Adafruit Feather M0 LoRa

Overview

The Adafruit Feather M0 Lora is a thin, light ARM development boards with an onboard battery connector and charger for 3.7 V lithium polymer batteries, charging status indicator and user LEDs, native USB connector, 20 I/O pins, and a LoRa radio module from Semtech.

Adafruit Feather M0 LoRa

Hardware

  • ATSAMD21G18A ARM Cortex-M0+ processor at 48 MHz

  • 32.768 kHz crystal oscillator

  • 256 KiB flash memory and 32 KiB of RAM

  • Battery connector and charger for 3.7 V lithium polymer batteries

  • Charging indicator LED

  • User LED

  • Reset button

  • Native USB port

  • SX127x LoRa radio

Supported Features

The adafruit_feather_m0_lora board configuration supports the following hardware features:

Interface

Controller

Driver/Component

NVIC

on-chip

Nested vector interrupt controller

Flash

on-chip

Can be used with LittleFS to store files

SYSTICK

on-chip

Systick

WDT

on-chip

Watchdog

GPIO

on-chip

I/O ports

USART

on-chip

Serial port

I2C

on-chip

Inter-Integrated Circuit

SPI

on-chip

Serial Peripheral Interface port

USB

on-chip

USB device

RADIO

SPI

LoRa radio

Other hardware features are not currently supported by Zephyr.

The default configuration can be found in the Kconfig file boards/adafruit/feather_m0_lora/adafruit_feather_m0_lora_defconfig.

Connections and IOs

The Adafruit Feather M0 with LoRa radio module 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 32.768 kHz external oscillator with the on-chip PLL generating the 48 MHz system clock.

Serial Port

The SAMD21 MCU has 6 SERCOM based USARTs. On the Adafruit Feather M0 with LoRa, SERCOM0 is the Zephyr console and is available on pins 0 (RX) and 1 (TX).

I2C Port

The SAMD21 MCU has 6 SERCOM based USARTs. On the Adafruit Feather M0 with LoRa, SERCOM3 is available on pin 20 (SDA) and pin 21 (SCL).

SPI Port

The SAMD21 MCU has 6 SERCOM based SPIs. On the Adafruit Feather M0 with LoRa, SERCOM4 is available on pin 22 (MISO), pin 23 (MOSI), and pin 24 (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 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.

LoRa Radio

The Semtech SX127x radio chip on the Adafruit Feather M0 with LoRa is attached to the SPI port (SERCOM4). Depending on the hardware version, 433MHz or 900MHz is supported.

Programming and Debugging

The Adafruit Feather M0 with LoRa ships with a BOSSA compatible SAM-BA 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_feather_m0_lora samples/hello_world

  2. Connect the Adafruit Feather M0 with LoRa 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_feather_m0_lora samples/hello_world
west flash

    You should see “Hello World! adafruit_feather_m0_lora” in your terminal.

References