I would like to have some GPIOs on my OpenWRT device, without the need to open the device and gain access to the onboard GPIOs. So I would like to have some GPIOs over an USB Adapter. But I can't find anything usable.
It would be perfekt to have an USB to GPIO + UART Adapter / IC which is working well with OpenWRT.
There is a firmware (whose name I cannot remember) that makes an Arduino act as an external GPIO controller, through the USB connection, and can easily be programmed from a library that you install on the router. And an Arduino nano can be fed from the same USB connection.