1.. zephyr:board:: samr21_xpro
2
3Overview
4********
5
6The SAM R21 Xplained Pro is a compact evaluation board by Atmel featuring a
7SAMR21G18A SoC. The SoC includes a SAMR21 ARM Cortex-M0+ micro-controller
8bundled with Atmel's AT86RF233, a 2.4GHz IEEE802.15.4 compatible radio.
9The kit includes Atmel’s Embedded Debugger (EDBG), which provides a full
10debug interface without the need for additional hardware.
11
12Hardware
13********
14
15- SAMR21G18A ARM Cortex-M0+ processor at 48 MHz
16- 32.768 kHz crystal oscillator
17- 256 KiB flash memory and 32 KiB of RAM
18- One yellow user LED
19- One mechanical user push button
20- One reset button
21- On-board USB based EDBG unit with serial console
22
23Supported Features
24==================
25
26The samr21_xpro board configuration supports the following hardware
27features:
28
29+-----------+------------+--------------------------------------+
30| Interface | Controller | Driver/Component                     |
31+===========+============+======================================+
32| NVIC      | on-chip    | nested vector interrupt controller   |
33+-----------+------------+--------------------------------------+
34| SYSTICK   | on-chip    | systick                              |
35+-----------+------------+--------------------------------------+
36| WDT       | on-chip    | Watchdog                             |
37+-----------+------------+--------------------------------------+
38| GPIO      | on-chip    | I/O ports                            |
39+-----------+------------+--------------------------------------+
40| PWM       | on-chip    | Pulse Width Modulation               |
41+-----------+------------+--------------------------------------+
42| USART     | on-chip    | Serial ports                         |
43+-----------+------------+--------------------------------------+
44| SPI       | on-chip    | Serial Peripheral Interface ports    |
45+-----------+------------+--------------------------------------+
46| I2C       | on-chip    | I2C Peripheral Interface ports       |
47+-----------+------------+--------------------------------------+
48
49Other hardware features are not currently supported by Zephyr.
50
51The default configuration can be found in the Kconfig
52:zephyr_file:`boards/atmel/sam0/samr21_xpro/samr21_xpro_defconfig`.
53
54Pin Mapping
55===========
56
57The SAM R21 Xplained Pro evaluation kit has 3 GPIO controllers. These
58controllers are responsible for pin muxing, input/output, pull-up, etc.
59
60For more details please refer to `SAM R21 Family Datasheet`_ and the `SAM R21
61Xplained Pro Schematic`_.
62
63.. image:: img/ATSAMR21-XPRO-pinout.jpg
64     :align: center
65     :alt: SAMR21-XPRO-pinout
66
67Default Zephyr Peripheral Mapping:
68----------------------------------
69- SERCOM0 USART TX : PA5
70- SERCOM0 USART RX : PA4
71- SERCOM1 I2C SDA  : PA16
72- SERCOM1 I2C SCL  : PA17
73- SERCOM5 SPI MISO : PB02
74- SERCOM5 SPI MOSI : PB22
75- SERCOM5 SPI SCK  : PB23
76- GPIO SPI CS      : PB03
77- GPIO/PWM LED0    : PA19
78
79System Clock
80============
81
82The SAMR21 MCU is configured to use the 32.768 kHz external oscillator
83with the on-chip PLL generating the 48 MHz system clock.
84
85Serial Port
86===========
87
88The SAMR21 MCU has six SERCOM based USARTs with two configured as USARTs in
89this BSP. SERCOM0 is the default Zephyr console.
90
91- SERCOM0 115200 8n1 connected to the onboard Atmel Embedded Debugger (EDBG)
92
93PWM
94===
95
96The SAMR21 MCU has 3 TCC based PWM units with up to 4 outputs each and a
97period of 24 bits or 16 bits.  If :code:`CONFIG_PWM_SAM0_TCC` is enabled then
98LED0 is driven by TCC0 instead of by GPIO.
99
100SPI Port
101========
102
103The SAMR21 MCU has 6 SERCOM based SPIs.
104
105- SERCOM5 is exposed via Xplained Pro Standard Extension Header
106
107I2C Port
108========
109
110When connecting an I2C device and a logic analyzer to an I2C port at the same
111time, the internal pull-up resistors are not sufficient for stable bus
112operation. You probably have to connect external pull-ups to both bus lines. 10K
113is a good value to start with.
114
115- SERCOM1 is exposed via Xplained Pro Standard Extension Header
116
117Radio
118=====
119
120The SAMR21 SoC includes an on-chip AT86RF233 radio. It is internally
121connected via SPI and some GPIO pins and behaves the same way as
122externally connected SPI devices.
123
124+-------------+------------------------------------------------------------------------------------------+
125| Sensor      | AT86RF233                                                                                |
126+=============+==========================================================================================+
127| Type        | 2.4GHz IEEE802.15.4 radio                                                                |
128+-------------+------------------------------------------------------------------------------------------+
129| Vendor      | Atmel                                                                                    |
130+-------------+------------------------------------------------------------------------------------------+
131| Datasheet   |`Datasheet <http://www.atmel.com/images/atmel-8351-mcu_wireless-at86rf233_datasheet.pdf>`_|
132+-------------+------------------------------------------------------------------------------------------+
133| connected to| SPI_0                                                                                    |
134+-------------+------------------------------------------------------------------------------------------+
135| Pin Config:                                                                                            |
136+-------------+------------------------------------------------------------------------------------------+
137| Device      | SERCOM4                                                                                  |
138+-------------+------------------------------------------------------------------------------------------+
139| MOSI        | PB30 (OUT, SPI MOSI)                                                                     |
140+-------------+------------------------------------------------------------------------------------------+
141| MISO        | PC19 (IN, SPI MISO)                                                                      |
142+-------------+------------------------------------------------------------------------------------------+
143| SCLK        | PC18 (OUT, SPI SCLK)                                                                     |
144+-------------+------------------------------------------------------------------------------------------+
145| CS          | PB31 (OUT, GPIO output)                                                                  |
146+-------------+------------------------------------------------------------------------------------------+
147| IRQ         | PB00 (IN, GPIO external interrupt)                                                       |
148+-------------+------------------------------------------------------------------------------------------+
149| RSTN        | PB15 (OUT, GPIO output)                                                                  |
150+-------------+------------------------------------------------------------------------------------------+
151| SLP_TR      | PA20 (OUT, GPIO output)                                                                  |
152+-------------+------------------------------------------------------------------------------------------+
153
154Zephyr provide several samples that can use this technology. You can check
155:zephyr:code-sample:`wpan-serial` example as starting points.
156Another good test can be done with IPv6 by using the server/client
157echo demo. More information at :zephyr:code-sample:`sockets-echo-server` and
158:zephyr:code-sample:`sockets-echo-client`.
159
160Programming and Debugging
161*************************
162
163The SAM R21 Xplained Pro comes with a Atmel Embedded Debugger (EDBG).  This
164provides a debug interface to the SAMR21 chip and is supported by
165OpenOCD.
166
167Flashing
168========
169
170#. Build the Zephyr kernel and the :zephyr:code-sample:`hello_world` sample application:
171
172   .. zephyr-app-commands::
173      :zephyr-app: samples/hello_world
174      :board: samr21_xpro
175      :goals: build
176      :compact:
177
178#. Connect the SAM R21 Xplained Pro to your host computer using the USB debug
179   port.
180
181#. Run your favorite terminal program to listen for output. Under Linux the
182   terminal should be :code:`/dev/ttyACM0`. For example:
183
184   .. code-block:: console
185
186      $ minicom -D /dev/ttyACM0 -o
187
188   The -o option tells minicom not to send the modem initialization
189   string. Connection should be configured as follows:
190
191   - Speed: 115200
192   - Data: 8 bits
193   - Parity: None
194   - Stop bits: 1
195
196#. To flash an image:
197
198   .. zephyr-app-commands::
199      :zephyr-app: samples/hello_world
200      :board: samr21_xpro
201      :goals: flash
202      :compact:
203
204   You should see "Hello World! samr21_xpro" in your terminal.
205
206References
207**********
208
209.. target-notes::
210
211.. _Microchip website:
212    http://www.microchip.com/DevelopmentTools/ProductDetails.aspx?PartNO=ATSAMR21-XPRO
213
214.. _SAM R21 Family Datasheet:
215    http://ww1.microchip.com/downloads/en/devicedoc/sam-r21_datasheet.pdf
216
217.. _SAM R21 Xplained Pro Schematic:
218    http://ww1.microchip.com/downloads/en/DeviceDoc/SAMR21-Xplained-Pro_Design-Documentation.zip
219