We expand our Anjay integration using Zephyr OS on nRF9160 Development Kit – the board popular among IoT devices and desired by our clients. It offers two push buttons and switches, four LEDs and a GPS module with both onboard and external antennas. Apart from that, there is also a nanoSIM card slot to let users connect to the LTE network.
First of all, integrating anjay on the next board made us restructure the project directory tree. Separating and moving
CMakeLists.txt files to
projects/* subdirectories were essential to make the app compatible with two different boards. The
CMakeLists.txt file in the root directory is included in
CMakeLists.txt files mentioned before and configures the build process depending on the build target (
During development, we made use of nRF Connect SDK provided by Nordic Semiconductor. It contains Zephyr RTOS and libraries recommended for various devices, including nRF9160.
One of the problems we faced was the entropy driver.
CC310 library has the
entropy_get_entropy function, which requires an input buffer to be 144 bytes long – it dictates more complex implementation of the
entropy_callback function used in the
Another challenge was clock synchronization. Using the
lte_lc library forced us to add new configuration entries (e.g.
CONFIG_BSD_LIBRARY=y). After that modification, the
CONFIG_POSIX_API=y entry generated an error so it had to be removed. Because of that,
clock_settime used in
set_system_time on the STM platform couldn't be reutilized on the nRF9160 platform. This issue led us to the
date_time library. The source of the current timestamp is the external NTP server defined in
default_config.h. This timestamp is then obtained in the
avs_time_real_now function present in
date_time_now. The library updates timestamp periodically by means of internal methods – the update interval is set with the
The GitHub repository has been updated with described integration. Developers can track changes listed in the