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Teensy 3.1 - New Features

Teensy 3.1

Teensy 3.1 has gold plating for easier soldering.

Teensy 3.0

Teensy 3.0 has standard tin plating finish.
Teensy 3.1 has the same size, shape & pinout; is compatible with code written for Teensy 3.0, and is well supported on the Arduino IDE using Teensyduino.

Teensy 3.1 adds several new features, due to an upgraded microcontroller. Here are the highlights. A table of technical specifications is show below.

More Memory For Awesome Projects

The RAM has quadrupled, from 16K to 64K. While 16K is plenty for nearly all Arduino libraries, 64K allows for more advanced applications. Icons and graphics for color displays and audio effects requiring delays, like reverb and chorus, will become possible on Teensy 3.1.

Flash memory has also doubled, to 256K, and provides double the memory bandwidth.

5 Volt Tolerance on Digital Inputs

Today most new chips use 3.3V signals, but many legacy products output 5 volt digital signals. These can now be directly connected to Teensy 3.1's digital inputs.

All digital pins are 5 volt tolerant on Teensy 3.1. However, the analog-only pins (A10-A14), AREF, Program and Reset are 3.3V only.

Update: Color Change Jan 22, 2014

The color of Teensy 3.1 was changed from black to green on January 22, 2014.

Before Jan 22
After Jan 22

The green material has slightly higher resolution. See this post for details.

12 Bit Analog Output

Teensy 3.1 has a proper analog output. You can always filter PWM, but true analog output responds rapidly. The output is created by the stable reference voltage, so it's doesn't vary if your power supply voltage changes slightly.

// Simple DAC sine wave test on Teensy 3.1

float phase = 0.0;
float twopi = 3.14159 * 2;
elapsedMicros usec = 0;

void setup() {
  analogWriteResolution(12);
}

void loop() {
  float val = sin(phase) * 2000.0 + 2050.0;
  analogWrite(A14, (int)val);
  phase = phase + 0.02;
  if (phase >= twopi) phase = 0;
  while (usec < 500) ; // wait
  usec = usec - 500;
}

Simply use analogWrite() on the A14 pin for true analog output.

Two Analog to Digital Converters

With analogRead(), you can measure many signals, but only 1 at a time. Teensy 3.1 has a second ADC, so you can concurrently measure 2 analog signals. For stereo audio or power monitoring, sampling both left and right, or voltage and current at the same moment is very beneficial.

Pedvide's ADC library can be used to access both ADCs.

PJRC is developing an advanced analog read function for Arduino, to make using these new analog input capabilities very easy.

CAN Bus

Controller Area Network is a communication used in automobiles. A new library to support Teensy 3.1's CAN controller is planned.

CAN bus development and sample code are being disussed on the forum.

Technical Specifications

FeatureTeensy 3.0Teensy 3.1Units
Price 19.00 19.80 US Dollars
Processor
    Core
    Rated Speed
    Overclockable
MK20DX128VLH5
Cortex-M4
48
96
MK20DX256VLH7
Cortex-M4
72
96


MHz
MHz
Flash Memory
    Bandwidth
    Cache
128
96
32
256
192
256
kbytes
Mbytes/sec
Bytes
RAM 16 64 kbytes
EEPROM 2 2 kbytes
Direct Memory Access 4 16 Channels
Digital I/O
    Voltage Output
    Voltage Input
34
3.3V
3.3V Only
34
3.3V
5V Tolerant
Pins
Volts
Volts
Analog Input
    Converters
        Resolution
            Usable
        Prog Gain Amp
    Touch Sensing
    Comparators
14
1
16
13
0
12
2
21
2
16
13
2
12
3
Pins

Bits
Bits

Pins

Analog Output
    DAC Resolution
0
-
1
12
Pins
Bits
Timers
    FTM Type
        PWM Outputs
    PDB Type
    CMT (infrared) Type
    LPTMR Type
    PIT (interval) Type
    Systick
    RTC (date/time) **
11 Total
2
10
1
1
1
4
1
1
12 Total
3
12
1
1
1
4
1
1


Pins
Communication
    USB
    Serial
        With FIFOs
        High Res Baud
        Fast Clock
    SPI
        With FIFOs
    I2C
    CAN Bus
    I2S Audio
        FIFO Size

1
3
1
3
2
1
1
1
0
1
4

1
3
2
3
2
1
1
2
1
1
8
** RTC requires a 32.768 kHz crystal & 3V battery. See the Time Library for details.

Pinouts

Teensy 3.1 is meant to be a drop-in replacement for Teensy 3.0. Only 1 pin has different functionality. The reset pin was replaced by A14/DAC, which you can use for true analog output, or as another analog input.

Teensy 3.0Teensy 3.1

Pins 3 and 4 gained CAN bus functions.

Pins 6, 9, 15, and 20-21 can still have SPI chip select capability, but the labels were removed to simplify the pinout card. Currently no libraries use the native chip selects. However, a new SPIFIFO library is in development.

Teensy 3.0Teensy 3.1

On the back side, 2 pins gained new PWM functionality and 6 pins have new analog input capability. A second I2C port is also added.

Reset Signal

Teensy 3.0 supported both a Program signal, to reboot into bootloader mode, and a traditional Reset signal, for a conventional reboot that restarts your application.

The Reset signal can be found on a new test point on the bottom side of Teensy 3.1.