RoyK_Devonman
Posts: 4
Joined: Mon Jan 02, 2017 4:38 pm

Direct telescope control of Meade RA & Dec drives

Mon Jan 02, 2017 4:58 pm

Hi
I have been given a Meade 4504 Telescope, the hand controller is missing, has anyone been able to directly connect the Pi to the drive motors through the HBX socket. I would think I would need some kind of opto-isolator type interface. Or could I just find a way to drive the mount manually and use the Pi and a program like Stellarium to match up positioning to a PC.

Does anyone have any ideas, reading the forums there are a lot of switched on people out there, thankfully? I'm just getting to grips with the Pi 3 and thought the best way to get more involved with it was to find a good project to try.

Thanks. Roy

MikeDunn
Posts: 83
Joined: Wed Jul 01, 2015 6:58 pm

Re: Direct telescope control of Meade RA & Dec drives

Tue Jan 03, 2017 2:38 pm

Roy,

From a quick scan of the manual, all the clever bits are in the handset - none are in the two motor boxes. In my opinion, you're wasting your time trying to recreate the controls using a Pi.

Suggest you follow the advice you've already been given on Cloudy Nights & either buy a replacement handset off eBay or accept one of the offers of a free one ... :roll: Or, of course, find the handset with your family (and the rest of the bits you seem to be missing).

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scruss
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Location: Toronto, ON
Contact: Website

Re: Direct telescope control of Meade RA & Dec drives

Tue Jan 03, 2017 4:42 pm

It might be a lot of work, but people have done things like the Stellarduino, so it's more of a question of how big your appetite for a challenge might be.

I'm guessing the Meade handset does the clever calcs, and the interface just expects motor drive commands (pulses? durations?) and provides encoder output. Can you find a pinout of the telescope connector? Meade looks like they change specs fairly frequently, and there could be many variants.
‘Remember the Golden Rule of Selling: “Do not resort to violence.”’ — McGlashan.

RaspISteve
Posts: 98
Joined: Wed Oct 24, 2012 9:15 pm
Location: Cheltenham, UK

Re: Direct telescope control of Meade RA & Dec drives

Tue Jan 03, 2017 8:06 pm

Roy,
I've got a Pi controlling my Meade ETX125 driven via WiFi from Stellarium. The serial port connection from the Pi is buffered via an RS232 level shifter board and connects to the handset using the Meade serial cable. The eventual aim is to have the PiCam look down the scope and export the video to a browser. I also have this bit going but not all joined up.

I've compiled the necessary Meade interface driver (search for "TelescopeServer.tar", try https://github.com/fcsonline/node-telescope-server). This converts the Stellarium commands via network (up.down/left/right) to Meade LX200 commands (or other telescope types) then exports to the telescope via serial.

My researches around the subject found a document with a line warning about making any RS232 type connection to other than via the handset and NOT to connect to what appears to be another/similar serial interface on the base unit.

I have had the ETX125 apart and found the smarts drive looks like cheap 3 pole DC motors with a simple quadrature coding disc position encoder system. It does little else than count pulses from a scope being level/pointing north (some known datum) to where it needs to be. Slewing transition speed is controlled within the positioning control. I have not investigated the handset/base control interface but counting connections it's likely to be some serial protocol using proprietary signal levels.

Maybe not much help by heed the don't connect bit.
(169)
Share and Enjoy.

RoyK_Devonman
Posts: 4
Joined: Mon Jan 02, 2017 4:38 pm

Re: Direct telescope control of Meade RA & Dec drives

Sat Jan 07, 2017 4:29 pm

MikeDunn wrote:Roy,

From a quick scan of the manual, all the clever bits are in the handset - none are in the two motor boxes. In my opinion, you're wasting your time trying to recreate the controls using a Pi.

Suggest you follow the advice you've already been given on Cloudy Nights & either buy a replacement handset off eBay or accept one of the offers of a free one ... :roll: Or, of course, find the handset with your family (and the rest of the bits you seem to be missing).
Hi Mike thank you for your replay. The handset offered at Cloudy Nights see,s to be the wrong type. However, my son-in-law will be going on a 'hunt out the bits search' at his parents home in a few week so my fingers are crossed. The handsets listed at Meade are around £150, I rather have to spend this on trying to interface the Pi to the handset as has been suggested. Lets hope i can get sorted before the next Halley's comet pass or a supernova. :lol:

RoyK_Devonman
Posts: 4
Joined: Mon Jan 02, 2017 4:38 pm

Re: Direct telescope control of Meade RA & Dec drives

Sat Jan 07, 2017 4:39 pm

scruss wrote:It might be a lot of work, but people have done things like the Stellarduino, so it's more of a question of how big your appetite for a challenge might be.

I'm guessing the Meade handset does the clever calcs, and the interface just expects motor drive commands (pulses? durations?) and provides encoder output. Can you find a pinout of the telescope connector? Meade looks like they change specs fairly frequently, and there could be many variants.

Hi scruss

I am trying to find the pinouts of the handset, it like most information on-line there is a lot of it, of one piece of info contradicting another. The handset with the Meade I have is called a 494, a 497 will work as replacement as would an Audiostar handset. So if they are all compatible with the connection to the motor drives then they should all have common pins..I would hope. More investigating to do. Thanks for your reply I'll keep working on the problem and share what I find.

Roy

RoyK_Devonman
Posts: 4
Joined: Mon Jan 02, 2017 4:38 pm

Re: Direct telescope control of Meade RA & Dec drives

Sat Jan 07, 2017 5:12 pm

RaspISteve wrote:Roy,
I've got a Pi controlling my Meade ETX125 driven via WiFi from Stellarium. The serial port connection from the Pi is buffered via an RS232 level shifter board and connects to the handset using the Meade serial cable. The eventual aim is to have the PiCam look down the scope and export the video to a browser. I also have this bit going but not all joined up.

I've compiled the necessary Meade interface driver (search for "TelescopeServer.tar", try https://github.com/fcsonline/node-telescope-server). This converts the Stellarium commands via network (up.down/left/right) to Meade LX200 commands (or other telescope types) then exports to the telescope via serial.

My researches around the subject found a document with a line warning about making any RS232 type connection to other than via the handset and NOT to connect to what appears to be another/similar serial interface on the base unit.

I have had the ETX125 apart and found the smarts drive looks like cheap 3 pole DC motors with a simple quadrature coding disc position encoder system. It does little else than count pulses from a scope being level/pointing north (some known datum) to where it needs to be. Slewing transition speed is controlled within the positioning control. I have not investigated the handset/base control interface but counting connections it's likely to be some serial protocol using proprietary signal levels.

Maybe not much help by heed the don't connect bit.
(169)
Hi RaspISteve

Your post was a good help, for one it tell me I really need to get hold of a handset for the Meade 4504 aka DS 114-EQ4. The link you sent will be very useful when I can get this sorted so I hope my family will be able to locate it. I appreciate that you've done the hardwork taking things apart to give an idea of what is inside the motors. I will heed the 'don't connect'. I do wonder if this is to protect the motors or stop the use/production of 3rd party handsets. I will be patient and wait and see what my family can find.
Once I get the hardware sorted the use of Stellarium will be great, I have be using it for years so using it to point my telescope in the right direction would be good. The addition of the PiCam has always bee my intention, if only to be able to sit in the shed and watch and control the scope from inside a warm shed and also have a go at astro-photography. Whats life without a challenge :)

Roy

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bensimmo
Posts: 4068
Joined: Sun Dec 28, 2014 3:02 pm
Location: East Yorkshire

Re: Direct telescope control of Meade RA & Dec drives

Sat Jan 07, 2017 6:54 pm

RaspISteve wrote:Roy,
I've got a Pi controlling my Meade ETX125 driven via WiFi from Stellarium. The serial port connection from the Pi is buffered via an RS232 level shifter board and connects to the handset using the Meade serial cable. The eventual aim is to have the PiCam look down the scope and export the video to a browser. I also have this bit going but not all joined up.

I've compiled the necessary Meade interface driver (search for "TelescopeServer.tar", try https://github.com/fcsonline/node-telescope-server). This converts the Stellarium commands via network (up.down/left/right) to Meade LX200 commands (or other telescope types) then exports to the telescope via serial.

My researches around the subject found a document with a line warning about making any RS232 type connection to other than via the handset and NOT to connect to what appears to be another/similar serial interface on the base unit.

I have had the ETX125 apart and found the smarts drive looks like cheap 3 pole DC motors with a simple quadrature coding disc position encoder system. It does little else than count pulses from a scope being level/pointing north (some known datum) to where it needs to be. Slewing transition speed is controlled within the positioning control. I have not investigated the handset/base control interface but counting connections it's likely to be some serial protocol using proprietary signal levels.

Maybe not much help by heed the don't connect bit.
(169)
This may well be what I need if I get our etx setup like this :-)

jb63
Posts: 116
Joined: Mon May 11, 2015 6:41 pm

Re: Direct telescope control of Meade RA & Dec drives

Mon Jan 09, 2017 10:13 pm

Tagging along for what promises to be an interesting discussion.

I have an ETX125 as well, together with the basic controller + the GoTo. I do not have the focus motor however and not sure Mead still sells those. I spoke to Meade few weeks back and it's a pity they don't make it anymore (they also moved all their manufacturing to China).

In any event, the GoTo worked fine the few times I've tried it. However, to me one of the more challenging activities is telescope alignment, whether you're in Alt-Azim or REC-Dec modes. I was 'hoping' that by adding few sensors + a GPS, one can automate both the alignment part as well as the GoTo.

I also have all the cables/hardware and was able to control the motors with Palm IIIe (anyone remembers those?) with some sort of Planetarium software, running on a monochrome LCD screen.

The one thing 'slowing' me down is, the telescope is now ~15 years old and do not want to break/burn anything in it as most likely, no spare parts are available.

ozarchie
Posts: 1
Joined: Wed Nov 02, 2016 1:06 am

Re: Direct telescope control of Meade RA & Dec drives

Sun Nov 05, 2017 3:30 am

I did some work on this back in the early 2000s.

Attached is the last working doc - including errors.

A lot of info is on this site -:
http://www.astrogene1000.com/products/a ... _clone.htm

Cheers
Archie
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