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Celestron Nexstar "AUX" port... Serial to TTL

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#76 derelicte

derelicte

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Posted 24 October 2013 - 01:47 PM

Great work!

Is nextremote the only sw that can communicate with the mount over this interface? The reason I ask is I'd like to build a bluetooth serial adapter that plugs into the aux port and communicates with a tablet running Sky safari.

I have this setup working now, but the bluetooth adapter is plugged into the hand control. I'd like to move it to the aux port so I can power it from the mount and not use another battery.

This circuit is pretty simple. I could design a pcb pretty easily that should only cost a few dollars from my favorite cheap pcb house, oshpark.com

Thanks!

#77 ur7x

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Posted 24 October 2013 - 07:40 PM

As far as I have been able to determine, the scope needs either NexRemote or the HC (and not both at the same time) to store the scope alignment... No NexRemote or no HC and the scope is basically clueless as to where it is pointing.

All connections that I have seen that attempt to control the scope need to go through either NexRemote or the HC

There are bluetooth and wifi tools that will let an iPad perform a remote takeover of a PC (or a laptop) but this just add layers of complexity.

Have you tried running the Sky Safari through the virtual com port in NexRemote... That seems to be how it is done.

#78 derelicte

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Posted 25 October 2013 - 09:43 AM

That's a bummer. I was hoping to eliminate the bt connection to the hc.

I haven't tried connecting nexremote to the bt adapter because of a limitation in the nexremote software. It won't let you connect to a serial port above 16. The bt stack running on my laptop creates a virtual com port in the 40's. I haven't bothered to try a different bt adapter and stack to try this out as I don't want to use nextremote as a bridge. I just want the tablet to connect to the scope directly via bt.

So until sky safari can talk to the mount via the aux port, I guess my idea is dead. :(

#79 vicd

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Posted 10 December 2013 - 08:41 AM

First off, congratulations on seeing this undertaking through to the end! Based on this thread it was a wild and challenging ride!

I'm new here and this is my first post. I was hoping you could answer a question though.

I've got Parkinson's disease and the tremors that go along with it so I try to avoid (or at least minimize) soldering tasks. I'd like to try making this homebrew AUX-to-PC port adapter on one of those prototyping boards using sockets, pins, posts, and wire jumpers, etc. rather than soldering and then if/when I get it working I could drizzle it with epoxy to 'lock it down'.

With that in mind, I was wondering... based on what you know now would it be possible or advisable to try to leverage one of the prefab serial to TTL (or USB to TTL) interface modules found on eBay or are they not suitable for the application? Could the right prefab module (maybe one that already includes the 5 V regulator) be wired with the 74HC125 chip to streamline construction?

I saw that this was the root of your original question that kicked off this thread but I didn't see that this possibility got pursued or investigated. Is it worth exploring further?

I wonder why Celestron stopped making the auxiliary port accessory? It was definitely the easiest way to add a PC port to a Celestron mount. It's not like they wouldn't sell!

Thanks in advance for your time.
Vic

#80 ur7x

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Posted 10 December 2013 - 11:45 AM

First off, congratulations on seeing this undertaking through to the end! Based on this thread it was a wild and challenging ride!

I'm new here and this is my first post. I was hoping you could answer a question though.

I've got Parkinson's disease and the tremors that go along with it so I try to avoid (or at least minimize) soldering tasks. I'd like to try making this homebrew AUX-to-PC port adapter on one of those prototyping boards using sockets, pins, posts, and wire jumpers, etc. rather than soldering and then if/when I get it working I could drizzle it with epoxy to 'lock it down'.

With that in mind, I was wondering... based on what you know now would it be possible or advisable to try to leverage one of the prefab serial to TTL (or USB to TTL) interface modules found on eBay or are they not suitable for the application? Could the right prefab module (maybe one that already includes the 5 V regulator) be wired with the 74HC125 chip to streamline construction?

I saw that this was the root of your original question that kicked off this thread but I didn't see that this possibility got pursued or investigated. Is it worth exploring further?

I wonder why Celestron stopped making the auxiliary port accessory? It was definitely the easiest way to add a PC port to a Celestron mount. It's not like they wouldn't sell!

Thanks in advance for your time.
Vic


Thanks for the post, your idea of starting with a prefab serial to ttl board was exactly my idea, but after I got into the project, it became clear to me that the risk to my mount(s) was not worth the few bucks I was going to save so I abandoned that line of thought. To do this I would have to build a test/simulate/stimulate system to ensure that a confortable <5V ttl signal was all that was coming out of the translater. Of course the curiosity here was that I had to build that setup anyway before I was willing to chance a $1200 (or even a $600) mount on a home brew project. And as you will note, as you follow my thread here, it is EASY to make a simple mistake and build something that could (and likely would have) killed my mounts electronics.

I have some luxury in that where I work, I have a small army of guys who work for me who would love to take a break from configuring servers and network equipment and solder something goofy "for the boss".

Ask around,I'm sure you will find friends and family who will solder this up for you in exchange for a bottle of wine or a 6pack of beer.

Failing that, the OE converter still do come up for sale from time to time on the classifieds here or on ebay. They seem to go for about $50 (I got mine for $40), vendor claimed it was "new" It had clearly been out of the box, but it was mint and it works perfectly so who am I to complain.

And ya, given that the guts of these things probably cost Celestron around $1.50 (I bought enough components to build 2 for less than $8...) I can not see why the new mounts don't come with PC ports built in or even better why they don't still sell these converters.

Once you have controlled your mount with a PC app like TheSky (or what have you), you will never got back to the hand controller. For those of us with a semi-permanent pier set up, or a permanent observatory, this is the first thing to buy/build/obtain.






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