CONFIG_SPI_NRFX_RAM_BUFFER_SIZE=8 CONFIG_SPI_3=y CONFIG_SPI_3_NRF_SPIM=y CONFIG_SPI_3_NRF_RX_DELAY=1 CONFIG_SPI_LOOPBACK_DRV_NAME="SPI_3" CONFIG_SPI_LOOPBACK_CS_GPIO=y CONFIG_SPI_LOOPBACK_CS_CTRL_GPIO_DRV_NAME="GPIO_0" CONFIG_SPI_LOOPBACK_CS_CTRL_GPIO_PIN=28