Maurizio Baldassarre replied to the topic 'DIY focuser w/o Motor HAT or PiFace?' in the forum. 2 years ago

Any tips on what would be the best way to determine the number of backlash steps?

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Maurizio Baldassarre replied to the topic 'DIY focuser w/o Motor HAT or PiFace?' in the forum. 2 years ago

Is there a way to have INDI calculate the necessary number of steps for backlash compensation? Or should I determine it by hand?

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Maurizio Baldassarre replied to the topic 'DIY focuser w/o Motor HAT or PiFace?' in the forum. 2 years ago

I DID IT!!!! I took the risk and increased the voltage to 12 V, and not it works! I have no idea why it says 3.45V on Amazon, must be a typo!!

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Maurizio Baldassarre replied to the topic 'DIY focuser w/o Motor HAT or PiFace?' in the forum. 2 years ago

On the Amazon page it says "nominal voltage: 3.45 V, nominal current: 1.5A (monophase)".

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Maurizio Baldassarre replied to the topic 'DIY focuser w/o Motor HAT or PiFace?' in the forum. 2 years ago

It's not a 28BYJ-48 (unipolar), but a Nema 17 (bipolar). I don't think the a4988 can drive unipolar motors, so I purchased this one for testing. The motor does not vibrate nor gets warm. Looks like no current is flowing at all. Maybe Vref is too low. The voltage on the motor pins on the driver board rises to 4.6 V while I'm sending commands. Starting to think it's a matter of current.

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Maurizio Baldassarre replied to the topic 'DIY focuser w/o Motor HAT or PiFace?' in the forum. 2 years ago

Thank you very much Radek,

I have wired everything and checked all connections with a multimeter. The motor just won't work. I'm starting to think it must be some sort of software issue, for instance missing libraries.
I attached pictures of the RPi and board, and screenshots of the "Astroberry Focuser" tab under INDI. Please not that the default port is /dev/ttyUSB0. This is weird, why should it be USB?

When I send move commands via Ekos, the voltage on SLEEP rises to 3.3, so I think the RPi does send commands. I checked the voltage of the motor at rest, and the readout is 1.5 volts on each of the 4 pins relative to motor power supply GND. Strange.

Vref does not go beyond 1.2V. Is that enough?

Any explanation?

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Maurizio Baldassarre replied to the topic 'DIY focuser w/o Motor HAT or PiFace?' in the forum. 2 years ago

I finally got to load the indi_rpifocus driver, I had to recompile them source. I get the Astroberry Focuser tab in my Ekos client. I still DO NOT manage to get the motor going. Could anyone who has managed to get the a4988 board working tell me which pins of the a4988 board should be connected to? Including power lines, I mean.
Thanks!

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Maurizio Baldassarre replied to the topic 'DIY focuser w/o Motor HAT or PiFace?' in the forum. 2 years ago

I have double checked all connections and they're alright. This is what I get when I load indi_rpifocus in indiserver:

2017-09-05T17:29:58: Driver indi_gphoto_ccd: pid=2008 rfd=3 wfd=6 efd=7
2017-09-05T17:29:58: Driver indi_asi_ccd: pid=2009 rfd=4 wfd=9 efd=10
2017-09-05T17:29:58: Driver indi_lx200autostar: pid=2010 rfd=5 wfd=12 efd=13
2017-09-05T17:29:58: Driver indi_rpifocus: pid=2011 rfd=8 wfd=15 efd=16
2017-09-05T17:29:58: listening to port 7624 on fd 11

What could the problem be? Could it be that my Ekos client (running on my Mac) does not recognize the driver? I am still puzzled by the SLEEP-RESET connection dilemma.

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Maurizio Baldassarre replied to the topic 'DIY focuser w/o Motor HAT or PiFace?' in the forum. 2 years ago

I am going to double check all connections with a multimeter then. One thing that is not clear to me is if I should connect the RESET pin with the SLEEP pin, which is in turn connected to GPIO23 on the RPi3. It does not say anything on the Readme file ( https://github.com/rkaczorek/astroberry-diy/blob/master/README ), but it is usually connected as shown in many other images on Google (see here ).

Regarding Vref, it should be measured between the GDN pin powering the board and the top of the potentiometer, right? The Nema 17 has a nominal current limit of 1.5 A monophase (does it mean "per coil"?). What value should Vref be set to? 3 V?

Do I need to power the motor via Vmot (nominal tension 3.45 V) or is the board powering it via Vdd?

Sorry for all these questions, which you might find stupid or obvious, but this is the first time I deal with stepper motors.

Maurizio

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Maurizio Baldassarre replied to the topic 'DIY focuser w/o Motor HAT or PiFace?' in the forum. 2 years ago

I've been busy trying to get myself a PiFace Digital 2 but no luck, these little things seem to disappear faster than they are supplied. Should definitely get one asap. In the meantime I have received a Nema17 motor and a4988 driver board. I have tried to connect the board to the RPi3 as per instructions in INDI Astroberry website, but no luck. When I load the indi_rpifocus driver in indiserver, no Astroberry Focuser tab will show up in Ekos. I have installed INDI Astroberry from the .deb file at https://sourceforge.net/projects/astroberry/ . Any idea why it's not working?

Maurizio

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Maurizio Baldassarre replied to the topic 'DIY focuser w/o Motor HAT or PiFace?' in the forum. 2 years ago

Dear Helge,
if I understand correctly, I must load the astroberry-piface driver, right? Can you confirm that it supports the PiFace Digital 2? My RPi3 runs on Ubuntu Mate, but as I read here ( http://indilib.org/forum/general/699-astroberry-initial-release.html?start=24 ) it may not work on Ubuntu Mate.

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Maurizio Baldassarre replied to the topic 'DIY focuser w/o Motor HAT or PiFace?' in the forum. 2 years ago

Hi Helge, thanks a lot!
So I need to get myself PiFace Digital 2, right? Can it handle two motors in parallel (I plan to have for the guider scope, too)?

Maurizio

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Maurizio Baldassarre created a new topic ' DIY focuser w/o Motor HAT or PiFace?' in the forum. 2 years ago

Hi folks,

I have just bought a bunch of 28BYJ-48 stepper motors and each came with its own ULN2003 driver board ( Amazon link here ). I can control the motors with Python by connecting the driver board pins to some GPIO pins on my RPi. My question is: do I need some kind of hardware interface between the RPi and the motors (such as Adafruit motor HAT or PiFace digital) even if I already have the driver boards? Will I be able to perform automatic focusing within Ekos using e.g. Astroberry Focuser simply by connecting the driver boards to the GPIO pins?
Thanks!

Maurizio

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