TRRS Trinkey

Overview

The Adafruit TRRS Trinkey is a small ARM development board with an onboard TRRS jack, RGB LED, USB port, and STEMMA QT port.

Hardware

  • ATSAMD21E18A ARM Cortex-M0+ processor at 48 MHz

  • 256 KiB flash memory and 32 KiB of RAM

  • Internal trimmed 8 MHz oscillator

  • TRRS jack

  • STEMMA QT I2C Port

  • An RGB NeoPixel LED

  • Native USB port

  • One reset button

Supported Features

The adafruit_trrs_trinkey 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 TRRS Trinkey 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.

TRRS Jack

The TRRS jack is connected to the following pins of the SAMD21 MCU:

Pin

Function

PA02 (AIN0)

Tip

PA03 (AIN1)

Tip Switch

PA04 (AIN4)

Ring 2

PA05 (AIN5)

Sleeve

PA06 (AIN6)

Ring 1

PA07 (AIN7)

Ring Switch

USB Serial Port

Since the TRRS Trinkey has a native USB port, and lacks dedicated UART pins, the USB CDC ACM serial port is used for console I/O.

STEMMA QT I2C Port

The SAMD21E MCU has 5 SERCOM-based I2C peripherals. On the TRRS Trinkey, SERCOM2 is used to drive the STEMMA QT I2C port.

RGB NeoPixel LED

The board has one NeoPixel WS2812B RGB LED connected to pin PA01. Unfortunately no Zephyr driver currently exists for this configuration of MCU and pin.

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. Since the TRRS Trinkey doesn’t have UART pins, the USB CDC ACM serial is enabled by default for console I/O.

Programming and Debugging

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

flash debug

The TRRS Trinkey ships the BOSSA compatible UF2 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 adafruit_trrs_trinkey samples/hello_world

  2. Connect the TRRS Trinkey to your host computer using USB

  3. 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

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

  5. Flash the image:

    west build -b adafruit_trrs_trinkey samples/hello_world
west flash

    You should see “Hello World! adafruit_trrs_trinkey/samd21e18a” in your terminal.

References