Altitude drive system using Argo and PIC microcontroller

[kustard]

Hi all,

A bit of history first, last year I bought an Orion 14" Go-to Truss Dob. Optics are great but it has suffered from Azimuth drive problems. After back and forth with Orion and local servicing with no complete fix I decided to remove all the controls and turn the scope back into a basic push-to scope with an Argo Navis.

After installing the Argo the scope works flawlessly. The only issue I was having was aligning the scope due to the Altitude axis being quite stiff. Fortunately I still had the altitude motor connected and could move the scope in altitude with a small control that used a variable voltage supply and a toggle switch.

"I can do better than this!" I said to myself. So I contacted Gary at Wildcard and he pointed me to the serial port and SkyComm protocol. I then went and bought some PIC microcontroller SBC's and other bits (LCD's, keypads, a DSO) and a few days of coding later (I've coded PIC controllers before) I have a demonstrable version of a single axis scope controller.

The system connects to the Argo via RS232 @ 19200 baud. The system polls the Argo for guide data and drives the axis motor using a software generated PWM signal. Direction is provided by toggling the output via two relays (SPDT). The system drives the motor at varying speeds based on how much the scope needs to move. The system then "tracks" the object by moving the scope when the object drifts by a small amount. Selecting a new object on the Argo will cause the system to drive the Altitude to the new object. I still have to push the scope in azimuth but I can live with that

I've made it so that you can operate the scope without the Argo connected and if there is any hiccup in data the system returns to a "manual mode" that stops automatic tracking to prevent the scope from driving wild.

I've made a very dodgy video and uploaded it to YouTube and you can check out to see a demonstration of the project. Sorry for my poor video skills

Please feel free to offer opinions or ask questions.

Cheers,

Simon

[kustard]

Hi

The project has been best tested in my living room and I've put it into a box (I don't have a proper man's cave full of lovely tools so it's a bit hacked).

Cheers,

Simon

[Astro_king]

Good work My friend.. hours well spent!

[OneEyedSam]

hi...good job. Do you know if the serial ports ok Argo are 3.3 or 5v?