Arduino MKR Zero

Overview

The Arduino MKR Zero built with smaller MKR form factor and powered by Atmel’s SAMD21 MCU. This board come with microSD card holder that allows you to play with music files with no extra hardware.

Arduino MKR Zero

Hardware

  • ATSAMD21G18A ARM Cortex-M0+ processor at 48 MHz

  • 32.768 kHz crystal oscillator

  • 256 KiB flash memory and 32 KiB of RAM

  • One user LEDs

  • One reset button

  • microSD card slot

  • ATECC508A secure element

Supported Features

The arduino_mkrzero board configuration supports the following hardware features:

Interface

Controller

Driver/Component

ADC

on-chip

Analog to digital converter

COUNTER

on-chip

Pulse counter

DMA

on-chip

Direct memory access unit

Flash

on-chip

Can be used with LittleFS to store files

GPIO

on-chip

I/O ports

HWINFO

on-chip

Hardware info and serial number

NVIC

on-chip

nested vector interrupt controller

PWM

on-chip

Pulse Width Modulation

SPI

on-chip

Serial Peripheral Interface ports

I2C

on-chip

Inter-Integrated Circuit ports

SYSTICK

on-chip

systick

USART

on-chip

Serial ports

USB

on-chip

USB device

WDT

on-chip

Watchdog

Other hardware features are not currently supported by Zephyr.

The default configuration can be found in the Kconfig boards/arduino/mkrzero/arduino_mkrzero_defconfig.

Connections and IOs

The Arduino store [1] has detailed information about board connections. Download the Arduino MKR Zero Schematic [2] for more detail.

System Clock

The SAMD21 MCU is configured to use the 32.768 kHz external oscillator with the on-chip PLL generating the 48 MHz system clock. The internal APB and GCLK unit are set up in the same way as the upstream Arduino libraries.

Serial Port

The SAMD21 MCU has 6 SERCOM based USARTs. SERCOM5 is available on pins 13(PA23) and 14(PA22).

PWM

The SAMD21 MCU has 3 TCC based PWM units with up to 4 outputs each and a period of 24 bits or 16 bits.

SPI Port

The SAMD21 MCU has 6 SERCOM based SPIs. On the Arduino MKR Zero, SERCOM1 is available on pin 8, 9, and 10. SERCOM2 connect to microSD card slot as SPI interface.

I2C Port

The SAMD21 MCU has 6 SERCOM based I2Cs. SERCOM0 is available on pin 11(PA08) and 12(PA09). This I2C bus also available as ESLOV(JST SH 5pin) socket. ATECC508A secure element is connect to this I2C bus.

USB Device Port

The SAMD21 MCU has a USB device port that can be used to communicate with a host PC. See the USB device support samples sample applications for more, such as the USB CDC-ACM sample which sets up a virtual serial port that echos characters back to the host PC.

DAC

The SAMD21 MCU has a single channel DAC with 10 bits of resolution. On the Arduino MKR Zero, the DAC is available on pin A0.

Programming and Debugging

The Arduino MKR Zero ships the BOSSA compatible bootloader. The bootloader can be entered by quickly tapping the reset button twice.

Flashing

  1. Build the Zephyr kernel and the Hello World sample application:

    west build -b arduino_mkrzero samples/hello_world

  2. Connect the MKR Zero to your host computer using USB

  3. Connect a 3.3 V USB to serial adapter to the board and to the host. See the Serial Port section above for the board’s pin connections.

  4. Run your favorite terminal program to listen for output. Under Linux the terminal should be /dev/ttyACM0. For example:

    $ minicom -D /dev/ttyACM0 -o

    The -o option tells minicom not to send the modem initialization string. Connection should be configured as follows:

    • Speed: 115200

    • Data: 8 bits

    • Parity: None

    • Stop bits: 1

  5. Tap the reset button twice quickly to enter bootloader mode

  6. Flash the image:

    west build -b arduino_mkrzero samples/hello_world
west flash

    You should see “Hello World! arduino_mkrzero” in your terminal.

References