Arduino ST4 telescope control

Telescope GOTO and autoguiding through ST-4 with an arduino

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The purpose of this project is to connect a telescope to a computer through the mount guide port (ST-4 port) using an arduino in order to cheaply add GOTO and autoguiding capabilities.

The ST-4 Port is easy to add to "low cost" motorized mounts like the EQ4 or EQ5, and the operation requires minimal modification to your shiny mount.

Hardest part is the code (Arduino sketch ~120 lines and ASCOM driver ~2600 lines), but I already wrote it for you :-)

Basically, you need to build the USB-ST4 interface described in the github project page and modify your control pad like explained here if it doesn't have an ST4 port.

Modifying the control pad means soldering and wiring an RJ12 socket to the pad buttons.

Once the hardware is done, you will need to install the ASCOM platform and the driver.

After this you can use a software like the open source stellarium to play with your telescope or PHD for astrophotography.

More details are available on the github project page.

Here is a small guide to use it with stellarium.

Sample video of the telescope moving:

  • 1 × Arduino For interfacing with USB
  • 1 × TLP521-4 optocoupler In order to isolate the arduino from the autoguide port
  • 2 × RJ12 socket 1 if your mount already has an ST4 port
  • 1 × RJ12 straight cable To connect the adapter and the mount
  • 1 × A case for the adapter Excepted if you prefer to see the bare electronics :-)

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Alexis wrote 06/30/2015 at 22:24 point

Congrats for this project!!!  I have an EQ5 whit dual axis. I add RJ-12 port to the handpad and guide whit the QHY5 ST4 port. Do you think that is possible to make a sort of goto whit it? 

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Kevin Ferrare wrote 07/01/2015 at 08:45 point

Thank you. I see that we have the same mount.

I think that It would be possible to do a GOTO with your camera if you can reverse engineer the protocol it uses to pulse guide the mount.

If you manage to do so, you could reuse most of the driver code, the only places that would need to be changed would be DeviceController.cs and the GUI for connection if it is not using serial.

Good luck, and keep me informed if you manage to adapt/extend the driver!

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stevenbauer10 wrote 02/23/2015 at 21:13 point

Great project! But I was wondering; why don't you use any current limiting resistors at the LEDs on the optocoupler?

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Kevin Ferrare wrote 02/23/2015 at 23:21 point

You are right, there should be a ~100Ω resistor between each digital pin of the arduino and the optocoupler (Forward voltage for the IR diodes of this model of optocoupler seems to be around ~1.15V depending on the current).

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