It is much simpler than Kedei LCD as it is supported by fbtft and device overlay

  1. Update RPi kernel to latest by “rpi-update”

  2. Clone the waveshare device tree overlay git repository

  3. Copy waveshare-dtoverlays/waveshare35a-overlay.dtb from the repositroy to /boot/overlays/waveshare35a.dtbo

  4. Add dtoverlay=waveshare35a to /boot/config.txt

  5. Ensure SPI is enabled in /boot/config.txt

  6. Reboot and use /dev/fb1 as the device for graphical output

  7. For console output, add to /boot/cmdline:

     console=ttyAMA0,115200 fbcon=map:10 fbcon=font:ProFont6x11 consoleblank=0