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User Manual

User Manual

Mount Park Sensor documentation

Mount Park Sensor — User Manual

Wireless telescope position safety sensor for roll-off roof observatories

Table of Contents

  1. Introduction
  2. What's in the Box
  3. Physical Installation
  4. Initial Setup
  5. Web Interface Reference
  6. Setting the Safe Position
  7. DragonLAIR Integration
  8. ASCOM Alpaca Standalone Use
  9. Firmware Updates
  10. Troubleshooting
  11. Technical Specifications

Introduction

The Mount Park Sensor is a wireless safety device that prevents your roll-off roof from moving unless your telescope is in a safe park position. Unlike reflective sensors that require precise beam alignment, the Mount Park Sensor uses an onboard accelerometer to measure the telescope's actual orientation—no alignment, no drift, no cables to run.

How It Works

The sensor measures pitch and roll angles using a BMA400 accelerometer. You park your telescope, tell the sensor "this is safe," and it remembers that exact orientation. When the telescope returns to that position (within your configured tolerance), the sensor reports safe. Any other position reports unsafe.

The sensor communicates over WiFi, syncing with your DragonLAIR controller automatically or functioning as a standalone ASCOM Alpaca Switch device for use with imaging software.

Key Features

  • Accelerometer-based detection—no beam alignment required
  • Wireless operation—no cables to the mount
  • Automatic DragonLAIR discovery—zero configuration required
  • ASCOM Alpaca compatible—works with N.I.N.A., SGP, and other software
  • Configurable tolerance—adjust sensitivity to match your mount's parking precision
  • No LEDs—dark operation for astronomy use
  • Settings persist across power loss—saved to flash memory

What's in the Box

  • Mount Park Sensor (with integrated WiFi antenna)
  • USB-C power cable

Physical Installation

Mounting Location

The Mount Park Sensor mounts in any standard finder shoe on your telescope. The enclosure is shaped to fit both Vixen-style and Synta-style dovetails.

Recommended mounting locations:

  • Finder shoe on the telescope tube
  • Finder shoe on the mount saddle
  • Any position that moves with the telescope

The sensor can be mounted in any orientation—it calibrates to whatever position it's in when you set the safe position.

Power Connection

Connect the USB-C cable to any USB power source:

  • Computer USB port (USB 2.0 or 3.0)
  • Phone charger
  • USB hub
  • Any USB power adapter

The sensor draws approximately 1W—well under what any standard USB port provides. No special power delivery (USB-PD) or high-power USB is required.

Power Source Recommendations

For permanent installations, a dedicated USB power supply or powered USB hub is more reliable than a computer's USB port. This ensures the sensor stays powered even if the computer is shut down or restarted.

Initial Setup

Step 1: Power On and Connect to the Sensor's WiFi

When first powered on (or after a factory reset), the sensor creates its own WiFi access point:

Setting Value
Network Name (SSID) mountsensor-XXXXXXXXXXXX
Password darkdragons
IP Address 192.168.4.1

The XXXXXXXXXXXX portion is your sensor's unique serial number, which is also printed on the device.

Connect to this network using your phone, tablet, or computer.

Important: Many phones will automatically disconnect from the sensor's network because it doesn't have internet access. If this happens:

  • On iPhone: Tap the (i) next to the network and disable "Auto-Join" for your regular network temporarily
  • On Android: Look for "Stay connected" or disable mobile data temporarily
  • On computer: This usually isn't an issue

Step 2: Access the Web Interface

Open a browser and navigate to:

http://192.168.4.1

You'll see the Mount Park Sensor web interface with three tabs: Control, Settings, and Update.

Step 3: Connect to Your Observatory WiFi

  1. Click the WiFi icon (📶) in the top-right corner of the header bar

  2. A dropdown appears showing current network information

  3. Click Scan to search for available WiFi networks

  4. Select your observatory network from the list

  5. Enter your WiFi password when prompted

  6. Click Connect

The sensor saves these settings and connects to your network. The access point turns off once connected.

Before disconnecting from the sensor's access point, note the serial number—you'll use it to find the sensor on your network.

Step 4: Find the Sensor on Your Network

Once the sensor joins your WiFi network, you can access it using mDNS:

http://mountsensor-XXXXXXXXXXXX.local

Replace XXXXXXXXXXXX with your sensor's serial number.

If mDNS doesn't work on your network:

  • Check your router's admin page for connected devices
  • Use a network scanner app (like Fing) to find devices
  • The sensor's MAC address starts with 3C:84:27

The sensor's IP address is also shown in the WiFi dropdown menu once connected.

Web Interface Reference

The web interface has three tabs: Control, Settings, and Update.

Control Tab

The Control tab shows real-time status and allows you to set the safe position.

Device Status Display:

Field Description
Is Safe to Move? Yes or No—whether the telescope is in the safe position
Pitch Current pitch angle in degrees
Roll Current roll angle in degrees
Serial Number Unique identifier for this sensor
Firmware Version Currently installed firmware

SET CURRENT POSITION AS PARKED Button: Click this button when your telescope is in its safe park position. The sensor saves the current pitch and roll values as the "safe" reference point.

QR Code: Scan with your phone to quickly open the web interface on a mobile device.

WiFi Icon (top-right): Click to view network status or change WiFi settings.

The WiFi dropdown shows:

  • Current SSID (network name)
  • IP address
  • MAC address
  • WiFi channel
  • DNS server
  • Gateway
  • Subnet mask
  • RSSI (signal strength in dB)
  • Scan button (find other networks)
  • Disconnect button

Settings Tab

The Settings tab allows you to configure the sensor's behavior.

FACTORY RESET Button: Resets all settings to defaults, including WiFi configuration. The sensor will return to access point mode after reset.

Name: A friendly name for this sensor. This name appears in:

  • The web interface header
  • DragonLAIR device list
  • ASCOM device name

Default is "MountSensor". Change it to something descriptive like "Pier1-RC8" or "NorthScope" if you have multiple sensors.

Draco Token: Reserved for future cloud integration. Leave blank for now.

Pitch / Roll: The saved safe position values. These are set automatically when you click "SET CURRENT POSITION AS PARKED" on the Control tab. You can also edit them manually here if needed.

Pitch Allowed Error +/- and Roll Allowed Error +/-: The tolerance (in degrees) for determining safe vs. unsafe.

  • Default: ±1°
  • Recommended: ±5° for most setups

If the current pitch is within ±(Pitch Allowed Error) of the saved pitch, AND the current roll is within ±(Roll Allowed Error) of the saved roll, the sensor reports safe.

How to choose tolerance:

  • Tighter (1-2°): Use if your mount parks with high precision and you want strict safety
  • Looser (5-10°): Use if your mount has some variation in park position, or if you want a larger "safe zone"

The purpose of this sensor is to prevent the roof from moving when the telescope is above the roofline where it could be hit. A ±5° tolerance is sufficient for this purpose while accommodating normal mount parking variation.

SAVE Button: Saves all settings changes. Settings are stored in flash memory and persist across power cycles.

Update Tab

The Update tab allows you to install firmware updates.

To update firmware:

  1. Download the firmware file from Dark Dragons Astronomy (.bin file, less than 4MB)

  2. Drag and drop the file onto the upload area, or click to browse

  3. Click UPDATE

  4. Wait for the update to complete—do not disconnect power during the update

The sensor will reboot automatically after a successful update.

Setting the Safe Position

Basic Procedure

  1. Park your telescope in its designated safe position

    • This should be where the telescope is completely clear of the roof's path
    • Most mounts have a "Park" position—use it
    • The telescope can be pointing anywhere; you're teaching the sensor what "parked" looks like

  2. Open the web interface on the Control tab

  3. Click "SET CURRENT POSITION AS PARKED"

    • The sensor reads the current pitch and roll angles
    • These become the reference values for "safe"

  4. Verify it's working:

    • Move the telescope slightly—status should change to "No"
    • Return to park—status should change to "Yes"

Tips for Reliable Operation

Consistent parking: The more consistently your mount returns to its park position, the tighter you can set the tolerance. If your mount parks within ±1°, you can use the default tolerance. If it varies by ±3°, set tolerance to at least ±5°.

Don't overthink the position: The sensor measures orientation, not absolute position. It doesn't care where the telescope is pointing in the sky—it only cares about the physical angle of the sensor itself.

Re-calibrate after adjustments: If you move the sensor to a different finder shoe, or adjust how it sits in the shoe, re-set the safe position.

DragonLAIR Integration

The Mount Park Sensor is designed to work seamlessly with DragonLAIR controllers.

Automatic Discovery

When both devices are on the same network, the DragonLAIR automatically discovers the Mount Park Sensor. No IP addresses to enter, no pairing process.

You can verify discovery on the DragonLAIR:

  1. Open the DragonLAIR web interface
  2. Go to Control → Network tab
  3. The "All Dark Dragons Devices" table shows all discovered devices
  4. Your Mount Park Sensor appears with its name, serial number, IP address, firmware version, last seen time, and current status

Enabling the Sensor

Discovery doesn't automatically enable the safety interlock. You must enable it:

  1. Open the DragonLAIR web interface
  2. Go to Settings
  3. Scroll down to Mount Park Sensors
  4. Find your sensor in the list (shown as "Name - SerialNumber")
  5. Toggle the switch to enable it

Safety Behavior

Once enabled:

  • The roof will not move unless the sensor reports safe
  • Safety sensors take priority over all other controls
  • If the sensor reports unsafe, roof movement is blocked regardless of other conditions
  • If the sensor loses connection, the DragonLAIR treats it as unsafe (fail-safe behavior)

Multiple Sensors

The DragonLAIR can work with multiple Mount Park Sensors—useful for observatories with more than one telescope. Each sensor appears separately in the Settings list, and you can enable/disable them individually.

All enabled sensors must report safe for the roof to move.

Status Display

On the DragonLAIR Control tab:

  • SAFE TO MOVE indicator shows the combined status of all enabled safety sensors
  • The Network tab shows individual sensor status and "Last Seen" timestamps

ASCOM Alpaca Standalone Use

The Mount Park Sensor works as an ASCOM Alpaca device even without a DragonLAIR. This allows you to use it with N.I.N.A., Sequence Generator Pro, Voyager, or any ASCOM-compatible software.

Important: If you're using a DragonLAIR controller, you don't need to configure anything in your imaging software. The DragonLAIR handles all safety gating automatically—it simply won't move the roof unless the sensor reports safe. The ASCOM interface is there if you want it, but it's not required for normal operation.

If you're using a different roof controller (not DragonLAIR), you'll need to implement the safety check yourself in your imaging software. Query the sensor's switch state and gate your roof open/close commands based on the result.

Device Type

The sensor implements the ASCOM Switch interface (read-only).

Property Value
Switch ID 0
State true = safe, false = unsafe

Discovery

The sensor supports Alpaca Discovery protocol. Software that implements Alpaca discovery (like N.I.N.A.) can find the sensor automatically.

Manual Connection

If automatic discovery doesn't work:

Setting Value
IP Address (varies—check your network)
Port 80
Device Type Switch
Device Number 0

Polling Recommendation

Poll the switch state once per second or less. Faster polling provides no practical benefit for detecting telescope position changes and just adds unnecessary network traffic.

Using in Imaging Software

DragonLAIR users: You don't need to set this up unless you want additional software-side checks or are doing complex automation logic. The DragonLAIR already prevents roof movement when the sensor reports unsafe.

Non-DragonLAIR users: You'll need to query the sensor and implement safety logic in your automation sequences.

N.I.N.A.:

  1. Go to Equipment → Switch
  2. Click the search icon to discover Alpaca devices
  3. Select the Mount Park Sensor from the list
  4. Connect
  5. Use the switch state in your Advanced Sequencer to gate roof operations

SGP / Voyager / Other: Add the sensor as an ASCOM Alpaca Switch device using the IP and port above. Use the switch state in your automation scripts to verify park position before moving the roof.

Example Logic (Non-DragonLAIR Users)

If you're using a third-party roof controller, here's the basic pattern for your automation scripts:

IF MountParkSensor.Switch[0] = True THEN
    Roof.Open()
ELSE
    Log("Telescope not parked - aborting roof operation")
END IF

Firmware Updates

Dark Dragons Astronomy releases firmware updates to add features and fix bugs.

Checking Your Version

The current firmware version is displayed on:

  • The Control tab (under Device Status)
  • The DragonLAIR's Network tab (in the device list)

Update Procedure

  1. Download the latest firmware from Dark Dragons Astronomy

    • File format: .bin
    • Maximum size: 4MB

  2. Open the sensor's web interface

  3. Go to the Update tab

  4. Drag and drop the firmware file onto the upload area (or click to browse)

  5. Click UPDATE

  6. Wait for completion—the sensor will reboot automatically

Do not disconnect power during the update process.

After Updating

Your settings (WiFi, safe position, tolerance, name) are preserved across updates. Verify the new version number on the Control tab.

Troubleshooting

Can't Connect to Sensor's Access Point

Symptoms: The mountsensor-XXXXXXXXXXXX network doesn't appear, or you can't connect.

Solutions:

  • Ensure the sensor is powered (USB-C connected to a working power source)
  • Wait 30 seconds after power-on for the access point to start
  • If the sensor was previously configured for a WiFi network, it won't create an access point unless that network is unavailable
  • Try a factory reset (see below)

Phone Keeps Disconnecting from Sensor WiFi

Symptom: Your phone connects briefly, then switches back to your regular WiFi.

Cause: Phones prefer networks with internet access.

Solutions:

  • Disable auto-join on your regular network temporarily
  • Disable mobile data temporarily
  • Use a laptop instead (usually more reliable)
  • Work quickly—get the WiFi configured before auto-disconnect

Can't Find Sensor After WiFi Configuration

Symptoms: The sensor joined your network but you can't access it.

Solutions:

  1. Try mDNS: http://mountsensor-XXXXXXXXXXXX.local
  2. Check your router's DHCP client list for new devices
  3. Use a network scanner app (Fing, Advanced IP Scanner)
  4. Look for MAC addresses starting with 3C:84:27
  5. If all else fails, factory reset and try again

Sensor Shows "Not Safe" When Telescope Is Parked

Symptoms: The telescope is in its park position but the sensor says unsafe.

Solutions:

  1. Re-set the safe position: The mount may have shifted slightly. Click "SET CURRENT POSITION AS PARKED" again.
  2. Increase tolerance: Go to Settings and increase the Pitch/Roll Allowed Error. Try ±5° instead of ±1°.
  3. Check mount parking consistency: Park the mount several times and watch the pitch/roll values. If they vary by more than your tolerance, increase the tolerance accordingly.

DragonLAIR Doesn't Show the Sensor

Symptoms: The sensor works in its own web interface but doesn't appear in DragonLAIR.

Solutions:

  1. Verify both devices are on the same network/subnet
  2. Check the DragonLAIR's Network tab—if the sensor appears there but not in Settings, scroll down further in Settings
  3. Restart the sensor (unplug and replug power)
  4. Check for firewall rules blocking local network discovery

DragonLAIR Shows "Not Safe to Move" But Sensor Says Safe

Symptoms: Mismatch between sensor status and DragonLAIR status.

Possible causes:

  1. Sensor not enabled: Go to DragonLAIR Settings → Mount Park Sensors and ensure your sensor is toggled on
  2. Connection lost: Check "Last Seen" on the DragonLAIR Network tab. If it's old, the DragonLAIR has lost contact with the sensor (and treats it as unsafe)
  3. Multiple sensors: If you have multiple sensors enabled, ALL must report safe

Factory Reset

If you need to start over:

  1. Open the sensor's web interface
  2. Go to the Settings tab
  3. Click FACTORY RESET
  4. Confirm the reset

The sensor erases all settings (including WiFi) and restarts in access point mode. You'll need to reconfigure WiFi and set the safe position again.

Note: You need network access to the sensor to perform a factory reset. If you can't access the sensor at all, contact Dark Dragons Astronomy support.

Technical Specifications

Sensor

Specification Value
Position Sensing BMA400 accelerometer
Safe Position Tolerance Configurable, ±1° to ±90°
Default Tolerance ±1° (±5° recommended)
Update Rate 1 Hz (web interface), instant (state changes)

Connectivity

Specification Value
WiFi 2.4 GHz (802.11 b/g/n)
Antenna Integrated
mDNS mountsensor-XXXXXXXXXXXX.local
ASCOM Interface Alpaca Switch (read-only)
Port 80

Power

Specification Value
Connector USB-C
Input Voltage 5V (standard USB)
Power Draw ~1W
Special Requirements None (no USB-PD required)
Settings Storage Flash (persists across power loss)

Physical

Specification Value
Mounting Vixen / Synta finder shoe dovetail
Length ~2.5 inches
LEDs None (dark for astronomy)
Operating Temperature 10°F to 105°F (-12°C to 40°C)

Access Point Mode (Initial Setup)

Setting Value
SSID mountsensor-XXXXXXXXXXXX
Password darkdragons
IP Address 192.168.4.1

Support

Discord Community: https://darkdragonsastro.com/discord

Email: support@darkdragonsastro.com

Documentation: https://darkdragonsastro.com/support

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