The Teensy 3.5 is one of the most powerful Arduino compatible microcontroller on the market in a very small factor (beside the Teensy 3.6). If you own a Teensy 3.2, you will probably want to purchase this one; it is faster than the Teensy 3.2, you've got more I/O and more RAM and furthermore, you can store you data directly on a microSD card. And this is not all, please see features!

If you are familiar with Arduino, you'll feel at home with Teensy; download Arduino's IDE and install Teensy plugin on top of it from PJRC website and you are ready to go and create your first Sketch. Teensy is probably the best Arduino alternative on the market right now.

Features

MCU: NXP Kinetis K64 ARM Cortex M4 MCU @ 120 MHz with FPU, 512KB flash, 192 KB RAM, 4K EEPROM
storage: micro SD card port
USB: 1x USB Full Speed (12 Mbit/sec)
connectivity: 10/100M Ethernet mac
62x I/O Pins (42 breadboard friendly)
25x Analog Inputs to 2 ADCs with 13 bits resolution
2x Analog Outputs (DACs) with 12 bit resolution
20x PWM Outputs
6x Serial Ports (2 with FIFO & Fast Baud Rates)
I2S Audio Port, 4 Channel Digital Audio Input & Output
3x SPI Ports (1 with FIFO), 4x I2C Ports
CAN bus: 1x
14x Hardware Timers
General Purpose DMA channels: 16x
security: Cryptographic Acceleration Unit, Random Number Generator, CRC Computation Unit
misc.: Real Time Clock; 5V tolerance on all digital I/Os