1.. zephyr:board:: adafruit_trinket_m0
2
3Overview
4********
5
6The Adafruit Trinket M0 is a tiny (27 mm x 15 mm) ARM development
7board with an onboard RGB LED, USB port, and range of I/O broken out
8onto 5 pins.
9
10Hardware
11********
12
13- ATSAMD21E18A ARM Cortex-M0+ processor at 48 MHz
14- 256 KiB flash memory and 32 KiB of RAM
15- Internal trimmed 8 MHz oscillator
16- A user LED
17- An RGB DotStar LED
18- Native USB port
19- One reset button
20
21Supported Features
22==================
23
24The adafruit_trinket_m0 board configuration supports the following hardware
25features:
26
27+-----------+------------+------------------------------------------+
28| Interface | Controller | Driver/Component                         |
29+===========+============+==========================================+
30| NVIC      | on-chip    | nested vector interrupt controller       |
31+-----------+------------+------------------------------------------+
32| Flash     | on-chip    | Can be used with LittleFS to store files |
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| USB       | on-chip    | USB device                               |
47+-----------+------------+------------------------------------------+
48
49Other hardware features are not currently supported by Zephyr.
50
51The default configuration can be found in the Kconfig file
52:zephyr_file:`boards/adafruit/trinket_m0/adafruit_trinket_m0_defconfig`.
53
54Connections and IOs
55===================
56
57The `Adafruit Trinket M0 Learn site`_ has detailed information about
58the board including `pinouts`_ and the `schematic`_.
59
60System Clock
61============
62
63The SAMD21 MCU is configured to use the 8 MHz internal oscillator
64with the on-chip PLL generating the 48 MHz system clock.  The internal
65APB and GCLK unit are set up in the same way as the upstream Arduino
66libraries.
67
68Serial Port
69===========
70
71The SAMD21 MCU has 6 SERCOM based USARTs.  On the Trinket, SERCOM0 is
72the Zephyr console and is available on pins 3 (RX) and 4 (TX).
73SERCOM2 is available on pins 2 (RX) and 0 (TX).
74
75PWM
76===
77
78The SAMD21 MCU has 3 TCC based PWM units with up to 4 outputs each and a period
79of 24 bits or 16 bits.  If :code:`CONFIG_PWM_SAM0_TCC` is enabled then LED0 is
80driven by TCC0 instead of by GPIO.
81
82SPI Port
83========
84
85The SAMD21 MCU has 6 SERCOM based SPIs.  On the Trinket, SERCOM1 is
86used to drive the DotStar RGB LED.  SERCOM0 can be put into SPI mode
87and used to connect to devices over pin 2 (MISO), pin 4 (MOSI), and
88pin 3 (SCK).
89
90USB Device Port
91===============
92
93The SAMD21 MCU has a USB device port that can be used to communicate
94with a host PC.  See the :zephyr:code-sample-category:`usb` sample applications for
95more, such as the :zephyr:code-sample:`usb-cdc-acm` sample which sets up a virtual
96serial port that echos characters back to the host PC.
97
98Programming and Debugging
99*************************
100
101The Trinket M0 ships the BOSSA compatible UF2 bootloader.  The
102bootloader can be entered by quickly tapping the reset button twice.
103
104Additionally, if :code:`CONFIG_USB_CDC_ACM` is enabled then the bootloader
105will be entered automatically when you run :code:`west flash`.
106
107Flashing
108========
109
110#. Build the Zephyr kernel and the :zephyr:code-sample:`hello_world` sample application:
111
112   .. zephyr-app-commands::
113      :zephyr-app: samples/hello_world
114      :board: adafruit_trinket_m0
115      :goals: build
116      :compact:
117
118#. Connect the Trinket M0 to your host computer using USB
119
120#. Connect a 3.3 V USB to serial adapter to the board and to the
121   host.  See the `Serial Port`_ section above for the board's pin
122   connections.
123
124#. Run your favorite terminal program to listen for output. Under Linux the
125   terminal should be :code:`/dev/ttyACM0`. For example:
126
127   .. code-block:: console
128
129      $ minicom -D /dev/ttyACM0 -o
130
131   The -o option tells minicom not to send the modem initialization
132   string. Connection should be configured as follows:
133
134   - Speed: 115200
135   - Data: 8 bits
136   - Parity: None
137   - Stop bits: 1
138
139#. Tap the reset button twice quickly to enter bootloader mode
140
141#. Flash the image:
142
143   .. zephyr-app-commands::
144      :zephyr-app: samples/hello_world
145      :board: adafruit_trinket_m0
146      :goals: flash
147      :compact:
148
149   You should see "Hello World! adafruit_trinket_m0" in your terminal.
150
151References
152**********
153
154.. target-notes::
155
156.. _Adafruit Trinket M0 Learn site:
157    https://learn.adafruit.com/adafruit-trinket-m0-circuitpython-arduino
158
159.. _pinouts:
160    https://learn.adafruit.com/assets/49778
161
162.. _schematic:
163    https://learn.adafruit.com/assets/45723
164