i have a crayford 2" hand focuser witch 1:8 reduction gear (standard skywatcher's focuser) I'd like to remote control.
My first idea was to use a moonlight packaged autofocuser but... it costs 3x my setup (about 800 euros in italy). So I was thinking about using someone else's diy focuser which uses a common driver already working on indilib.
It doesn't answer your question directly but I'm building auto focuser too. Here are some pictures.
Motor is Nema11 sized stepper with MXL 15T pulley and belt attached to micro focusing wheel (in case of TS apo it gives reduction 1:10 or 11). Belt teeth don't exactly fit into the focuser wheel but it's working even when the belt is quite loose. Aluminium bracket is 2mm thick, screws are M2.5. Belt length is MXL60 and width 6mm. It's controlled by stepper motor driver and arduino nano hidden in the white box with blue buttons on the first picture, 2 buttons are for slow F/B, two other for fast forward/backward (original idea was to use two for driving F/B and other two as speed regulation, it's just sketch issue). Inside the box now is Pololu DRV8834 but I plan to upgrade it eventually with Silent Step Stick (I have them in EQ5 handcontroller and I'm very pleased with silent, smooth and precise operation). Actually I don't use this focusing box at all, I reconnect cable from DEC motor and operate the focuser with mount handcontroller when RA motor is still tracking - don't need DEC for focusing.
So far it's for manual remote focusing, better than touching the focuser with fingers but not automatic. That will be next step but I didn't get into Indiduino and Formata protocol yet. Arduino is loaded with Formata sketch and appropriate INDI driver is modified with correct arduino pins, then PC (RPi3 in my case) is connected to Arduino via USB and it should work.
I looked briefly into formata/indiduino files but I didn't understand it very much where and how to define step/dir/sleep pins in indiduino (also my sleep pin is common with reset and microstepping DRV pins but I have separated Enable).
Looks promising, understandable code with possible modifications. The only thing is that it's so complex that last hour I've been just installing missing libraries and for some reason can't get LCD.h working. "No such file or directory". Despite LCD.h is present in LiquidCrystal library. Or did I missed something? Is there a simple "focuser only" sketch? I don't need LCDs, sensors, analog buttons...
at the end of .pdf file is addressed uneven microsteping issue with DRV8825 and possible solution with four diodes. Didn't give satisfactory results. DRV8834 shows smoother movement but keeps missing steps on regular basis (different microsteping with only 2 MS pins and limited motor voltage to under 11V and max current is 1.5A). Absolutely smooth and even microsteping can do only Silent Step Stick (look at github, easiest to order from Germany or your local distributor, don't bother to search on eBay). There is a user friendly version for 5V systems only, I recommend to start with that one so no need to worry about power up sequence. And as a bonus it's really absolutely silent (in silent mode, I didn't notice any noticeable drop in torque). At slower speeds I have to look or touch the belt to sense a motion, so silent it is.
edit: I overlooked description of various versions. Simple "focuser only" is under file DRV8825_M (-> Focuserv168_DRV8825_M.ino). Now it compiles fine.
uses INDIDUINO - I didn't find it very user friendly.
I just mock tested Focuserv168_DRV8825_M.ino and it indeed works with moonlite driver under INDI. I have to make some changes for my construction as it rotates the motor too slowly (I'm using 1/32 microstep but driver is made for full or 1/2 step). It's the way to go.
Easydriver is fine.
+ you don't need any other components (like capacitors) as one is already on the driver (all other common drivers such as DRV8825, DRV8834, SSS etc must have capacitor between Vin and GND, size about 47-100uF and not less than 50V to eliminate voltage spikes, believe me, driver won't survive that).
- easy driver can drive motor with only 500mA and it tend to generate some heat. My Nema11 motors are 670mA and Nema 14 motors on eBay run on 800mA or 1200mA. Running these motors with easydriver gives probably too little torque.
- offers only 1/8 microsteping but not sure how much limiting this is. My EQ5 handcontroller is using Silent Step Sticks (SSS) at 1/32 microsteps and the highest slew speed is 1000x sidereal so fainter steps don't limit max speed.
The only photos I have right now are here Invalid consumer key/secret in configuration Invalid consumer key/secret in configuration
I dont know what a beagleboard is. I used an arduino, an arduino ethernet module and and arduino stepper module. These 3 sit inside a small project box. The motor is connected with a cable to this box.
Hi and thanks to all.
At the moment I' working on the sourceforge's hosted one (there are 2 version in two different repositories from the same author). I'm having some difficulties using his code, it makes my steppers (a nema 17 and a nema 17 PG27 reduction gear) move in a strange way - they move perfectly using some simple code).
I managed to attach the nema 17-PG27 to the focuser in a pretty stable way and now i'm using this guy code and try to find a way do make it usable on my steppers. I preferred the v168 as the Moonlite compatibility layer is fully functional on indi's moonlite driver. As I intend to use it as a "remote hand" for my focuser, i'm implementing the simplest schema (stepper, arduino nano, DRV8825 from pololu and a probe - is it used ?).
I use the same - the Arduino ASCOM Focuser Pro DIY, version 1 (the one working with INDI). THere has been som issues with the code, and Robert actually adviced me to use an older version of the Arduino software to compile the code. Ask him directly (via the forum or direct email) - he's very keen on assisting, in my experience!
I'm actually building my second of the same model right now, to a second scope.
Celestron C11, Skywatcher 100 ED Pro
Atik 383L+, ASI294