Trinket M0

Overview

The Adafruit Trinket M0 is a tiny (27 mm x 15 mm) ARM development board with an onboard RGB LED, USB port, and range of I/O broken out onto 5 pins.

Hardware

  • ATSAMD21E18A ARM Cortex-M0+ processor at 48 MHz

  • 256 KiB flash memory and 32 KiB of RAM

  • Internal trimmed 8 MHz oscillator

  • A user LED

  • An RGB DotStar LED

  • Native USB port

  • One reset button

Supported Features

The adafruit_trinket_m0 board supports the hardware features listed below.

on-chip / on-board
Feature integrated in the SoC / present on the board.
2 / 2
Number of instances that are enabled / disabled.
Click on the label to see the first instance of this feature in the board/SoC DTS files.
vnd,foo
Compatible string for the Devicetree binding matching the feature.
Click on the link to view the binding documentation.

Connections and IOs

The Adafruit Trinket M0 Learn site [1] has detailed information about the board including pinouts [2] and the schematic [3].

System Clock

The SAMD21 MCU is configured to use the 8 MHz internal 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. On the Trinket, SERCOM0 is the Zephyr console and is available on pins 3 (RX) and 4 (TX). SERCOM2 is available on pins 2 (RX) and 0 (TX).

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. If CONFIG_PWM_SAM0_TCC is enabled then LED0 is driven by TCC0 instead of by GPIO.

SPI Port

The SAMD21 MCU has 6 SERCOM based SPIs. On the Trinket, SERCOM1 is used to drive the DotStar RGB LED. SERCOM0 can be put into SPI mode and used to connect to devices over pin 2 (MISO), pin 4 (MOSI), and pin 3 (SCK).

USB Device Port

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

Programming and Debugging

The adafruit_trinket_m0 board supports the runners and associated west commands listed below.

flash debug

The Trinket M0 ships the BOSSA compatible UF2 bootloader. The bootloader can be entered by quickly tapping the reset button twice.

Additionally, if CONFIG_USB_CDC_ACM is enabled then the bootloader will be entered automatically when you run west flash.

Flashing

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

    west build -b adafruit_trinket_m0 samples/hello_world

  2. Connect the Trinket M0 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 adafruit_trinket_m0 samples/hello_world
west flash

    You should see “Hello World! adafruit_trinket_m0” in your terminal.

References