These directories provide the configuration and build metadata for the NRF52 MCU under the nRF5 SDK. The configuration here is sufficient to run the ubxlib tests and examples, no attempt is made to optimise the MCU RAM/flash etc. sizes, you need to know how to do that yourself.
- cfg: contains the configuration files for the MCU, for the application and for testing (mostly which MCU pins are connected to which module pins).
- gcc: contains the installation instructions and build files for the nRF5 SDK with GCC/Make as the toolchain.
In order to preserve valuable HW resources this code is configured to send trace output over the SWDIO (AKA RTT) port which a Segger J-Link debugger can interpret.
If you are using an NRF52840 DK board such a debugger is already included on the board. If you're working to a bare NF52 chip or a bare u-blox NINA-B3 module you should equip yourself with a Segger J-Link Base debugger and the right cable to connect it to your board.
For debugging you will need the Segger J-Link tools, of which the Windows ones can be found here:
https://www.segger.com/downloads/jlink/JLink_Windows.exe
If you don't have an NRF52 board with Segger J-Link built in or you have a bare module etc. and are without a Segger J-Link box, you can modify the sdk_config.h file in the cfg directory to send trace out of a spare UART instead. You would need to enable a UART port, switch off NRF_LOG_BACKEND_RTT_ENABLED and modify the NRF_LOG_BACKEND_UART_ENABLED, NRF_LOG_BACKEND_UART_TX_PIN and NRF_LOG_BACKEND_UART_BAUDRATE variables.
This code requires the use of a TIMER peripheral as a timer tick source.
If you connect a u-blox module via one of the UARTs an additional TIMER peripheral will be required per UART to count received characters via a PPI (Programmable Peripheral Interconnect) channel.
The default TIMER choices are specified in cellular_cfg_hw_platform_specific.h and can be overriden at compile time.