Update gpio.md

pages/gpio.md

@@ -166,3 +166,6 @@ SUBSYSTEM=="usb", ATTR{idVendor}=="16c0", ATTR{idProduct}=="05df", MODE="666"
 ```
 
 Channels should not use duplicate physical numbers. The driver supports saving state between KVMD restarts (meaning `initial=null`).
+
+### ezCoo KVM switch
+You can use GPIO to control switch port switching. This usually requires the use of relays and buttons, but for the [ezCoo switch](https://github.com/pikvm/pikvm/blob/master/pages/ezcoo.md), there is a special driver that simulates GPIO by sending commands to the switch over the serial port. So you can make a menu in Pi-KVM to control the multiport switch.