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If a characteristic value is updated with the same value, it is ignored.
Only exception is the programmable switch event characteristic, which
requires that clients are notified even when updating with the same value.

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Nov 25, 2019
Jun 4, 2019
Apr 28, 2016


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hc is a lightweight framework to develop HomeKit accessories in Go. It abstracts the HomeKit Accessory Protocol (HAP) and makes it easy to work with services and characteristics.

hc handles the underlying communication between HomeKit accessories and clients. You can focus on implementing the business logic for your accessory, without having to worry about the protocol.

Here are some projects which use hc.

What is HomeKit?

HomeKit is a set of protocols and libraries from Apple. It is used by Apple's platforms to communicate with smart home appliances. A non-commercial version of the documentation is now available on the HomeKit developer website.

HomeKit is fully integrated into iOS since iOS 8. Developers can use HomeKit.framework to communicate with accessories using high-level APIs.

I've developed the Home+ app to control HomeKit accessories from iPhone, iPad, and Apple Watch. If you want to support hc, please purchase Home from the App Store. That would be awesome. ❤️

Checkout the official website.


Getting Started

  1. Install and set up Go

  2. Create your own HomeKit accessory or clone an existing one (e.g. hklight)

     cd $GOPATH/src
     # Clone project
     git clone && cd hklight
     # Run the project
     make run
  3. Pair with your HomeKit App of choice (e.g. Home)

Go Modules

hc supports Go module since v1.0.0. Make sure to set the environment variable GO111MODULE=on.


See _example for a variety of examples.

Basic switch accessory

Create a simple on/off switch, which is accessible via IP and secured using the pin 00102003.

package main

import (

func main() {
    // create an accessory
    info := accessory.Info{Name: "Lamp"}
    ac := accessory.NewSwitch(info)
    // configure the ip transport
    config := hc.Config{Pin: "00102003"}
    t, err := hc.NewIPTransport(config, ac.Accessory)
    if err != nil {

You can define more specific accessory info, if you want.

info := accessory.Info{
    Name: "Lamp",
    SerialNumber: "051AC-23AAM1",
    Manufacturer: "Apple",
    Model: "AB",
    FirmwareRevision: "1.0.1",


The library provides callback functions, which let you know when a clients updates a characteristic value. The following example shows how to get notified when the On characteristic value changes.

ac.Switch.On.OnValueRemoteUpdate(func(on bool) {
    if on == true {
        log.Println("Switch is on")
    } else {
        log.Println("Switch is off")

When the switch is turned on "the analog way", you should set the state of the accessory.


Multiple Accessories

When you create an IP transport, you can specify more than one accessory like this

bridge := accessory.NewBridge(...)
outlet := accessory.NewOutlet(...)
lightbulb := accessory.NewColoredLightbulb(...)

hc.NewIPTransport(config, bridge, outlet.Accessory, lightbulb.Accessory)

By doing so, the bridge accessory will become a HomeKit bridge. The outlet and lightbulb are the bridged accessories.

When adding the accessories to HomeKit, iOS only shows the bridge accessory. Once the bridge was added, the other accessories appear automatically.

HomeKit requires that every accessory has a unique id, which must not change between system restarts. hc automatically assigns the ids for you based on the order in which the accessories are added to the bridge.

But I recommend that you specify the accessory id yourself, via the accessory.Config.ID field, like this.

bridge := accessory.NewBridge(accessory.Info{Name: "Bridge", ID: 1})
outlet := accessory.NewOutlet(accessory.Info{Name: "Outlet", ID: 2})
lightbulb := accessory.NewColoredLightbulb(accessory.Info{Name: "Light", ID: 3})

Accessory Architecture

HomeKit uses a hierarchical architecture to define accessories, services and characeristics. At the root level there is an accessory. Every accessory contains services. And every service contains characteristics.

For example a lightbulb accessory contains a lightbulb service. This service contains characteristics like on and brightness.

There are predefined accessories, services and characteristics available in HomeKit. Those types are defined in the packages accessory, service, characteristic.


Matthias Hochgatterer





hc is available under the Apache License 2.0 license. See the LICENSE file for more info.

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