EQFocuser – Instructions

EQFocuser Description

The EQFocuser started as a DIY project powered by Arduino and ASCOM.  It is completely compliant with ASCOM and so far this is the focuser that I’m using with my telescopes.  I have a couple of variations that are using different types of motor depending on the need.  The project is open source and you can download the drivers and sketch files here https://github.com/EverettQuebral/EQFocuser

Supported Stepper Motor Controller

Hardware Parts

  • 1 Arduino (Nano – $5.00, Uno – $8.00)
  • 1 Telescope specific bracket (I 3D printed mine)
  • Set of screws for your focuser
  • Aluminum Flexible Shaft Coupling ($1.50) (Please select the size for your focuser)
  • 2 Pull Up Switch (Optional)
  • 1 Variable Resistor (Optional)
  • 1 DHT11 (Temperature/Humidity) Sensor (Optional)

For EasyDriver or Adafruit Motor/Stepper/Servo Sheild

For ST35 or 28BYJ-48


Diagram Using ULN2003 Motor Driver

ULN 2003 Motor Driver

Diagram Using EasyDriver

EasyDriver Pins

The video above shows the NEMA 17 0.4AMP with 56.7oz.in torque

Github Location


Driver Download

You can download the latest Driver at the Release section https://github.com/EverettQuebral/EQFocuser/releases

3D Model Files

Available under the Resources folder

Also available at Thingiverse

16 thoughts on “EQFocuser – Instructions”

  1. Hi. Can you share the diagram of your connections using the Adafruit Moto shield ? Additionally, I have an issue which is the EQFocuser driver never picks up the Com port. In device manager I have it there as Com9. I am using Windows 10 the latest update. Thanks in advance and for sharing this for us starting. Ago

    1. I’m using the DHT sensor library by Adafruit, version 1.3.0
      You should be able to see that on the Arduino IDE (1.8.5) via Sketch -> Include Library -> Manage Library and seach for the DHT sensor library

  2. After installing all the required libraries, I have come to a stumbling block that I have been unable to resolve even with the help of google. I am encountering this error when uploading the sketch:

    Arduino: 1.8.5 (Windows 10), Board: “Arduino/Genuino Uno”

    C:\Users\dan.doyle\Documents\Arduino\EQFocuser\EQFocuser.ino: In function ‘void humidityTemperatureReport()’:

    EQFocuser:278: error: expected primary-expression before ‘.’ token

    chkSensor = DHT.read11(DHT11_PIN);


    EQFocuser:280: error: ‘DHTLIB_OK’ was not declared in this scope

    case DHTLIB_OK:


    EQFocuser:282: error: expected primary-expression before ‘.’ token

    Serial.print(DHT.temperature, 1);


    EQFocuser:286: error: expected primary-expression before ‘.’ token

    Serial.print(DHT.humidity, 1);


    EQFocuser:290: error: ‘DHTLIB_ERROR_CHECKSUM’ was not declared in this scope



    EQFocuser:298: error: ‘DHTLIB_ERROR_TIMEOUT’ was not declared in this scope



    exit status 1
    expected primary-expression before ‘.’ token

    Invalid version found: 1.04
    Invalid version found: 1.04

    This report would have more information with
    “Show verbose output during compilation”

    Any assistance would be greatly appreciated!


    1. FYI, I’m not a programmer and have never worked with Arduinos before, so I’m surprised I’ve gotten this far.

      1. What sketch file are you using?

        I’m assuming that you are using either one of the last 2 because they are using the DHT library.

  3. Great work, many thanks for your efforts!
    Managed to compile EQFocuserStepper.ino and upload it to Arduino Uno, DHTLib library did the trick with the DHT part of the code instead of the Adafruit library.(https://github.com/RobTillaart/Arduino/tree/master/libraries/DHTlib).

    With the temperature & humidity part I however hit another speed bump – there’s no temperature & humidity values visible in the 1.0.8 driver window. Using the “k” command through the Arduino IDE serial monitor returns correct values in the serial monitor, and connection to motors works fine through the 1.0.8 driver. But there’s no temperature nor humidity values coming through. Also hitting the “advanced” button in the driver results only “444” being displayed in the humidity value window in the driver, but won’t open any further settings. Would you be able to help with any pointers how to get the temperature & humidity part working as well?

  4. Hi, I’m finishing your focuser for my newton.
    I also use stellarmate (raspberry), could it also work with INDI?

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