zephyr

Introduction

These directories provide the implementation of the porting layer on the Zephyr platform. Instructions on how to install the necessary tools and perform the build can be found in the runner directory. Though this is intended to become a generic Zephyr platform, at the moment it supports only Nordic MCUs as they require a specific version/configuration of Zephyr.

Note: the directory structure here differs from that in the other platform directories in order to follow more closely the approach adopter by Zephyr, which is hopefully familiar to Zephyr users.

• app: contains the code that runs the test application (both examples and unit tests) on the Zephyr platform.
• cfg: contains the configuration files for the MCU, the OS, for the application and for testing (mostly which MCU pins are connected to which module pins).
• src: contains the implementation of the porting layers for Zephyr platform.
• runner: contains the test application configuration and build files for the MCUs supported on the Zephyr platform.
• boards: contains custom u-blox boards that are not [yet] in the Zephyr repo.

SDK Installation

ubxlib is tested with nRFConnect SDK version 1.6.1 which is the recommended version.

Follow the instructions to install the development tools:

• Install nRF connect. https://www.nordicsemi.com/Software-and-Tools/Development-Tools/nRF-Connect-for-desktop
• Start nRFConnect and use the tool chain manager to install the recommended SDK version (see above).
• IMPORTANT!: Update SDK and toolchain using the dropdown menu for your SDK version.

Integration

ubxlib is a Zephyr module. To add ubxlib to your Zephyr application you can make use of ZEPHYR_EXTRA_MODULES. By adding the following line to the top of your existing CMakeLists.txt, Zephyr should pickup ubxlib:

list(APPEND ZEPHYR_EXTRA_MODULES <PATH_TO_UBXLIB_DIRECTORY>)

You must then also enable UBXLIB either via menuconfig or by adding the following line to your prj.conf:

CONFIG_UBXLIB=y

ubxlib also requires some Zephyr config to be enabled, but you currently need to check runner/prj.conf to get these correct.

SDK Usage

Segger Embedded Studio

When you install nRFConnect SDK for Windows you will get a copy of Segger Embedded Studio (SES). You can either start SES from the nRF Toolchain Manager by clicking "Open Segger Embedded Studio" or by running toolchain/SEGGER Embedded Studio.cmd found in your installation of nRFconnect SDK.

• Always load project from SES using file->Open nRF connect SDK project
• Select the project folder containing the CMakeLists.txt of the application you want to build.
• Board file should be {your_sdk_path}/zephyr/boards/arm/nrf5340dk_nrf5340 for EVK-NORA-B1. For a custom board e.g. port/platform/zephyr/boards/short_range/zephyr/boards/arm/ubx_evkninab4_nrf52833
• Board name should be nrf5340dk_nrf5340_cpuapp for EVK-NORA-B1. For a custom board e.g. ubx_evkninab4_nrf52833.
• Where a board-specific configuration file is available (e.g. ubx_evkninab4_nrf52833.conf) this will be picked up automatically.

Device Tree

Zephyr pin choices for any HW peripheral managed by Zephyr (e.g. UART, I2C, SPI, etc.) are made at compile-time in the Zephyr device tree, they cannot be passed into the ubxlib functions as run-time variables. Look in the zephyr/zephyr.dts file located in your build directory to find the resulting pin allocations for these peripherals. If you want to find out more about device tree please see Zephyr Introduction to devicetree

Important UART Note

Since pin assignment for UARTs are made in the device tree, functions such as uPortUartOpen() which take pin assignments as parameters, should have all the pins set to -1. You can look through the resulting zephyr/zephyr.dts located in your build directory to find the UART you want to use. The UARTs will be named uart0, uart1, ... in the device tree - the ending number is the value you should use to tell ubxlib what UART to open.

Additional Notes

• Zephyr is assumed to use its internal minimal C library, not newlib; this is because the Zephyr integration of newlib is not threadsafe. If, at some point in the future, the integration is made thread-safe, or if you make it thread-safe yourself, and you wish to use newlib then you should configure Zephyr appropriately and then add U_CFG_ZEPHYR_USE_NEWLIB to the conditional compilation flags passed into the build (see below for how to do this without modifying CMakeLists.txt).

• Always clean the build directory when upgrading to a new ubxlib version.

• You may override or provide conditional compilation flags to CMake without modifying CMakeLists.txt. Do this by setting an environment variable U_FLAGS, e.g.:

  set U_FLAGS=-DMY_FLAG
  

  ...or:

  set U_FLAGS=-DMY_FLAG -DU_CFG_APP_PIN_CELL_ENABLE_POWER=-1