15V is used. At 24 MHz, the CPU runs on only 0.95 volts. When overclocking, higher voltages are automatically used.
VBAT
- A 3 volt coin cell may be connected to VBAT & GND to allow the RTC to keep track of date / time while power is off. A CR2032 type battery is recommended, though other 3V coin cells may also be used.
On/Off Pin and Power Control
- A special low power state which turns off the 3.3V power can be controlled by the On/Off pin. A pushbutton is meant to be connected between On/Off and GND. While running, holding the button for 4 seconds turns off power. Pressing for 0.5 seconds while power is off turns the 3.3V power back on and reboots the processor. If a coin cell is connected to BVAT, the power state is retained when main power is disconnected. Without VBAT, the power state always defaults to 3.3V power on, even if the On/Off button had been used to turn off 3.3V before main VIN/VUSB power was removed.