Arduino Ascom focuser Mark2

[blackdragon72]

There is a 4k7 pullup on my circuit diagram on SF http://sourceforge.net/p/arduinoascomfocuser/wiki/Schematic/attachment/AAF2_V2.2_crop.png. The schematic in the wiki section is the latest version.

I was referring to MOSFET in the first digram (Figure 4). I am not sure if it is needed in our design, from datasheet it seems that it might be required. Since UNO has extra 5V connector pin, I just use Figure 5.

[blackdragon72]

No its not supported in the driver.

To support this feature, does the driver need to read temperature periodically and adjust focus accordingly?

[Gina]

I don't understand the MOSFET in Figure 4.  I use a digital pin on the Arduino connected to the DQ line with parasitic power.  No MOSFET.  I use this arrangement on my weather station to save wires going up the mast.  One twisted pair is all that's required

[tekkydave]

I don't understand the MOSFET in Figure 4.  I use a digital pin on the Arduino connected to the DQ line with parasitic power.  No MOSFET.  I use this arrangement on my weather station to save wires going up the mast.  One twisted pair is all that's required

I've never seen a discrete MOSFET used like that on the 1-wire data line. Maybe it is denoting an active pullup for a large number of devices or long runs but the 4k7 resistor is fine for a few devices. My weather station uses a usb 1-wire interface (DS9490R) which contains an active pullup internally.

[tekkydave]

To support this feature, does the driver need to read temperature periodically and adjust focus accordingly?

I'm not sure how temperature compensation works - whether it is a function of the driver or client application. It would be easy to change the driver to return true but that may not be enough to make it work.

[tekkydave]

There is a 4k7 pullup on my circuit diagram on SF http://sourceforge.net/p/arduinoascomfocuser/wiki/Schematic/attachment/AAF2_V2.2_crop.png. The schematic in the wiki section is the latest version.

I have also uploaded the v2.2 schematic to the Files/Drawings section on SF as there was only the original drawing without the temperature sensor.

[redtail]

http://www.jangeox.be/2013/10/change-unipolar-28byj-48-to-bipolar.html. Found this---- interesting.

[Gina]

http://www.jangeox.be/2013/10/change-unipolar-28byj-48-to-bipolar.html. Found this---- interesting.

WOW!  That's brilliant - thank you for posting the link   I use lots of these stepper motors   In bipolar mode I would imagine a 5v motor could be used on 10v.  Or a 12v motor on 24v.

[redtail]

Looks like the code has to be altered to use this Gina and thats a bit above me i am  afraid. 

[Gina]

Looks like the code has to be altered to use this Gina and thats a bit above me i am  afraid. 

Just copy someone else's

[redtail]

Just copy someone else's

But will it still work with the .AAF2.Focuser ?

[tekkydave]

But will it still work with the .AAF2.Focuser ?

Have a go. You will only need to change the nano sketch. I'm ok with the motor I'm using so I don't plan to make any other changes at the moment.

[Gina]

I have had no problem with the standard 28BYJ-48 as supplied lacking power for all the focusers I have used so far - they're quite powerful little beasties   Even half-stepping.  But if I do come across an application needing more power I'll know what to do

[redtail]

I bought a 12 volt stepper to replace the 5 volt and it is much better.

http://cpc.farnell.com/jsp/search/browse.jsp?N=213718&ref=lookahead

CLIFF ELECTRONIC COMPONENTS - FMJ7301CH - MOTOR, STEPPER, 12V, 64:1

[wuthton]

I bought a 12 volt stepper to replace the 5 volt and it is much better.

http://cpc.farnell.com/jsp/search/browse.jsp?N=213718&ref=lookahead

CLIFF ELECTRONIC COMPONENTS - FMJ7301CH - MOTOR, STEPPER, 12V, 64:1

Out of interest, what was wrong with the 5 volt?

I've got an Atik, an 8 position filter wheel and a flattener hung off my focuser and it all moves perfectly and with very fine steps. It's even attached to the coarse focus knob on a ####### #### William Optics crayford (I keep giving the Moonlites lusty glances!).

Edited November 22, 2014 by wuthton

[redtail]

Out of interest, what was wrong with the 5 volt?

I've got an Atik, an 8 position filter wheel and a flattener hung off my focuser and it all moves perfectly and with very fine steps. It's even attached to the coarse focus knob on a ####### #### William Optics crayford (I keep giving the Moonlites lusty glances!).

Would start to move the focuser on my rc8 but would give up Two atiks , oag ,reducer,filter wheel.

[wuthton]

Would start to move the focuser on my rc8 but would give up Two atiks , oag ,reducer,filter wheel.

Ahh... GotYa.

[tekkydave]

Thats mainly why I used a 9V battery to power the nano and stepper. I may switch to 12V in the future - the controller board will take 5 to 12V according to the spec.

[Gina]

I'm using the 12v version of the 28BYJ-48 running off the 13.8v supply.

[redtail]

Hi

Can some one help me with pins on the uno.

I have a stepper i wish to use on another scope and the colours are different to the small geared one.

The colours are /A = Yellow  A = Orange

/B = Black   B = Brown and red and blue - and +

Which pins would match the code as above.

Thanks

Kenny

[SnakeyJ]

Dave - many thanks for providing the ascom driver and this great resource and tutorial.     After finally borrowing a replacement soldering iron, I finally completed this last night and now have it working via Ascom with Firecapture.     I still need to do another revision of the mount to fit my OO OC1 focuser and will probably upgrade to the 12V version of the 28BYJ48 to cope with the weight of the imaging train.

I'll need to find a 4K7 resistor to complete the 1wire temp enhancement, but otherwise ready to roll when the clouds part

[redtail]

Dave - many thanks for providing the ascom driver and this great resource and tutorial.     After finally borrowing a replacement soldering iron, I finally completed this last night and now have it working via Ascom with Firecapture.     I still need to do another revision of the mount to fit my OO OC1 focuser and will probably upgrade to the 12V version of the 28BYJ48 to cope with the weight of the imaging train.

I'll need to find a 4K7 resistor to complete the 1wire temp enhancement, but otherwise ready to roll when the clouds part

I used one of these they work fine--- http://www.ebay.co.uk/itm/121024657930?_trksid=p2060778.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

[tekkydave]

Dave - many thanks for providing the ascom driver and this great resource and tutorial.     After finally borrowing a replacement soldering iron, I finally completed this last night and now have it working via Ascom with Firecapture.     I still need to do another revision of the mount to fit my OO OC1 focuser and will probably upgrade to the 12V version of the 28BYJ48 to cope with the weight of the imaging train.

I'll need to find a 4K7 resistor to complete the 1wire temp enhancement, but otherwise ready to roll when the clouds part

Great news - well done. Glad you can make use of it.

[Gina]

I was kinda wondering if the ASCOM focuser could be extended to work with more than one scope at a time but I think this is probably asking too much

[SnakeyJ]

I was kinda wondering if the ASCOM focuser could be extended to work with more than one scope at a time but I think this is probably asking too much

They would all have different comm ports so should be okay. Though 3 cheap laptops might be a whole lot simpler and more stable [emoji3]