GPIO (Relays and Digital Inputs): J21

The socket J21 provides an 8-channel relay controller and 8 digital inputs.

Pinout

Relay 1 to Relay 8 are the control outputs for up to 8 relays. These switch to ground:

In 1 to In 8 are digital inputs. These can be used, for example, to detect the presence of a voltage or to check the state of a relay or button. The inputs are protected against overvoltage and ESD. The threshold voltage is approximately 2.7V.

Control via App

In the app, relays and digital inputs are provided via the gpio driver and can be controlled, for example, using the Toggle widget.

A relay output can be switched on for a specific duration. For example, a Button widget can be used for this. The command value specifies the state to switch to and the duration of activation, e.g., true,5000 to turn on the output for 5 seconds: