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[pterodyne]

Previously I had been working on a Losmandy Titan conversion.  This project never finished because my original motors (nema 17) were too weak.  And after all the mount is "working" as is with the gemini II controller and it is my live mount and installed 100 miles away in the observatory.

Anyway, recently I made a trade for the mount in the attached pictures.  It has a 15" 359 tooth worm wheel on RA and a 9.7 221 tooth worm wheel on the DEC.

Im working on using my previously purchased NEMA 23 motors.

https://www.pololu.com/product/1478
They are 2.8A per phase @ 3.2V nema 23 @ 270 Oz-In

These will have to be current limited, and the torque will suffer as noted by Tom in the Losmandy Titan conversion thread.

So Tom, my question is as follows.  Im going to mechanically get the NEMA 23 motors working for fit and gear mesh etc. then I have two options (three really)

1. Use those current limited motors and hope they perform.
2. Get these motors:  https://www.pololu.com/product/1472   (Also NEMA 23 but 1A coils at a higher voltage rating of 7.4)  They are also rated at 125 OZ-in. instead of the 270 on the above. 

Tom, based on your experience do you think the 1A 7.4V motor will perform better as it is in spec of the drivers? Or do you think the current limited 2.8A 3.2V motor will work better?

3.  The last option is what I was really planning until I saw the 1A motor.  Get whatever spec NEMA 23 motor I need, and they are available way more powerful than either of the above, and use external DIR/STEP drivers but still use the Astro EQ to drive them.

Thanks!

[pterodyne]

I just found these:

https://shop.germanreprap.com/en/powerlolu-stepper-motor-driverup-10a

Called the powerlolu and can drive up to 10A.  Interesting, although, with the step modes not being software selectable and limit of 1/16 uStep, Im not sure why I wouldn't just go with the tons of cheap drivers available on ebay.  Just thought it might be interesting to someone here.

[pterodyne]

Ok, I bought one of these:

http://www.amazon.com/gp/product/B00DFSF9GE?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

I was having trouble getting the torque I needed at max amps on the 8825.

Tom, can you give me some pointers on how I should wire this in?

It has:

PUL+(+5V)
PUL-(PUL)
DIR+(+5 V)
DIR-(DIR)
ENA+(+5V)
ENA-(ENA)

The current and stepping modes are set via DIP switches

Then it has separate DC input for motor power and output for stepper.

Id think:

Step (second from bottom left pin) to PUL +
Dir (bottom left pin) to Dir +
ENABLE (top left pin) to ENA+
Tie the ENA- DIR- and PUL- to ground

Lets say im using 32 microstepping Id set the ST-M5045 to 32 and set the current for my motor.  Then the programming would be the same in the AstroEQ (leave the astroEQ as it is currently programmed

1.8 stepper
359 Worm gear
2 Motor gear

for RA.

Haven't even gotten the worm blocks/stepper mounted on DEC yet so I haven't really done much with it.

Thanks!

[pterodyne]

I've found at least one image showing pullup resistors between this driver and the controller.  But in that case it is a Mach3 CNC controller.

See attached.

[TCWORLD]

The connections you have said seem fine. You shouldn't need the resistors.

However one thing to note, because you don't have control over the mode select pins, there is an issue when a Go-To movement is performed (or high-speed slew from EQMOD >200x). Basically with 1/32 mode, the AstroEQ firmware will jump to 1/4 mode for high speed movements for better torque. Clearly your driver will stay in 1/32 mode so it will move 1/8th of the distance it should do.

There is a quick and dirty fix for this which is to set your driver into 1/32 mode. Then in the config utility select 1/4 mode (bear with me) and divide the motor angle by 8. So for a 1.8 degree motor, enter 0.225 degress into the config utility. This will result in exactly the same resolution, but the AstroEQ firmware will stay in 1/4 mode for all speeds.

You could also try 1/64 mode if you want. For that you would select 1/4 mode in AstroEQ and enter the motor angle divided by 16 (e.g. 0.1125 for a 1.8 degree motor).

[pterodyne]

Thanks for the reply.  I don't know what happened.  I was able to slew just fine, although sidereal seems unsmooth.

I was attempting to change the firmware to do 64 microstepping as your example showed.  Now though, when I first load the utility and connect, it says firmware corrupted or blank.  It goes through a repair, and then allows me to configure.  It even seems to write the firmware and load eqmod.  It just doesn't control the mount.  Then if I reconnect to the firmware utility, it says it's corrupt again. 

[TCWORLD]

Interesting.

Would you be able to upload the following .hex file to the AstroEQ, then connect with a serial terminal like PuTTY @ 9600 baud. It will print out the configuration stored in the EEPROM.

For uploading, there is a copy of avrdude.exe and avrdude.conf that comes with the AstroEQ config utility. If you copy both the .exe and .conf and the attached .hex file into the same folder (somewhere with no spaces in the file path!), then change the that folder in CMD. You can then upload by running the command (replace # with the com port number):

Code: [Select]

avrdude.exe -C"avrdude.conf" -patmega162 -carduino -b57600 -D -P\\.\COM# -Uflash:w:AstroEQEEPROMChecker.hex:i
If you could let me know what that prints out.

[pterodyne]

Im not sure what happened, but I went to do your instructions, and opened the utility instead.  It worked like it should . Then I was able to power it off, and reconnect and it seems to be storing the settings.

Do you still want me to try the instructions?

[TCWORLD]

If it's working now, no need. If it stops working again later on then you can try.