| .. _adafruit_itsybitsy_m4_express: |
| |
| Adafruit ItsyBitsy M4 Express |
| ############################# |
| |
| Overview |
| ******** |
| |
| The Adafruit ItsyBitsy M4 express is a small (36 mm x 18 mm) ARM development |
| board with an onboard RGB LED, USB port, 2 MiB of SPI flash, and range of I/O |
| broken out onto 23 GPIO pins. |
| |
| .. image:: img/adafruit_itsybitsy_m4_express.jpg |
| :align: center |
| :alt: Adafruit ItsyBitsy M4 Express |
| |
| Hardware |
| ******** |
| |
| - ATSAMD51G19A ARM Cortex-M4 processor at 120 MHz |
| - 512 KiB of flash memory and 192 KiB of RAM |
| - 2 MiB of SPI flash |
| - Internal trimmed 8 MHz oscillator |
| - A user LED |
| - An RGB DotStar LED |
| - Native USB port |
| - One reset button |
| |
| Supported Features |
| ================== |
| |
| The adafruit_itsybitsy_m4_express 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 | |
| +-----------+------------+------------------------------------------+ |
| | TRNG | on-chip | True Random Number Generator | |
| +-----------+------------+------------------------------------------+ |
| | HWINFO | on-chip | Unique 128 bit serial number | |
| +-----------+------------+------------------------------------------+ |
| | RTC | on-chip | Real-Time Counter | |
| +-----------+------------+------------------------------------------+ |
| | USB | on-chip | USB device | |
| +-----------+------------+------------------------------------------+ |
| | WDT | on-chip | Watchdog Timer | |
| +-----------+------------+------------------------------------------+ |
| | PWM | on-chip | PWM | |
| +-----------+------------+------------------------------------------+ |
| |
| Other hardware features are not currently supported by Zephyr. |
| |
| The default configuration can be found in the Kconfig file |
| :zephyr_file:`boards/adafruit/itsybitsy_m4_express/adafruit_itsybitsy_m4_express_defconfig`. |
| |
| Zephyr can use the default Cortex-M SYSTICK timer or the SAM0 specific RTC. |
| To use the RTC, set :code:`CONFIG_CORTEX_M_SYSTICK=n` and set |
| :code:`CONFIG_SYS_CLOCK_TICKS_PER_SEC` to no more than 32 kHZ divided by 7, |
| i.e. no more than 4500. |
| |
| Connections and IOs |
| =================== |
| |
| The `Adafruit Learning System`_ has detailed information about |
| the board including `pinouts`_ and the `schematic`_. |
| |
| System Clock |
| ============ |
| |
| The SAMD51 MCU is configured to use the 32 kHz internal oscillator |
| with the on-chip PLL generating the 120 MHz system clock. |
| |
| Serial Port |
| =========== |
| |
| The SAMD51 MCU has 6 SERCOM based USARTs. On the ItsyBitsy, SERCOM3 is |
| the Zephyr console and is available on pins 0 (RX) and 1 (TX). |
| |
| SPI Port |
| ======== |
| |
| The SAMD51 MCU has 6 SERCOM based SPIs. On the ItsyBitsy, SERCOM1 can be put |
| into SPI mode and used to connect to devices over the SCK (SCLK), MO (MOSI), and |
| MI (MISO) pins. |
| |
| PWM |
| === |
| |
| The SAMD51 has three PWM generators with up to six channels each. :code:`TCC_0` |
| has a resolution of 24 bits and all other generators are 16 bit. :code:`TCC_1` |
| pin 2 is mapped to PA18 (D7) and pin 3 is mapped to PA19 (D9). |
| |
| USB Device Port |
| =============== |
| |
| The SAMD51 MCU has a USB device port that can be used to communicate |
| with a host PC. See the :ref:`usb-samples` sample applications for |
| more, such as the :zephyr:code-sample:`usb-cdc-acm` sample which sets up a virtual |
| serial port that echos characters back to the host PC. |
| |
| Programming and Debugging |
| ************************* |
| |
| The ItsyBitsy ships with a the BOSSA compatible UF2 bootloader. The |
| bootloader can be entered by quickly tapping the reset button twice. |
| |
| Additionally, if :code:`CONFIG_USB_CDC_ACM` is enabled then the bootloader |
| will be entered automatically when you run :code:`west flash`. |
| |
| Flashing |
| ======== |
| |
| #. Build the Zephyr kernel and the :ref:`hello_world` sample application: |
| |
| .. zephyr-app-commands:: |
| :zephyr-app: samples/hello_world |
| :board: adafruit_itsybitsy_m4_express |
| :goals: build |
| :compact: |
| |
| #. Connect the ItsyBitsy to your host computer using USB |
| |
| #. Connect a 3.3 V USB to serial adapter to the board and to the |
| host. See the `Serial Port`_ section above for the board's pin |
| connections. |
| |
| #. Run your favorite terminal program to listen for output. Under Linux the |
| terminal should be :code:`/dev/ttyUSB0`. For example: |
| |
| .. code-block:: console |
| |
| $ minicom -D /dev/ttyUSB0 -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 |
| |
| #. Tap the reset button twice quickly to enter bootloader mode |
| |
| #. Flash the image: |
| |
| .. zephyr-app-commands:: |
| :zephyr-app: samples/hello_world |
| :board: adafruit_itsybitsy_m4_express |
| :goals: flash |
| :compact: |
| |
| You should see "Hello World! adafruit_itsybitsy_m4_express" in your terminal. |
| |
| Debugging |
| ========= |
| |
| In addition to the built-in bootloader, the ItsyBitsy can be flashed and |
| debugged using a SWD probe such as the Segger J-Link. |
| |
| #. Connect the board to the probe by connecting the :code:`SWCLK`, |
| :code:`SWDIO`, :code:`RESET`, :code:`GND`, and :code:`3V3` pins on the |
| ItsyBitsy to the :code:`SWCLK`, :code:`SWDIO`, :code:`RESET`, :code:`GND`, |
| and :code:`VTref` pins on the `J-Link`_. |
| |
| #. Flash the image: |
| |
| .. zephyr-app-commands:: |
| :zephyr-app: samples/hello_world |
| :board: adafruit_itsybitsy_m4_express |
| :goals: flash |
| :flash-args: -r openocd |
| :compact: |
| |
| #. Start debugging: |
| |
| .. zephyr-app-commands:: |
| :zephyr-app: samples/hello_world |
| :board: adafruit_itsybitsy_m4_express |
| :goals: debug |
| :compact: |
| |
| References |
| ********** |
| |
| .. target-notes:: |
| |
| .. _Adafruit Learning System: |
| https://learn.adafruit.com/introducing-adafruit-itsybitsy-m4 |
| |
| .. _pinouts: |
| https://learn.adafruit.com/introducing-adafruit-itsybitsy-m4/pinouts |
| |
| .. _schematic: |
| https://learn.adafruit.com/introducing-adafruit-itsybitsy-m4/downloads |
| |
| .. _J-Link: |
| https://www.segger.com/products/debug-probes/j-link/technology/interface-description/ |