alpaca-switch

Unified ASCOM Alpaca Switch driver that exposes multiple hardware backends as a single Switch device to astronomy software such as N.I.N.A.

Currently supports two backends, all visible as numbered switches inside one ASCOM device. Mi switches to turn devices on and off and Hikvision cameras to turn off IR lights to prevent stray lights for astrophotography.

Backend	Hardware	Protocol
Xiaomi Mi	Mi Smart Plug (Wi-Fi power switches)	Xiaomi UDP protocol, AES-CBC encryption
Hikvision	IP camera IR illuminators	Hikvision ISAPI over HTTP, Digest auth

Switch IDs are assigned in the order backends are listed: Mi plugs first (IDs 0–N), then Hikvision cameras (IDs N+1–M).

Requirements

• Go 1.22 or later
• Xiaomi Mi plugs: device IP and 32-character hex token (obtainable with miio)
• Hikvision cameras: camera IP, admin credentials, and Configuration → System → Maintenance → System Service → Hardware enabled in the camera web UI
  • Tested on: DS-2CD2343G0-I, DS-2CD2335-I
  • Supports optional port in host field, e.g. "192.168.1.3:65005"

Quick Start

1. Configure

Copy config/settings.json.example to config/settings.json and fill in your device details:

{
    "alpaca_port": 11111,
    "mi_devices": [
        {
            "ip": "192.168.1.100",
            "token": "your32hexcharactertoken00000000",
            "name": "12V Power",
            "description": "12V dew heater power",
            "min": 0,
            "max": 1,
            "step": 1,
            "canwrite": true,
            "value": 0
        }
    ],
    "hikvision_cameras": [
        {
            "host": "192.168.1.4",
            "username": "admin",
            "password": "yourpassword",
            "name": "Backyard IR",
            "description": "Control IR light on backyard security camera",
            "uniqueid": "00000000-0000-0000-0000-000000000001",
            "value": 0
        }
    ]
}

Add as many entries to each array as needed.

2. Build

go build -o alpaca-switch.exe .

3. Run

./alpaca-switch.exe

The driver listens on port 11111 (standard ASCOM Alpaca port) and responds to ASCOM discovery broadcasts on UDP port 32227.

4. Connect from N.I.N.A.

1. Open N.I.N.A. → Equipment → Switch
2. Click the Scan for devices
3. In the dropdown list under the sub heading ASCOM Alpaca select the Alpaca Switch Controller item
4. Click Connect — all switches appear by name

Configuration reference

Top-level

Field	Description
alpaca_port	HTTP API port (default: 11111)
mi_devices	Array of Xiaomi Mi smart plug configs
hikvision_cameras	Array of Hikvision camera configs

Xiaomi Mi device fields

Field	Description
ip	Device IP address
token	32-character hex authentication token
name	Title shown in NINA
description	Subtitle shown in NINA (optional; falls back to name)
min / max / step	Value range (0/1/1 for on/off switches)
canwrite	false to make the switch read-only in NINA
value	Cached last-known state (0=off, 1=on)

Hikvision camera fields

Field	Description
host	Camera IP address, optionally with port: "192.168.1.4" or "192.168.1.3:65005"
username	Camera admin username (usually admin)
password	Camera password
name	Title shown in NINA
description	Subtitle shown in NINA (optional; falls back to "<name> IR illuminator")
uniqueid	Stable UUID for the ASCOM device (any unique value, e.g. "00000000-0000-0000-0000-000000000001")
value	Cached last-known IR state (0=off, 1=on)

Project structure

alpaca-switch/
├── main.go                        # Entry point: loads config, wires backends, starts server
├── backend/
│   ├── backend.go                 # SwitchBackend interface + Router (ID mapping)
│   ├── mi/
│   │   ├── mi.go                  # Xiaomi Mi plug state management
│   │   └── xiaomi.go              # Xiaomi UDP protocol (AES-CBC encrypted)
│   └── hikvision/
│       └── hikvision.go           # Hikvision ISAPI IR control (HTTP Digest auth)
├── server/
│   ├── api.go                     # HTTP server, request helpers, response builder
│   ├── discovery.go               # ASCOM Alpaca UDP discovery (port 32227)
│   ├── management.go              # /management/* endpoints
│   ├── common.go                  # /api/v1/switch/0/connected, name, description…
│   ├── switch.go                  # /api/v1/switch/0/getswitch, setswitch…
│   └── types.go                   # ASCOM Alpaca response structs
└── config/
    ├── settings.json              # Your local config (excluded from git — contains credentials)
    └── settings.json.example      # Safe template to commit

Adding a new backend

1. Create backend/<name>/<name>.go implementing the backend.SwitchBackend interface
2. Add a config struct and load it in main.go
3. Pass the new backend to backend.NewRouter()

Notes

• config/settings.json is excluded from git because it contains device tokens and camera passwords. Commit settings.json.example instead.
• Hikvision IR state is read live from the camera each time NINA polls GetSwitch.
• Xiaomi plug state is refreshed on Connect and cached; updates are sent on each SetSwitch.
• Discovery binds to the primary outbound network interface to avoid NINA discovering the driver multiple times on multi-adapter machines.

References

• ASCOM Alpaca API Reference
• Hikvision ISAPI Documentation
• python-miio (Xiaomi token extraction)