Adafruit Trinket M0¶
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.
- 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
The adafruit_trinket_m0 board configuration supports the following hardware features:
|NVIC||on-chip||nested vector interrupt controller|
|Flash||on-chip||Can be used with NFFS to store files|
|SPI||on-chip||Serial Peripheral Interface ports|
Other hardware features are not currently supported by Zephyr.
The default configuration can be found in the Kconfig file boards/arm/adafruit_trinket_m0/adafruit_trinket_m0_defconfig.
Connections and IOs¶
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.
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).
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).
Programming and Debugging¶
The Trinket M0 ships the BOSSA compatible UF2 bootloader. The bootloader can be entered by quickly tapping the reset button twice.
Build the Zephyr kernel and the Hello World sample application:
west build -b adafruit_trinket_m0 samples/hello_world
Connect the Trinket M0 to your host computer using USB
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.
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
Tap the reset button twice quickly to enter bootloader mode
Flash the image:
west build -b adafruit_trinket_m0 samples/hello_world west flash
You should see “Hello World! arm” in your terminal.