What kind of hardware used

[Fraser86]

Can you help me understand what type of hardware can be used for digital inputs. I have the relay outputs working and temperature but i dont understand how exactly the digital inputs come in.
Please shed some light

[kwindrem]

RpiGpioSetup defines 5 digital inputs on GPIO pins. Refer to gpio_list in the package for those definitions.

Those inputs are active low. So connecting the pin to ground will activate that function. Most functions allow the input polarity to be inverted.

Isolating the input from the outside world is highly recommended to prevent damage to the CPU chip. Isolation can be in the form of a relay or an otto-isolator. In both cases, the input will need a power source to close the relay or stimulate the otto-isolator when the source of the input activates.

You can probably skip isolation if the source is close and can provide a reliable logic low to the GPIO pin. Clamping diodes between the pin and ground and the 3.3 volt supply is advised.