SAM D21 Xplained Pro Evaluation Kit¶
The SAM D21 Xplained Pro evaluation kit is ideal for evaluation and prototyping with the SAM D21 Cortex®-M0+ processor-based microcontrollers. The kit includes Atmel’s Embedded Debugger (EDBG), which provides a full debug interface without the need for additional hardware.
- ATSAMD21J18 ARM Cortex-M0+ processor at 48 MHz
- 32.768 kHz crystal oscillator
- 256 KiB flash memory and 32 KiB of RAM
- One yellow user LED
- One mechanical user push button
- One reset button
- On-board USB based EDBG unit with serial console
The atsamd21_xpro 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
The SAM D21 Xplained Pro evaluation kit has 3 GPIO controllers. These controllers are responsible for pin muxing, input/output, pull-up, etc.
Default Zephyr Peripheral Mapping:¶
- SERCOM0 USART TX : PA10
- SERCOM0 USART RX : PA11
- SERCOM1 USART TX : PA16
- SERCOM1 USART RX : PA19
- SERCOM3 USART TX : PA22
- SERCOM3 USART RX : PA23
- SERCOM5 SPI MISO : PB16
- SERCOM5 SPI MOSI : PB22
- SERCOM5 SPI SCK : PB23
- GPIO SPI CS : PB17
- GPIO LED0 : PB30
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 SAMD21 MCU has six SERCOM based USARTs with three configured as USARTs in this BSP. SERCOM3 is the default Zephyr console.
- SERCOM0 9600 8n1
- SERCOM1 115200 8n1
- SERCOM3 115200 8n1 connected to the onboard Atmel Embedded Debugger (EDBG)
The SAMD21 MCU has 6 SERCOM based SPIs. On the SAM D21 Xplained Pro, SERCOM5 is connected to an 8 megabit SPI flash.
Programming and Debugging¶
The SAM D21 Xplained Pro comes with a Atmel Embedded Debugger (EDBG). This provides a debug interface to the SAMD21 chip and is supported by OpenOCD.
Build the Zephyr kernel and the
west build -b atsamd21_xpro samples/hello_world
Using CMake and ninja:
cmake -B build -GNinja -DBOARD=atsamd21_xpro samples/hello_world ninja -C build
Connect the SAM D21 Xplained Pro to your host computer using the USB debug port.
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
To flash an image:
Using CMake and ninja:
cmake -B build -GNinja -DBOARD=atsamd21_xpro samples/hello_world ninja -C build flash
You should see “Hello World! arm” in your terminal.