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.. _atsamr21_xpro:
SAM R21 Xplained Pro Evaluation Kit
###################################
Overview
********
The SAM R21 Xplained Pro is a compact evaluation board by Atmel featuring a
ATSAMR21G18A 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.
.. image:: img/atsamr21_xpro.png
:width: 500px
:align: center
:alt: ATSAMR21-XPRO
Hardware
********
- ATSAMR21G18A 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
Supported Features
==================
The atsamr21_xpro board configuration supports the following hardware
features:
+-----------+------------+--------------------------------------+
| Interface | Controller | Driver/Component |
+===========+============+======================================+
| NVIC | on-chip | nested vector interrupt controller |
+-----------+------------+--------------------------------------+
| SYSTICK | on-chip | systick |
+-----------+------------+--------------------------------------+
| WDT | on-chip | Watchdog |
+-----------+------------+--------------------------------------+
| GPIO | on-chip | I/O ports |
+-----------+------------+--------------------------------------+
| USART | on-chip | Serial ports |
+-----------+------------+--------------------------------------+
| SPI | on-chip | Serial Peripheral Interface ports |
+-----------+------------+--------------------------------------+
| I2C | on-chip | I2C Peripheral Interface ports |
+-----------+------------+--------------------------------------+
Other hardware features are not currently supported by Zephyr.
The default configuration can be found in the Kconfig
``boards/arm/atsamr21_xpro/atsamr21_xpro_defconfig``.
Pin Mapping
===========
The SAM R21 Xplained Pro evaluation kit has 3 GPIO controllers. These
controllers are responsible for pin muxing, input/output, pull-up, etc.
For mode details please refer to `SAM R21 Family Datasheet`_ and the `SAM R21
Xplained Pro Schematic`_.
.. image:: img/ATSAMR21-XPRO-pinout.png
:width: 500px
:align: center
:alt: ATSAMR21-XPRO-pinout
Default Zephyr Peripheral Mapping:
----------------------------------
- SERCOM0 USART TX : PA5
- SERCOM0 USART RX : PA4
- SERCOM1 I2C SDA : PA16
- SERCOM1 I2C SCL : PA17
- SERCOM5 SPI MISO : PB02
- SERCOM5 SPI MOSI : PB22
- SERCOM5 SPI SCK : PB23
- GPIO SPI CS : PB03
- GPIO LED0 : PB17
System Clock
============
The SAMR21 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 SAMR21 MCU has six SERCOM based USARTs with two configured as USARTs in
this BSP. SERCOM0 is the default Zephyr console.
- SERCOM0 115200 8n1 connected to the onboard Atmel Embedded Debugger (EDBG)
SPI Port
========
The SAMR21 MCU has 6 SERCOM based SPIs.
- SERCOM5 is exposed via Xplained Pro Standard Extension Header
I2C Port
========
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.
- SERCOM1 is exposed via Xplained Pro Standard Extension Header
Radio
=====
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) |
+-------------+------------------------------------------------------------------------------------------+
Programming and Debugging
*************************
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.
Flashing
========
#. Build the Zephyr kernel and the :ref:`hello_world` sample application:
.. zephyr-app-commands::
:zephyr-app: samples/hello_world
:board: atsamr21_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:
- Speed: 115200
- Data: 8 bits
- Parity: None
- Stop bits: 1
#. To flash an image:
.. zephyr-app-commands::
:zephyr-app: samples/hello_world
:board: atsamr21_xpro
:goals: flash
:compact:
You should see "Hello World! arm" 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
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