Using Arduino HID on non-v0 platforms is useful if you need a simple and primitive keyboard/mouse emulation device. For example, for Apple UEFI or when used with a hardware KVM switch wich [does not recognize composite HID](https://github.com/pikvm/pikvm/issues/7). You can also use the Arduino HID to emulate the PS/2 keyboard.
To select the PS/2 firmware, you need to follow the instructions for USB, but with one exception. Befor `make` you need to edit file `platformio.ini`. Open it and find these lines:
```ini
[_common]
build_flags =
-DHID_PS2_KBD_CLOCK_PIN=7
-DHID_PS2_KBD_DATA_PIN=5
-DHID_USB_CHECK_ENDPOINT
# ----- The default config with dynamic switching -----
By default, the firmware works with USB HID and supports dynamic mode switching. You can choose one of the other modes by commenting out some lines and uncomenting others. For example, you can use a USB mouse and PS/2 keyboard:
```ini
...
# ----- The default config with dynamic switching -----
Next, you need to connect the Arduino pins to the female PS/2 port of your motherboard. Choose the purple port. If your motherboard only have one port, it's probably universal and can be used either for the keyboard or for the mouse. Most likely, it is painted in two colors: green and purple. You can use it either.
**Connect VIN pin of Arduino to any Raspberry's 5v pin for PS/2 only device. But you don't need to connect the Arduino VIN pin if you connected USB (Arduino will get power through it).**