Hi, I'm a litlle confused here. In the previous incarnation, in the supporting document myFocuser_Moonlite_v101.pdf, there is the Q/A:
Can I use a MoonliteTM focuser motor with the myFocuser controller.
YES.
Only a small modification is required. Pins 1-4 are compatible with a MoonliteTM focuser motor.
Pin5 of the RS232 connector needs to be connected to 12V DC supply rail and GND connected to the metal part of the RS232 connector. Thus two extra wires must be soldered inside the myFocuser case (12V and GND).
And in this case, the controller appears to be the DRV8825, with no mention of Unipolar or Bipolar. So is this not accurate, or can you use the DRV8825 with the additional wires. And if not, would it be possible to use the ULN2003 and Nano to drive this motor.
Thanks,
Mark
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Hi Mark
The document you refer to is indeed on the prior v1 site. The document however, does not make mention of driver type such as DRV8825. What it does say is we need to provide 12V to the stepper wire via the RS232 connector. This would mean connecting the 12V supply rail that powers the driver chip to pin5 of the rs232 connector.
According to the Moonlite document, part of which is attached here, there are 4 wires allocated for the stepper plus the 12V and that they use a unipolar hurst motor (so I assume the 12V must be the center tap). That would mean powering it via a ULN2003 or L293D Motor Shield as they support Bipolar motors. I would assume the better choice to be the L293D shield which can provide more current.
The full document can be found searching google for MoonLite High Resolution Stepper Motor Options
It is clear that they use a Hurst Unipolar stepper motor. So using it with a DRV8825/RAPS128 etc is out of the question. Apologies if this was not clear.
Hi Robert, Thanks for the quick response. I've kind of committed to a Nano design. Any reason not to use the "Mini-Motor-Drive-Shield-Expansion-Board-L293D-Module-For-Arduino-UNO-MEGA2560-R3" as found on ebay, but wire it into a Nano HW203-ish design in place of the DRV8825?
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Hi Mark
Ive just looked at the module on ebay. I will admit I was unaware of this mini module. Looking at it, it only has 4 output pins to the motor (A+-, B+-), so looks like it only supports bipolar motors. I see no way in which to tap a center-wire in to support unipolar steppers.
Some sites suggest wiring this 12V line from the moonlite motor (pin5) to the 12V extn battery supplying the L293D external power, but I have not tried this do not know if this will work. I do not have a moonlite motor at present to test this.
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So my understanding is, in a bipolar stepper, each pair of outputs work together, one sources and one sinks current through the connected coil in the motor. In a unipolar stepper, the coils are tapped in the center and the output connections of the driver board will sink current only, based on which output is set low. This agrees with what I've found on the net for driving unipolars with the l293d, the +12v would be connected to the 5th, Vcc wire, and current would flow through whichever half coil is enabled with a low.
The driving sequence would be identical to the bipolar case.
Do you agree with this interpretation?
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Hi Mark
Ive ordered a board to test - i can use a 28BYJ-48 unipolar stepper I have to test it with. So I wacked together some code, schematics and layout to test with the hardware - they are zipped here but of course untested as I do not have the hardware yet. I'm hopeful it will go.
Cheers
Robert
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Thanks for your support. I still have some work to do, putting my project in a box, mounting buttons and connectors, testing, in addition to acquiring the driver board. Hopefully you'll get a chance to test it before I'm done. Thanks for the schematics, code, etc. I thought I was going to have to do that myself.
--Mark
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Hi Robert,
My L293D mini board finally came, and I purchased an Adafruit unipolar 12V stepper motor and connected it all up an it seems to work! I need to get a larger project box because my current one will not fit the mini board. My next step will be to test my moonlite focuser with it, but I'm feeling pretty good about it working. One minor note on the circuit is that the VCC connection is not necessary if 12V is connected to VIN, in fact, it should only be used if VCC=VIN and you jump them together on the board. Otherwise, VCC goes nowhere. Thanks for the test circuil/code. I'll let you know when I get it all going.
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Hi Mark
I am still waiting for mine, so appreciate the update!
I believe I had 12V going to VCC of the L293D board.
Then I put the 12V into an LM808 board the output of which drove VIN on the Nano?
12V going direct to VIN on the nano will blowup most chinese clones.
It will be clearer when you receive your board. The VIN connection (+12V) goes to a local regulator on the L293D mini board and drives VCC. The VCC input on the board can only reach the IC if you add a 0 ohm resistor or jumper wire on the board which connects VCC to VIN directly. You would only do this if you were driving a 5V stepper where the voltages are the same. Not the case here though, and as I said, the VCC pin doesn't go anywhere without the jumper. I just checked the board and in this configuration (no VCC) I get a nice 4.95V on pin 16 of the L293D IC.
Thanks for the updates.
--Mark
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Hi Mark
Appreciate the update, it is nice to be told what to look for instead of trying to troubleshoot in the dark, so very much appreciate the heads up.
Cheers
Robert
Last edit: brownrb 2017-02-11
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Happy to say, I connected up my Moonlite CSL focuser and it is working. I connected the 5 wires as indicated in the Moonlite diagram and connected ground to the shield and the stepper was moving smoothly in both directions. I just have to repackage things into a larger project box, but I think it looks good. You may want to test a bit more extensively, but as far as I can tell, driving unipolar steppers with the L293D mini appears to work. Thanks for your support and help
--Mark
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Hi,
I have reach the limits of my stock focuser, so I'm looking to upgrade to a Moonlite for my Newt.
(since i Purchased a QHY168c)
I am running a DRV8825_HW203_F now
i see this thread is from Feb. Is this working good ?
is it Suported with Myfocuser2 software/drivers Ascom.
i think i have enough spares to build L293d version. if it will control th Hi Res Moonlite Motor.
thanks
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Yes, my Moonlite CSL with the Hi Res stepper has been working flawlessly. It is fully supported by the Myfocuser 2 SW and the Ascom drivers. Highly recommended.
--Mark
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hi
im looking at building the myfocuser2 with the uno and l293d shield
to drive a moonlite hi res stepper
im assuming based on the result above, this will work?
any low backlash geared stepper recommendations that are similar to the hurst used in the moonlites?
objectivr is to use one controller for two scopes, one with a moonlitr motor and onr with a generic stepper
itll be one scope at any time of course
thanks
alistair
Edit : will the "Adafruit Motor/Stepper/Servo Shield for Arduino v2 Kit - v2.3" which is compatible with the uno work with the code for myfocuser2 and a moonlite stepper?
Hi, I'm a litlle confused here. In the previous incarnation, in the supporting document myFocuser_Moonlite_v101.pdf, there is the Q/A:
Can I use a MoonliteTM focuser motor with the myFocuser controller.
YES.
Only a small modification is required. Pins 1-4 are compatible with a MoonliteTM focuser motor.
Pin5 of the RS232 connector needs to be connected to 12V DC supply rail and GND connected to the metal part of the RS232 connector. Thus two extra wires must be soldered inside the myFocuser case (12V and GND).
And in this case, the controller appears to be the DRV8825, with no mention of Unipolar or Bipolar. So is this not accurate, or can you use the DRV8825 with the additional wires. And if not, would it be possible to use the ULN2003 and Nano to drive this motor.
Thanks,
Mark
Hi Mark
The document you refer to is indeed on the prior v1 site. The document however, does not make mention of driver type such as DRV8825. What it does say is we need to provide 12V to the stepper wire via the RS232 connector. This would mean connecting the 12V supply rail that powers the driver chip to pin5 of the rs232 connector.
According to the Moonlite document, part of which is attached here, there are 4 wires allocated for the stepper plus the 12V and that they use a unipolar hurst motor (so I assume the 12V must be the center tap). That would mean powering it via a ULN2003 or L293D Motor Shield as they support Bipolar motors. I would assume the better choice to be the L293D shield which can provide more current.
The full document can be found searching google for MoonLite High Resolution Stepper Motor Options
It is clear that they use a Hurst Unipolar stepper motor. So using it with a DRV8825/RAPS128 etc is out of the question. Apologies if this was not clear.
Regards
Robert
Hi Robert, Thanks for the quick response. I've kind of committed to a Nano design. Any reason not to use the "Mini-Motor-Drive-Shield-Expansion-Board-L293D-Module-For-Arduino-UNO-MEGA2560-R3" as found on ebay, but wire it into a Nano HW203-ish design in place of the DRV8825?
Hi Mark
Ive just looked at the module on ebay. I will admit I was unaware of this mini module. Looking at it, it only has 4 output pins to the motor (A+-, B+-), so looks like it only supports bipolar motors. I see no way in which to tap a center-wire in to support unipolar steppers.
Some sites suggest wiring this 12V line from the moonlite motor (pin5) to the 12V extn battery supplying the L293D external power, but I have not tried this do not know if this will work. I do not have a moonlite motor at present to test this.
So my understanding is, in a bipolar stepper, each pair of outputs work together, one sources and one sinks current through the connected coil in the motor. In a unipolar stepper, the coils are tapped in the center and the output connections of the driver board will sink current only, based on which output is set low. This agrees with what I've found on the net for driving unipolars with the l293d, the +12v would be connected to the 5th, Vcc wire, and current would flow through whichever half coil is enabled with a low.
The driving sequence would be identical to the bipolar case.
Do you agree with this interpretation?
Yes, I have read that also. The proof is in the test
Last edit: brownrb 2017-01-27
Hi Mark
Ive ordered a board to test - i can use a 28BYJ-48 unipolar stepper I have to test it with. So I wacked together some code, schematics and layout to test with the hardware - they are zipped here but of course untested as I do not have the hardware yet. I'm hopeful it will go.
Cheers
Robert
Thanks for your support. I still have some work to do, putting my project in a box, mounting buttons and connectors, testing, in addition to acquiring the driver board. Hopefully you'll get a chance to test it before I'm done. Thanks for the schematics, code, etc. I thought I was going to have to do that myself.
--Mark
Hi Robert,
My L293D mini board finally came, and I purchased an Adafruit unipolar 12V stepper motor and connected it all up an it seems to work! I need to get a larger project box because my current one will not fit the mini board. My next step will be to test my moonlite focuser with it, but I'm feeling pretty good about it working. One minor note on the circuit is that the VCC connection is not necessary if 12V is connected to VIN, in fact, it should only be used if VCC=VIN and you jump them together on the board. Otherwise, VCC goes nowhere. Thanks for the test circuil/code. I'll let you know when I get it all going.
Hi Mark
I am still waiting for mine, so appreciate the update!
I believe I had 12V going to VCC of the L293D board.
Then I put the 12V into an LM808 board the output of which drove VIN on the Nano?
12V going direct to VIN on the nano will blowup most chinese clones.
I will upload the code and schematics I have now
https://sourceforge.net/projects/arduinoascomfocuserpro2diy/files/DRIVER%20BOARDS/BOARD%20L293D%20MINI%20PLUS%20NANO/
The firmware in usual place
https://sourceforge.net/projects/arduinoascomfocuserpro2diy/files/CODE%20ARDUINO/
The pdf found here
https://sourceforge.net/projects/arduinoascomfocuserpro2diy/files/DRIVER%20BOARDS/
Cheers
Robert
It will be clearer when you receive your board. The VIN connection (+12V) goes to a local regulator on the L293D mini board and drives VCC. The VCC input on the board can only reach the IC if you add a 0 ohm resistor or jumper wire on the board which connects VCC to VIN directly. You would only do this if you were driving a 5V stepper where the voltages are the same. Not the case here though, and as I said, the VCC pin doesn't go anywhere without the jumper. I just checked the board and in this configuration (no VCC) I get a nice 4.95V on pin 16 of the L293D IC.
Thanks for the updates.
--Mark
Hi Mark
Appreciate the update, it is nice to be told what to look for instead of trying to troubleshoot in the dark, so very much appreciate the heads up.
Cheers
Robert
Last edit: brownrb 2017-02-11
Happy to say, I connected up my Moonlite CSL focuser and it is working. I connected the 5 wires as indicated in the Moonlite diagram and connected ground to the shield and the stepper was moving smoothly in both directions. I just have to repackage things into a larger project box, but I think it looks good. You may want to test a bit more extensively, but as far as I can tell, driving unipolar steppers with the L293D mini appears to work. Thanks for your support and help
--Mark
Hi,
I have reach the limits of my stock focuser, so I'm looking to upgrade to a Moonlite for my Newt.
(since i Purchased a QHY168c)
I am running a DRV8825_HW203_F now
i see this thread is from Feb. Is this working good ?
is it Suported with Myfocuser2 software/drivers Ascom.
i think i have enough spares to build L293d version. if it will control th Hi Res Moonlite Motor.
thanks
Yes, my Moonlite CSL with the Hi Res stepper has been working flawlessly. It is fully supported by the Myfocuser 2 SW and the Ascom drivers. Highly recommended.
--Mark
Great news that saves my wife over $400.00
hi
im looking at building the myfocuser2 with the uno and l293d shield
to drive a moonlite hi res stepper
im assuming based on the result above, this will work?
any low backlash geared stepper recommendations that are similar to the hurst used in the moonlites?
objectivr is to use one controller for two scopes, one with a moonlitr motor and onr with a generic stepper
itll be one scope at any time of course
thanks
alistair
Edit : will the "Adafruit Motor/Stepper/Servo Shield for Arduino v2 Kit - v2.3" which is compatible with the uno work with the code for myfocuser2 and a moonlite stepper?
https://www.adafruit.com/product/1438
Last edit: Alistair samson 2017-11-15