STMicroelectronics STM32WLEx Reference Manual page 358

Peripherals interconnect matrix
10.3.14 From timer (LPTIM3) to sub-GHz radio SPI NSS
Purpose
Low-power timer LPTIM3 can be used to generate a sub-GHz radio SPI NSS event.
Triggering signals
The output from low-power timer is on signal LPTIM3_OUT event.
The connection between timers and sub-GHz radio SPI NSS is provided in
SPI control register
Active power modes
Run, Sleep, LPRun, LPSleep
358/1306
(PWR_SUBGHZSPICR).
RM0461 Rev 5
RM0461
PWR sub-GHz