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boards: atsamr21_xpro: Add SAM R21 Xplained Pro Evaluation Kit

Add the Atmel SAM R21 Xplained Pro Evaluation Kit to zephyr.

So far, UART, SPI, I2C (depends on #14128), debug LED and user button
have been tested.

Signed-off-by: Benjamin Valentin <benpicco@googlemail.com>
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benpicco authored and nashif committed Feb 19, 2019
1 parent 770233d commit 360fe70ee713f06fa8d03fff8fa5a08f535ba996
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# Copyright (c) 2019 Benjamin Valentin
# SPDX-License-Identifier: Apache-2.0
if(CONFIG_PINMUX_SAM0)
zephyr_library()
zephyr_library_sources(pinmux.c)
endif()
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# Kconfig - SAM R21 Xplained Pro Board configuration
#
# Copyright (c) 2019 Benjamin Valentin
# SPDX-License-Identifier: Apache-2.0

config BOARD_ATSAMR21_XPRO
bool "SAM R21 Xplained Pro"
depends on SOC_PART_NUMBER_SAMR21G18A
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# Kconfig - SAM R21 Xplained Pro board configuration
#
# Copyright (c) 2019 Benjamin Valentin
# SPDX-License-Identifier: Apache-2.0

if BOARD_ATSAMR21_XPRO

config BOARD
default "atsamr21_xpro"

endif # BOARD_ATSAMR21_XPRO
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/*
* Copyright (c) 2019 Benjamin Valentin
*
* SPDX-License-Identifier: Apache-2.0
*/

/dts-v1/;
#include <atmel/samr21.dtsi>

/ {
model = "SAM R21 Xplained Pro";
compatible = "atsamr21,xpro", "atmel,samr21g18a", "atmel,samr21";

chosen {
zephyr,console = &sercom0;
zephyr,shell-uart = &sercom0;
zephyr,sram = &sram0;
zephyr,flash = &flash0;
};

/* These aliases are provided for compatibility with samples */
aliases {
led0 = &led0;
sw0 = &user_button;
};

leds {
compatible = "gpio-leds";
led0: led_0 {
gpios = <&porta 19 0>;
label = "Yellow LED";
};
};

buttons {
compatible = "gpio-keys";
user_button: button_0 {
gpios = <&porta 28 (GPIO_PUD_PULL_UP | GPIO_INT_ACTIVE_LOW)>;
label = "SW0";
};
};
};

&sercom0 {
status = "ok";
compatible = "atmel,sam0-uart";
current-speed = <115200>;
rxpo = <1>;
txpo = <0>;
};

&sercom5 {
status = "ok";
compatible = "atmel,sam0-spi";
dipo = <0>;
dopo = <2>;
label = "SPI_0";
};

&usb0 {
status = "ok";
};
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# Copyright (c) 2019 Benjamin Valentin
# SPDX-License-Identifier: Apache-2.0
identifier: atsamr21_xpro
name: SAM R21 Xplained Pro
type: mcu
arch: arm
ram: 32
flash: 256
toolchain:
- zephyr
- gnuarmemb
- xtools
supported:
- gpio
- spi
- usb_device
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# Copyright (c) 2019 Benjamin Valentin
# SPDX-License-Identifier: Apache-2.0
CONFIG_ARM=y
CONFIG_SOC_FAMILY_SAM0=y
CONFIG_SOC_SERIES_SAMR21=y
CONFIG_SOC_PART_NUMBER_SAMR21G18A=y
CONFIG_BOARD_ATSAMR21_XPRO=y
CONFIG_CORTEX_M_SYSTICK=y
CONFIG_CONSOLE=y
CONFIG_UART_CONSOLE=y
CONFIG_SERIAL=y
CONFIG_UART_SAM0=y
CONFIG_UART_INTERRUPT_DRIVEN=y
CONFIG_GPIO=y
CONFIG_GPIO_SAM0=y
CONFIG_WATCHDOG=y
CONFIG_WDT_SAM0=y
CONFIG_SOC_ATMEL_SAMD_XOSC32K=y
CONFIG_SOC_ATMEL_SAMD_XOSC32K_AS_MAIN=y
CONFIG_PINMUX=y
CONFIG_PINMUX_SAM0=y
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# Copyright (c) 2019 Benjamin Valentin
# SPDX-License-Identifier: Apache-2.0

include(${ZEPHYR_BASE}/boards/common/openocd.board.cmake)
Binary file not shown.
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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 |
+-----------+------------+--------------------------------------+

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
- 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.


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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