The Zephyr Project is a scalable real-time operating system (RTOS) supporting multiple hardware architectures, optimized for resource constrained devices, and built with security in mind.

The Zephyr OS is based on a small-footprint kernel designed for use on resource-constrained systems: from simple embedded environmental sensors and LED wearables to sophisticated smart watches and IoT wireless gateways.

The Zephyr kernel supports multiple architectures, including ARM Cortex-M, Intel x86, ARC, Nios II, Tensilica Xtensa, and RISC-V, and a large number of supported boards.

Notes on Adafruit Feather nRF52840 Sense

The information below introduces how to use the Adafruit's default bootloader to download a Zephyr image to the board. This is convenient as it does not require an external J-Link programmer and the Adafruit Feather nRF52840 Sense board does not have a built-in socket to connect the J-Link programmer.

You need to follow the Adafruit's instruction to setup the Arduino environment first: https://learn.adafruit.com/adafruit-feather-sense adafruit-nrfutil will be installed as part of this procedure.

Then follow the Getting Started Guide of Zephyr (https://docs.zephyrproject.org/latest/) and replace ~/zephyrproject/zephyr with this repository.

Compile and run Blinky

• Compile:

  west build -b adafruit_feather_nrf52840_sense samples/basic/blinky

• Download:

  Enter the DFU mode by double-clicking the Reset button of the Sense board. When ready, a large Green LED will turn on and the Sense device will be detected as a USB Mass storage (FTHRSNSBOOT) on your host machine. Then,

  adafruit-nrfutil dfu genpkg --dev-type 0x0052 --sd-req 0x00B6 --application build/zephyr/zephyr.hex build/zephyr/zephyr.zip

  adafruit-nrfutil --verbose dfu serial -pkg build/zephyr/zephyr.zip -p /dev/ttyACM0 -b 115200 --singlebank

  /dev/ttyACM0 is the serial port for the Sense board.

  If this fails, try updating the bootloader: https://learn.adafruit.com/bluefruit-nrf52-feather-learning-guide/updating-the-bootloader

• Change kernel configuration (similar to Linux kernel menuconfig; don't use if not needed):

  west build -t menuconfig

Other programs

You may need to delete the build folder before compiling another application.

• Button

  Turns on the RED led while the User SW button is being pressed. No printk output is visible from this program.

  west build -b adafruit_feather_nrf52840_sense samples/basic/blinky

  adafruit-nrfutil dfu genpkg --dev-type 0x0052 --sd-req 0x00B6 --application build/zephyr/zephyr.hex build/zephyr/zephyr.zip

  adafruit-nrfutil --verbose dfu serial -pkg build/zephyr/zephyr.zip -p /dev/ttyACM0 -b 115200 --singlebank

• USB Console

  west build -b adafruit_feather_nrf52840_sense samples/subsys/usb/console/

  adafruit-nrfutil dfu genpkg --dev-type 0x0052 --sd-req 0x00B6 --application build/zephyr/zephyr.hex build/zephyr/zephyr.zip

  adafruit-nrfutil --verbose dfu serial -pkg build/zephyr/zephyr.zip -p /dev/ttyACM0 -b 115200 --singlebank

  This program enables USB-Serial, so you can check printk output on your host computer. Use the Arduino IDE's serial monitor or sudo minicom in a terminal.

  Refer to the source code (samples/subsys/usb/console/src/main.c) and the project config (samples/subsys/usb/console/prj.conf) of this sample to enable printk in your program.

• BLE Beacon

  west build -b adafruit_feather_nrf52840_sense samples/bluetooth/beacon/

  adafruit-nrfutil dfu genpkg --dev-type 0x0052 --sd-req 0x00B6 --application build/zephyr/zephyr.hex build/zephyr/zephyr.zip

  adafruit-nrfutil --verbose dfu serial -pkg build/zephyr/zephyr.zip -p /dev/ttyACM0 -b 115200 --singlebank

  See the Adafruit's beacon for testing.

• BLE Beacon + LED + UART

  west build -b adafruit_feather_nrf52840_sense samples/bluetooth/beacon_led_uart/

  adafruit-nrfutil dfu genpkg --dev-type 0x0052 --sd-req 0x00B6 --application build/zephyr/zephyr.hex build/zephyr/zephyr.zip

  adafruit-nrfutil --verbose dfu serial -pkg build/zephyr/zephyr.zip -p /dev/ttyACM0 -b 115200 --singlebank

  A naive integration of the three sample programs. The program blinks and prints every second when the serial monitor is on; otherwise, the device goes to sleep mode and LED blinks very slowly.

Getting Started

Welcome to Zephyr! See the Introduction to Zephyr for a high-level overview, and the documentation's Getting Started Guide to start developing.

Community Support

Community support is provided via mailing lists and Slack; see the Resources below for details.

Resources

Here's a quick summary of resources to help you find your way around:

• Help: Asking for Help Tips
• Documentation: http://docs.zephyrproject.org (Getting Started Guide)
• Source Code: https://github.com/zephyrproject-rtos/zephyr is the main repository; https://elixir.bootlin.com/zephyr/latest/source contains a searchable index
• Releases: https://github.com/zephyrproject-rtos/zephyr/releases
• Samples and example code: see Sample and Demo Code Examples
• Mailing Lists: [email protected] and [email protected] are the main user and developer mailing lists, respectively. You can join the developer's list and search its archives at Zephyr Development mailing list. The other Zephyr mailing list subgroups have their own archives and sign-up pages.
• Nightly CI Build Status: https://lists.zephyrproject.org/g/builds The [email protected] mailing list archives the CI (buildkite) nightly build results.
• Chat: Zephyr's Slack workspace is https://zephyrproject.slack.com. Use this Slack Invite to register.
• Contributing: see the Contribution Guide
• Wiki: Zephyr GitHub wiki
• Issues: https://github.com/zephyrproject-rtos/zephyr/issues
• Security Issues: Email [email protected] to report security issues; also see our Security documentation. Security issues are tracked separately at https://zephyrprojectsec.atlassian.net.
• Zephyr Project Website: https://zephyrproject.org