.. zephyr:board:: adafruit_itsybitsy

Overview

The Adafruit ItsyBitsy nRF52840 Express is a small (36 mm x 18 mm) ARM development board with an onboard RGB LED, USB port, 2 MB of QSPI flash, and range of I/O broken out onto 21 GPIO pins.

This development kit has the following features:

:abbr:ADC (Analog to Digital Converter)
CLOCK
FLASH
:abbr:GPIO (General Purpose Input Output)
:abbr:I2C (Inter-Integrated Circuit)
:abbr:I2S (Inter-Integrated Sound)
:abbr:MPU (Memory Protection Unit)
:abbr:NVIC (Nested Vectored Interrupt Controller)
:abbr:PWM (Pulse Width Modulation)
:abbr:QSPI (Quad Serial Peripheral Interface)
RADIO (Bluetooth Low Energy and 802.15.4)
:abbr:RTC (nRF RTC System Clock)
:abbr:SPI (Serial Peripheral Interface)
:abbr:UARTE (Universal asynchronous receiver-transmitter)
:abbr:USB (Universal Serial Bus)
:abbr:WDT (Watchdog Timer)

Hardware

nRF52840 ARM Cortex-M4F CPU at 64MHz
1 MB of flash memory and 256 KB of SRAM
2 MB of QSPI flash
A user LED
A user switch
An RGB DotStar LED
Native USB port
One reset button

Supported Features

.. zephyr:board-supported-hw::

Connections and IOs

The Adafruit ItsyBitsy nRF52840 Express Learn site_ has detailed information about the board including pinouts_ and the schematic_.

LED

LED0 (red) = P0.06
LED1 (Adafruit DotStar)
- DATA = P0.08
- CLK = P1.09

Push buttons

SWITCH = P0.29
RESET = P0.18

Logging

Logging is done using the USB-CDC port. See the :zephyr:code-sample:logging sample or the :zephyr:code-sample:usb-cdc-acm-console sample applications to see how this works.

Testing LEDs and buttons on the Adafruit ItsyBitsy nRF52840 Express

The :zephyr:code-sample:button sample lets you test the buttons (switches) and the red LED. The :zephyr:code-sample:blinky sample lets you test the red LED.

The DotStar LED has been implemented as a SPI device and can be tested with the :zephyr:code-sample:led-strip sample application.

You can build and flash the examples to make sure Zephyr is running correctly on your board. The button and LED definitions can be found in :zephyr_file:boards/adafruit/itsybitsy/adafruit_itsybitsy_nrf52840.dts.

Programming and Debugging

.. zephyr:board-supported-runners::

The ItsyBitsy ships with the BOSSA compatible UF2 bootloader. The bootloader can be entered by quickly tapping the reset button twice.

First time setup

Some versions of this board were shipped with a buggy bootloader. Ensure that the bootloader is up to date by following the Adafruit UF2 Bootloader update_ tutorial. Note that this tutorial was made for the Adafruit Feather nRF52840, but the steps to update the bootloader are the same for the ItsyBitsy. The files for the ItsyBitsy bootloader can be found in the Adafruit nRF52 Bootloader repo_.

The building and flashing of Zephyr applications have been tested with release 0.7.0 of the UF2 bootloader.

Flashing

Flashing is done by dragging and dropping the built Zephyr UF2-file into the :code:ITSY840BOOT drive.

#. Build the Zephyr kernel and the :zephyr:code-sample:blinky sample application:

.. zephyr-app-commands:: :zephyr-app: samples/basic/blinky :board: adafruit_itsybitsy/nrf52840 :goals: build :compact:

#. Connect the ItsyBitsy to your host computer using USB

#. Tap the reset button twice quickly to enter bootloader mode

#. Flash the image:

Drag and drop the file :code:samples/basic/blinky/build/zephyr/zephyr.uf2 into :code:ITSY840BOOT

The device will disconnect and you should see the red LED blink.

References

.. target-notes::

.. _Adafruit ItsyBitsy nRF52840 Express Learn site: https://learn.adafruit.com/adafruit-itsybitsy-nrf52840-express

.. _pinouts: https://learn.adafruit.com/adafruit-itsybitsy-nrf52840-express/pinouts

.. _schematic: https://learn.adafruit.com/adafruit-itsybitsy-nrf52840-express/downloads

.. _Adafruit UF2 Bootloader update: https://learn.adafruit.com/introducing-the-adafruit-nrf52840-feather/update-bootloader

.. _Adafruit nRF52 Bootloader repo: https://github.com/adafruit/Adafruit_nRF52_Bootloader/releases