How do stm32wl33 and sub-1GHz wireless (Radio) communicate?

[KiteLee]

SPI or serial port?

If it weren't for those two, Then why must the MCU_API_delay() function be set while ((LL_USART_IsActiveFlag_TXE_TXFNF(USART1) == RESET) || (LL_USART_IsActiveFlag_TC(USART1)) == RESET)) {};

We can use both uart of MCU, so I want to confirm with you whether it is necessary to configure here.

[Andrew Neil]

See the datasheet - they communicate via the Bus Matrix:

https://www.st.com/resource/en/datasheet/stm32wl33k8.pdf#page=6

via https://www.st.com/en/microcontrollers-microprocessors/stm32wl33k8.html#documentation

[KiteLee]

thk's,

That's the MRSUBG in STM32CubeMX.

uart non-SIGFOX must be configured.