Teensy 3.1 is a small, breadboard-friendly development board designed by Paul Stoffregen and PJRC. Teensy 3.1 brings a low-cost 32 bit ARM Cortex-M4 platform to hobbyists, students and engineers, using an adapted version of the Arduino IDE (Teensyduino) or programming directly in C language. Teensy 3.1 is an upgrade over 3.0: now with 64K of RAM, 256K of Flash, 5V tolerant digital inputs, 12 bit DAC, dual ADC, and CAN bus support.Based on a 32 bit ARM chip, Teensy 3.1 aims to greatly increase the computing capability and peripheral features. 

Technical Specifications:

• 32 bit ARM Cortex-M4 72MHz CPU
  
• 256K Flash Memory, 64K RAM, 2K EEPROM
  
• 21* High Resolution Analog Inputs (13 bits usable, 16 bit hardware)
  
• 34* Digital I/O Pins (21 shared with analog)
  
• 12 PWM outputs
  
• 1 12-bit DAC output
  
• 8 Timers for intervals/delays, separate from PWM
  
• USB with dedicated DMA memory transfers
  
• CAN bus
  
• 3 UARTs (serial ports)
  
• SPI, I2C, I2S, IR modulator
  
• I2S (for high quality audio interface)
  
• Real Time Clock (with user-added 32.768 crystal and battery)
  
• 16 general purpose DMA channels (separate from USB)
  
• Touch Sensor Inputs
  

Datasheet