Welcome to MattairTech!

Your Shopping cart is empty.

Skip to Main Content »

MT-D21E Microchip / Atmel SAMD21 / L21 / C21 ARM Cortex M0+ USB development board

Availability: In stock

  • Buy 5 for $19.99 each and save 14%
Accepting MC, VISA, AMEX, Discover, PayPal

Quick Overview

Revision B now available!

Arduino support is now available here
Arduino compatible SAM-BA USB-CDC bootloader will be preinstalled on all chips (C21E supports TTL Serial only).

Documentation is now available here
Headers included.

Configuration Options
Choose SAMD, SAML, or SAMC:
(usually only 256KB version, see docs for more MCU info)
D21E General purpose SAM M0+ MCU, USB, I2S
Also used in the Arduino Zero
L21E   Low power features, enhanced analog peripherals,
USB, crypto/TRNG, custom logic
      - Inductor installed to support on-chip buck converter
C21E 5V support on board, MPU, 2x CAN instead
of USB, Sigma-Delta and 2x SAR ADCs
      - Can connect Vcc (default 3.3V) to 5V from USB Vbus.
      - DO NOT use FLASH with 5V.

Choose Optional Memory Device:
(will connect to MCU using SPI at up to 12MHz)
*   128KB SRAM with battery backup
            - Can connect Vbat header pin (coin cell) to SRAM backup pin
*    512KB FLASH with protection features and OTP page
*    64KB EEPROM with OTP page

All come with SAM-BA bootloader preinstalled:
*   USB CDC Serial supported with D21 and L21
*   TTL Serial supported with all three chips

Revision B includes the following changes:

*    Add support for more MCU options (SAMD, SAML, or SAMC)
      - With SAML, an inductor is installed to support the buck converter
      - USB Vbus can be connected to Vcc to support SAMC at 5V
*    Serial memory device can be installed
      (128K SRAM, 512KB FLASH, or 64KB EEPROM)
      - Using SPI at up to 12MHz using pins A18, A19, A22 (A27 for CS)
*    Added Vbat and Gnd pins (coin cell), can connect to SRAM,
      and/or Vcc (advanced)
*    Button A now jumper A to make room for memory device,
      used as CS for memory as well
*    Moved the blue LED to pin A6 (arduino pin 6),
      changed resistor to 1Kohm (600uA @ 3.3V)
*    Physically larger PTC fuse (0805) with
      higher trip (500mA) and hold (250mA)
*    Changed ESD device to protect Vbus in addition to D+ and D-

MT-D21E Rev B

Double click on above image to view full picture

Zoom Out
Zoom In

More Views

  • MT-D21E Rev B
  • MT-D21E Rev B pinout
  • MT-D21E Rev B bottom
  • MT-D21E Rev B schematic

* Required Fields




The MT-D21E is a development board for the 32-pin Microchip / Atmel SAMx21E ARM Cortex M0+ microcontrollers. Choose between the D21E (general purpose M0+ MCU, USB, I2S, also used in the Arduino Zero), L21E (low power features, enhanced analog, USB, crypto/TRNG, custom logic), or C21E (5V support, MPU, 2x CAN instead of USB, Sigma-Delta and 2x SAR ADCs). An optional SPI serial memory device can be mounted (128KB SRAM w/backup, 512KB FLASH, or 64KB EEPROM). The board can be powered from USB or the Vin pin, with 2 schottky diodes providing simple switching and reverse-polarity protection. This voltage is regulated to 3.3V by the onboard 250mA, extremely low quiescent current (2uA) LDO regulator which supports up to 16V on Vin. The C21 supports 5V operation by connecting USB Vbus to Vcc (jumpers). A 250mA (hold) PTC resettable fuse provides overcurrent protection. Also mounted is a mini USB connector with ESD protection, blue LED, 16MHz crystal, 32.768KHz crystal, button, jumper, and Vbat input. Arduino 1.6.x compatible core files (1.6.x, 1.8.x IDE) for all 3 chips are provided. A SAM-BA USB CDC bootloader (TTL serial only for C21) is preinstalled for programming without an external tool (Arduino or standalone use). The Cortex header (10-pin, 50-mil) can be used with an external debugger/programmer. There are 40 dual inline header pins with 0.1” pin spacing and 0.7” row spacing which allows for breadboard or perfboard mounting. The PCB measures 2.1” x 0.9” x 0.062” (52mm x 23mm x 1.6mm) with two 3mm mounting holes.


*    Microchip / Atmel ARM Cortex M0+ 32-pin microcontroller
            Choice of SAMD, SAML, or SAMC chips
                  D21E (general purpose SAM M0+ MCU, USB, I2S, also used in the Arduino Zero)
                  L21E (low power features, enhanced analog, USB, crypto/TRNG, custom logic)
                  C21E (5V support, MPU, 2x CAN instead of USB, Sigma-Delta and 2x SAR ADCs)
            CPU operates at up to 48MHz
            All chips available with up to 256KB FLASH and 32KB of SRAM
            All chips feature 6 timers, RTC, 4 SERCOM, DMA, PTC, AC
*   Optional SPI Serial Memory Device
           128KB SRAM with battery backup (Vbat pin)
           512KB FLASH with protection features and OTP page
           64KB EEPROM with OTP page
*   Onboard 3.3V, 250mA LDO regulator
           Supports up to 16V DC input on Vin pin
           Extremely low quiescent current (2.0uA typical)
           Over-current and over-temperature protection
*   Powered by USB Vbus or external power source on Vin (up to 16V)
           Simple diode power source switching,reverse-polarity protection
           With the C21E installed, USB Vbus can be connected to Vcc for 5V operation
*   Arduino 1.6.x compatible core (1.6.x, 1.8.x IDE)
*   SAM-BA USB CDC bootloader (D21 and L21 only, C21 has serial bootloader)
           Arduino compatible (use the Arduino IDE to upload)
           Bossa command line utility (Windows, Linux, limited OS X)
*   PTC resettable fuse (250mA hold / 500mA trip)
*   Cortex Debug Header (10-pin, 50-mil) for device programming and debugging
*   16MHz crystal (use PLL for up to 48MHz cpu clock)
*   32.768KHz crystal (use PLL or FLL for up to 48MHz cpu clock)
*   Blue Status LED (can be disconnected)
*   Jumper A for general use (pin A27)
*   Button B configurable for reset or general use (pin A31) with debouncing
*   Two 4.7Kohm resistors can be connected to pins A16 and A17 for use with I2C
*   Mini USB connector with ESD protection on USB Vbus, D+, and D- lines
*   USB pins (or CAN on the C21) routed to header pins (for panel-mount connector)
*   Ferrite bead and 2 capacitors on analog supply
*   Two capacitors each can be enabled for pins A3 and/or A4 for use with external references
*   24 solder jumpers on PCB bottom for configuration flexibility
*   All PORT pins can be routed to headers
*   2 main headers are on 0.1” spacing (breadboard/perfboard mounting), 0.7” apart
*   Two 3mm mounting holes (~5mm pad)
*   High-quality PCB with gold-plated finish
*   Measures approx. 2.1” x 0.9” (52mm x 23mm) and 0.062” (1.6mm) thick


    User Guide

Schematic for Rev B

CNC Drill File for Rev B


Arduino Support


Arduino support (1.6.x, 1.8.x IDE) is now available.

Drivers for Arduino and SAM-BA Bootloader


Signed drivers for the SAM-BA CDC bootloader and for Arduino (CDC, HID, MIDI, MSD).
See https://www.mattairtech.com/support/ for installation instructions.

SAM-BA Bootloader


These are the SAM-BA bootloaders that comes pre-installed.

SAM-BA Bootloader Utility

        These are the SAM-BA bootloader utilities for transferring firmware.

bossac-1.7.0-mattairtech-1-mingw32-64.zip (Windows 32 bit and 64 bit)
Bossa-1.7.0-mattairtech-1-x86_64-linux-gnu.tar.gz (Linux 64 bit, includes Bossa GUI and Bossa shell)
bossac-1.7.0-mattairtech-1-i686-linux-gnu.tar.gz (Linux 32 bit)
bossac-1.7.0-mattairtech-1-x86_64-apple-darwin.tar.gz (OS X 10.5+, 64 bit) 

Test Firmware (Arduino blink sketch)


The Rev B blink sketch will be posted here soon.
The link is for the Rev A Arduino blink sketch with USB (CDC + HID). This comes optionally pre-installed.
See https://www.mattairtech.com/support/ for details.

MSD Bootloader Source and Binaries (Rev A only)


Blink Demo (MSD Bootloader or No Bootloader options) (Rev A only)


MT-D21E_Blink.zip contains the blink demo hex file that comes pre-installed (Rev A only).
It simply blinks the LED at 1Hz using an internal clock source.


This development board/kit is intended for use for FURTHER ENGINEERING, DEVELOPMENT, DEMONSTRATION, OR EVALUATION PURPOSES ONLY. It is not a finished product, and may not (yet) comply with some or any technical or legal requirements that are applicable to finished products, including, without limitation, directives regarding electromagnetic compatibility, recycling (WEEE), FCC, CE, or UL (except as may be otherwise noted on the board/kit). MattairTech LLC supplied this board/kit AS IS, without any warranties, with all faults, at the buyer's and further users' sole risk. The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user indemnifies Atmel from all claims arising from the handling or use of the goods. Due to the open construction of the product, it is the user's responsibility to take any and all appropriate precautions with regard to electrostatic discharge and any other technical or legal concerns.

The authors disclaim all warranties with regard to this software, including all implied warranties of merchantability and fitness. In no event shall any author be liable for any special, indirect or consequential damages or any damages whatsoever resulting from loss of use, data or profits, whether in an action of contract, negligence or other tortious action, arising out of or in connection with the use or performance of this software.

Accepting MC, VISA, AMEX, Discover, PayPal