Hello VKarl.2,
If you want to replace the onboard MCU with a different one you have to apply HW & FW changes to your setup.
HW changes
For the HW changes pleases have a look to schematic for details https://www.st.com/resource/en/schematic_pack/st25ru3993-hpev_v1_schematics.pdf
- Remove zero ohm resistors: R7 – R13 to disconnect onboard MCU from SPI & control line.
- External SPI connections to new MCU: EN -> J12.3, IRQ -> J12.4, NCS -> J12.5, CLK -> J10.1, MOSI -> J10.2, MISO -> J10.3
- Disable the Onboard MCU: Remove R61, short C25 (solder bridge)
- To control usage of internal and external PA the onboard RF switch must be control external from the new MCU. Remove R90 & R91 and connect new PA switch control lines to J30
- To deactivate the external PA and reduce power consumption in the idle state remove R43 and control the external PA supply enable line via J4.
- To control the RF Switch for Antenna Output remove R92 & R93 connect new switch control lines to J31
- To control the Control Carrier Cancellation Circuit (CCC) external remove R38-R40 and connect the the three SPI enable lines of the tunable capacitors via J13
FW changes
For STM32 MCU's open the ST25RU3993_Eval.ioc project file from the STUHFL SDK package "./Firmware/Eval" and check all connections to the peripherals and adopt them to reflect your HW changes.
To run the FW on a NUCLEO-L476RG board means you use the same STM32L4RGTx MCU. Therefore, no need to change any settings of used MCU itself, the core or peripheral settings is needed.
After generating the new NUCLEO-L476RG project for STM32CubeIDE or KEIL you have a empty project.
In the Eval FW project sources of the STUHFL SDK package you find in the "./Firmware/Src" and "./Firmware/Inc" folders all sources that are platform independent. Include them into your project.
Also include the path to the "./Middleware/clib/STUHFL/inc" and "./Middleware/clib/STUHFL/inc/platform" to your project include path.
In this folder all defines & prototypes located that shared between the FW and the host application.
As you stay on the STM32L4 last step is to compare, check and merge all modification inside the STM32CubeIDE generated files from the user code sections.
These are the platform dependent files and can be found in "./Firmware/Eval/Src" and "./Firmware/Eval/Inc"
NOTE: By default the FW uses 3MBaud for UART host communication. The build in UART-USB converter of the ST-Link on the STM32L4 Nucleo support only 115KBaud
Please use on the Nucleo board one of the UARTs accessible via the pin header and connect there a UART-USB converter cable. When changing the UART please do not forget to update in the STM32CubeIDE configuration and FW to reflect the new UART setting.
BR
Nick
