$ ping rpi4

$ ssh pi@rpi4

$ lsmod
$lsmod | grep spi

# raspi-config
  3 Interface options | I4 SPI | Yes | OK | Finish

$lsmod | grep spi  -->  spidev
ls -l /dev/spi*    -->  /dev/spidev0.0 & /dev/spidev0.1


