boards/atmel/sam0/samr21_xpro/doc/index.rst
.. zephyr:board:: samr21_xpro
Overview
The SAM R21 Xplained Pro is a compact evaluation board by Atmel featuring a SAMR21G18A SoC. The SoC includes a SAMR21 ARM Cortex-M0+ micro-controller bundled with Atmel's AT86RF233, a 2.4GHz IEEE802.15.4 compatible radio. The kit includes Atmel’s Embedded Debugger (EDBG), which provides a full debug interface without the need for additional hardware.
Hardware
.. zephyr:board-supported-hw::
The SAM R21 Xplained Pro evaluation kit has 3 GPIO controllers. These controllers are responsible for pin muxing, input/output, pull-up, etc.
For more details please refer to SAM R21 Family Datasheet_ and the SAM R21 Xplained Pro Schematic_.
.. image:: img/ATSAMR21-XPRO-pinout.jpg :align: center :alt: SAMR21-XPRO-pinout
The SAMR21 MCU is configured to use the 32.768 kHz external oscillator with the on-chip PLL generating the 48 MHz system clock.
The SAMR21 MCU has six SERCOM based USARTs with two configured as USARTs in this BSP. SERCOM0 is the default Zephyr console.
The SAMR21 MCU has 3 TCC based PWM units with up to 4 outputs each and a
period of 24 bits or 16 bits. If :code:CONFIG_PWM_SAM0_TCC is enabled then
LED0 is driven by TCC0 instead of by GPIO.
The SAMR21 MCU has 6 SERCOM based SPIs.
When connecting an I2C device and a logic analyzer to an I2C port at the same time, the internal pull-up resistors are not sufficient for stable bus operation. You probably have to connect external pull-ups to both bus lines. 10K is a good value to start with.
The SAMR21 SoC includes an on-chip AT86RF233 radio. It is internally connected via SPI and some GPIO pins and behaves the same way as externally connected SPI devices.
+-------------+------------------------------------------------------------------------------------------+
| Sensor | AT86RF233 |
+=============+==========================================================================================+
| Type | 2.4GHz IEEE802.15.4 radio |
+-------------+------------------------------------------------------------------------------------------+
| Vendor | Atmel |
+-------------+------------------------------------------------------------------------------------------+
| Datasheet |Datasheet <http://www.atmel.com/images/atmel-8351-mcu_wireless-at86rf233_datasheet.pdf>_|
+-------------+------------------------------------------------------------------------------------------+
| connected to| SPI_0 |
+-------------+------------------------------------------------------------------------------------------+
| Pin Config: |
+-------------+------------------------------------------------------------------------------------------+
| Device | SERCOM4 |
+-------------+------------------------------------------------------------------------------------------+
| MOSI | PB30 (OUT, SPI MOSI) |
+-------------+------------------------------------------------------------------------------------------+
| MISO | PC19 (IN, SPI MISO) |
+-------------+------------------------------------------------------------------------------------------+
| SCLK | PC18 (OUT, SPI SCLK) |
+-------------+------------------------------------------------------------------------------------------+
| CS | PB31 (OUT, GPIO output) |
+-------------+------------------------------------------------------------------------------------------+
| IRQ | PB00 (IN, GPIO external interrupt) |
+-------------+------------------------------------------------------------------------------------------+
| RSTN | PB15 (OUT, GPIO output) |
+-------------+------------------------------------------------------------------------------------------+
| SLP_TR | PA20 (OUT, GPIO output) |
+-------------+------------------------------------------------------------------------------------------+
Zephyr provide several samples that can use this technology. You can check
:zephyr:code-sample:wpan-serial example as starting points.
Another good test can be done with IPv6 by using the server/client
echo demo. More information at :zephyr:code-sample:sockets-echo-server and
:zephyr:code-sample:sockets-echo-client.
Programming and Debugging
.. zephyr:board-supported-runners::
The SAM R21 Xplained Pro comes with a Atmel Embedded Debugger (EDBG). This provides a debug interface to the SAMR21 chip and is supported by OpenOCD.
#. Build the Zephyr kernel and the :zephyr:code-sample:hello_world sample application:
.. zephyr-app-commands:: :zephyr-app: samples/hello_world :board: samr21_xpro :goals: build :compact:
#. Connect the SAM R21 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 :code:/dev/ttyACM0. For example:
.. code-block:: console
$ minicom -D /dev/ttyACM0 -o
The -o option tells minicom not to send the modem initialization string. Connection should be configured as follows:
#. To flash an image:
.. zephyr-app-commands:: :zephyr-app: samples/hello_world :board: samr21_xpro :goals: flash :compact:
You should see "Hello World! samr21_xpro" in your terminal.
References
.. target-notes::
.. _Microchip website: http://www.microchip.com/DevelopmentTools/ProductDetails.aspx?PartNO=ATSAMR21-XPRO
.. _SAM R21 Family Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/sam-r21_datasheet.pdf
.. _SAM R21 Xplained Pro Schematic: http://ww1.microchip.com/downloads/en/DeviceDoc/SAMR21-Xplained-Pro_Design-Documentation.zip