On the motherboard, the SPI device is configured as a full master duplex with DMA and NSS hardware modes. The TIM2 is configured to generate a 4KHz PWM signal with a 50% key ratio on TIM2_CH2 pin (PA.01), this signal is used as a DMA trigger and as an NSS signal input to lock SPI data transmissions. While in slave-board, spi-device is configured as Slave Full Duplex with DMA and NSS hardware modes. In both adapters, the SPI is configured to use slave hardware management to manage the NSS pin. This example provides a small application that uses controller buttons to trigger SPI communication with DMA and using the SPI firmware library. . . .