practic_les7_ada_spi2_tx_dma

-- WeAct BlackPill STM32F411CEU6 -- HSI= 16MHz -- SPI2 - Send packet data -- DMA1 Stream4 Channel 0 - RM0383 page 170 -- * GPIOB Pin13 -> SCK -- * GPIOB Pin14 -> MISO -- * GPIOB Pin15 -> MOSI -- *