A switch can be defined as a Switch or an Outlet. Both types have the same set of options available to them.

The following configuration is available for switches:

{
  "c": { 
    "io": [ [ [ 12, 13 ], 2 ], [ [ 0 ], 6 ] ],
    "l": 13, "b": [ [ 0, 5 ] ]
  },
  "a": [{
    "t": 1,
    "d": 3600,
    "s": 5,
    "0": { "r": [ [ 12, 0 ] ] },
    "1": { "r": [ [ 12, 1 ] ] },
    "b": [ [ 0 ] ]
  }]
}

This is an example of a Sonoff Basic unit configured as a switch ("t": 1), using GPIO 12 as the binary output to control the power relay in the device. The LED is defined as being connected to GPIO 13. A button is also defined for entering Setup Mode when the button on GPIO 0 is pressed for longer then 8 seconds.

A binary input is configured as being connected to GPIO 0 and two button actions are defined; "0" & "1". The first press of the button invokes action "0" and sets the GPIO 12 to a logic low (0). The second press of the button invokes action "1" and sets the output to a logic high (1).

Set the type to 2 ("t": 2) if you would prefer the switch to appear in HomeKit as an Outlet e.g. when you have the device controlling a power socket or power strip.

The switch also has a maximum use time of 1 hour ("d": 3600) and its initial state when the service is powered on or rebooted will be the last state before it was rebooted ("s":5).

NOTE: The following options are not needed in this example as they are the default options but are included to make the example more readable: "t": 1 & "v": 0

A switch has two actions. The Binary Outputs "r": [ ] for each should be configured to attain the desired state.

Maximum use time is defined by the "d" key contained within the service object.

This option limits the maximum amount of time that the service can be in the ON state. The default is no limit.

When the timer is enabled then the service will be turned OFF after the maximum use time has elapsed.

NOTE: The value is an integer so no decimals :-)

The list of Service Notifications "m" values supported are:

See the general Service Notifications section for details of how to configure these notifications.

Binary Inputs "b" are supported by this service.

See Binary Inputs for details on how to define this mandatory option.

State inputs "f[n]" & Status Inputs "g[n]" are supported by this service. The supported list is:

Refer to State Inputs for more detail and examples.

ICMP Ping inputs "p[n]" and "q[n]" are supported by this service. The supported list is:

Refer to ICMP Ping Inputs for more detail.

The Initial Lock State about Service and Physical controls.

The Initial State key is supported by this service. Refer to Initial State for details of the available values.