Translations:Wiren Board 5:Аппаратная часть/357/en
In the alternate general-purpose ADC mode (with current source disabled), the input is pulled down to the ground. In this case, a logical zero corresponds to the floating input, while logical high corresponds to the voltage across terminals higher than 2.5V.
In this mode one should connect external buttons, sensors, etc. between the Rx terminal and either "5V out" or positive power supply terminal.