What does DMA Request synchronization do? In the case of SPI_Rx does it trigger SPI reception when TIM12 updates (overflow) if i set synchronization signal to be TIM12 TRGO
Yes. The Reference Manual, which is your best source for understanding how the chip works, goes over it in some detail. The DMA request is held until a sync event happens, in this case TIM12_TRGO, which is the timer update if TRGO is set to the update event.
